PREVALENCE AND INCIDENCE OF TUBERCULOUS INFECTION AND DISEASE IN INDIA:
Item
- Title
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PREVALENCE AND INCIDENCE
OF TUBERCULOUS INFECTION
AND DISEASE IN INDIA: - extracted text
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PREVALENCE AND INCIDENCE
OF TUBERUCULOUS INFECTION
AND DISEASE IN INDIA:
A Comprehensive Review
By:
A.K. CHAKRABORTY
PROJECT ON WHO-OPERATIONAE
RESEARCH IN TUBERCULOSIS
APW.
ALLOTMENT NO.SE/ICP/ J
£
TUB/001/VT.96.999
Sticker No.SE/96/017032
WHO SEARO NEW DELHI
£
I
?
"BIKALPA"
557, 4TH BLOCK, STH MAIN
KORAMANGALA, BANGALORE-560 034
(AUGUST 1996)
(contents )
c
SUMMARY
Q
01
INTRODUCTION
03
)
MATERIAL
(m
CRITERIA FOR DEFINING INFECTION & DISEASE
A.
B.
C.
ii)
iii)
iv)
v)
07
07
08
08
1
09
TUBERCULOUS INFECTION
09
1.
1.1
1.2
1.3
PREVALENCE
Prevalence in different areas
Prevalence by age and sex
Situation over a time
09
09
09
09
2.
2.1
2.2
INCIDENCE
Incidence over time by age and sex
ARI
09
09
09
i
n
07
07
Screening for bact. diagnosis
Definition of a case
Prevalence ratio by variation in
screening procedure in a survey
No. of bact. specimens and prevalence
Definition of x-ray active bact. negative case
RESULTS
A.
05
05
06
PREVALENCE OF INFECTION
INCIDENCE OF INFECTION
ARI
TUBERCULOUS DISEASE
0
(JV
I
04
B.
C.
D.
E.
PREVALENCE OF DISEASE
09
1.
1.1
1.2
1.3
RADIOLOGICALLY ACTIVE CASES
Area-wise prevalence
Age, Sex-wise rates
X-ray active bact. negative case rates
10
10
10
10
2.
2.1
2.2
2.3
2.4
2.5
2.6
2.7
BACTERIOLOGICALLY POSITIVE CASES
Prevalence rates
Age-Sex distribution
Prevalence by age-sex and method of diagnosis
Change in distribution with time
Bact. case prevalence & socio-economic dimensions
Culture : Smear positivity proportion
Bacterial drug resistance
10
10
10
10
11
11
11
INCIDENCE OF DISEASE
11
1.
1.1
1.2
INCIDENCE OF X-RAY ACTIVE CASES
Definition
Incidence rate
11
11
11
2.
2.1
2.2
2.3
2.4
2.5
2.6
INCIDENCE OF BACT. CASES
Definition
Age-Sex distribution
Incidence over a time
Proportion smear positive in incidence cases
Incidence of infection in relation to case incidence
Conclusion
12
12
12
12
12
12
12
3.
3.1
3.2
3.3
INCIDENCE BY EPIDEMIOLOGICAL GROUPS
Rate of incidence of cases by infection
Rate of incidence by radiological abnormality
Incidence in epidemiological groups
12
12
12
12
PROGNOSIS OF CASES
13
1.
1.1
1.2
PROGNOSIS OF PREVALENCE CASES
Fate
Natural dynamics
13
13
13
2.
PROGNOSIS OF INCIDENCE CASES
13
3.
3.1
3.2
TUBERCULOUS MORTALITY
Proportional mortality
Mortality rates
13
13
13
TUBERCULOSIS IN PAEDIATRIC AGE GROUP
13
1.
2.
13
14
PREVALENCE
MORTALITY
ii
F.
MORBIDITY & MORTALITY: SOCIO ECONOMIC CONSIDERATIONS
1.
1.1
1.2
1.3
1.4
1.5
1.6
STUDIES NOT SPECIFICALLY DESIGNED FOR ECONOMIC
INFORMATION ON POPULATION
Information prior to NSS
NSS
Tumkur Survey
BCG Trial
Other studies
Mortality
14
14
14
15
15
15
2.
2.1
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
SPECIALLY DESIGNED BY SOCIO-ECONOMIC CRITERIA
Wardha study
By age and sex
By literacy standard
By employment
By Income-group
By area and living standard
15
15
15
15
15
16
16
3.
TUBERCULOSIS AMONG THE WORK FORCE
16
DISCUSSION
1.
17
SUMMARY OF TUBERCULOSIS PROBLEM
2.
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
RELIABILITY IN SAMPLING : PROBLEMS IN EXTRAPOLATION
Sampling and stratification
Reconsideration on average prevalence rates
Infection
Radiological cases
Bact. cases
Current estimates on pulmonary tuberculosis
2.2.4.1 Estimates for Andhra Pradesh, South India
2.2.4.2 Estimate on patients on treatment
2.2.4.3 Estimate on morbidity and mortality from SEARO
workshop 1996
2.2.4.4 Use of estimates
3.
14
17
17
17
17
17
18
18
18
18
18
19
19
3.1
3.2
CHANGES IN TUBERCULOSIS SITUATION OVER A TIME:
ITS MEASUREMENT
Indices for measurement
ARI
19
19
19
4.
4.1
4.2
4.3
CONTROL PROGRAMME & EFFECT-EVALUATION
Objective of an Indian programme
Continued surveillance through ARI and effect-evaluation
Epidemetric models
20
20
20
21
•
iii
c
c
c
c
REFERENCES
I
FIGURES
)
22-26
1 -9
TABLES
1 - 14
APPENDIX
I-VI
ACKNOWLEDGEMENT
VII
iv
C
SUMMARY
The data available on tuberculosis morbidity and mortality from various surveys in India are
summarised in this review, with a consideration of their socio-economic aspects. A brief
interpretation of the epidemiological situation in India, along with the use of the information on
epedemiology in designing the tuberculosis programme in India (NTP) is given in Appendix (vi).
1.1.
Tuberculosis problem is more or less spread all over the country. Differences in prevalence
rates of disease as observed between area to area did not appear to be statistically significant
(barring a few exceptions e.g., Tamil Nadu, Raichur and urban slums as in Calcutta).
Prevalence rate of disease was observed to be the same for the rural and urban areas (Fig.5).
1.2.
Of persons in all ages both sexes about 38% were infected. In males, almost 70% of persons
above 40 years of age were infected. About 2% had pulmonary tuberculosis, but only 0.4% could
be the average prevalence rate of bacillary cases (in 5+ age group). Mortality rate was observed
for the last time in a population survey way back in 1966. It was reported to be about 90 per
100,000 (could be half of that, as hypothesised in recent times).
1.3.
Prevalence rates of infection, disease and mortality were more in males than in females:
a third of the cases in all ages could be females. However, of cases in females, about half could
be in the child-bearing age.
1.4.
In a rural area in Bangalore, there was a marginally decreasing trend in the infection rate:
about 2% per year over a long period of observation ranging from 5 to 25 years, among children
(Fig 3). But the same was not seen in the adjoining areas of Tumkur, Doddaballapur and in the
neighbouring state of Tamil Nadu (the last, over a 15 year period).
1.5.
Pulmonary tuberculosis is an adult disease. Population in 0-19 years (comprising about 50%
of total population) could be estimated to contain only 7% of total prevalence cases. Remaining
93% of cases could be distributed in population aged 20 years over (Fig.6). Relatively higher and
higher concentration of cases in higher age groups was observed in later surveys as compared
to earlier surveys in Bangalore rural area. In later surveys conducted in 1984 in Bangalore rural
areas, about 80% of cases were detected among those in 40+ age group as compared to about
50% in earlier surveys (Fig.8).
1.6.
Prevalence rates of cases had shown almost no change over a period of over 20 years
from different surveys in different areas (Table 9 & 10).
1.7.
The incidence of cases was observed to be a third of the prevalence, on the average,
which could be interpreted to be due to failure of intervention and pooling up of previous cases.
The incidence of smear-positive cases was estimated to have dwindled in 23 years in Bangalore
rural area from around 0.65 to 0.23 per 1000 (Table 15). No such observation was made elsewhere.
1.8.
Nearly 10% of all causes crude mortality in the community was contributed by death due
to tuberculosis (tuberculosis mortality rate: about 90 per 100,000). The highest proportional mortality
in women in the reproductive age could be attributed to be due to tuberculosis, higher than even
that due to peri-natal causes. Nearly 40% of female population being in the age group of 20-44
years, this could amount to be the highest single cause of death in women in this vulnerable
population group.
1
1.9.
Mortality rate due to tuberculosis was observed to be considerably lower than case rate,
and was decreasing with time from survey to survey. The case rates were considerably lower than
the infection rates (mortality rate: case rate: infection rate ::90:400:38,000 per 100,000). The
observed wide gap between the rates has significance with respect to the age of the epidemic
(Fig. 15). The survival rate of cases diagnosed in later surveys were better, compared to that in
earlier rounds of longitudinal surveys.
1.10. Paediatricians were generally seeing less of miliary, meningeal and fulminant forms of
tuberculosis. Occurrence of pulmonary tuberculosis in paediatric age-group was minimal (Table
17). However, children in 0-4 year age group was found to be highly vulnerable in a Madras slum,
having conspiculously high mortality to tuberculosis.
1.11. There was a higher prevalence in 'Kutcha' houses than 'Pucca' houses, the former
inhabitated by the poor. There was an observed association of pulmonary tuberculosis with lack
of education, lack of regular source of income as well as per capita income. Of the workers with
tuberculosis, it is recently estimated that about 52% are in the 15-44 years age group (Table 18).
In this age group, the proportion of women among the urban workers with tuberculosis (40.0%)
was estimated to be higher than among the rural (17.9%).
1.12. The rates observed in the various surveys conducted in India, have been used to estimate
the approximate average number of cases and deaths etc., in the country, to serve as a guide
for planning for the resources for a programme at the National level (Table 19). The numbers
presented in brackets in the table are estimates, revised in the light of more recent observations.
The likely estimate of disease in India could be on average; Bacteriologically (culture) positive
cases 4.4 million (0.6%), Radiologically active bacteriologically negative 2.3 million (0.3%), and
annual tuberculosis mortality 0.42 million (45/100,000).
2
l
c
L INTRODUCTION
I
In line with the current scientific development and WHO policy1. Govt, of India, had in the recent
years, re-examined the strategy hitherto followed under the National Tuberculosis Programme
(NTP)' A revised NTP is currently being formulated with assistance from the World Bank and the
WHO2. While re-defining the strategy and deciding on the priorities/emphasis on programme
activities as well as their scope, the epidemiological aspects of the disease, peculiar to this
country, have to be kept in mind. For Instance, because of its recognised predilection for affecting
the relatively underprivileged segments of the society3, a control programme addressed to the
needs of the country, requires also to evaluate the relevant data with particular reference to the
socio-economic and gender differentials, if any. The current report is prepared in this context,
reviewing the tuberculosis situation in India. The data could be made use of not only for planning
but also evaluation purposes, generating fresh thinking In respect of epidemiologic dimensions of
control programmes, especially keeping the circumspection of some of the noted programme
managers in view4.
Considering the infectiousness of the pulmonary forms of the disease, the present report confines
itself to the data on pulmonary tuberculous and tuberculosis infection only. Available data, both
published as well as unpublished to the extent available, are relied upon to present:
1.
Prevalence and incidence of tuberculosis infection as well as of sputum positive and
sputum negative pulmonary tuberculosis, by age and sex.
2.
Prevalence of tuberculosis infection and disease by socio-economic status of population.
3
c
IL MATERIAL
The review mainly derives its material from the published sources, originating from some of the
leading tuberculosis research institutions of the country. However, wherever required, unpublished
work from these institutions have also been freely referred to. Apart from the main papers
originating from some of these studies, a considerable number of subsidiary papers were published
as well. These have been referred to in the text, as and when required.
Other lesser known organisations have, especially in comparatively recent times, carried out some
significant research; a few of them still to be published. These have been duly evaluated and
referred to, if found authentic enough! The major research efforts in epidemiology of tuberculosis
are described briefly in Table 1, giving the name of the study, reference, year of study, population
represented, the design and methodology (age group studied, population-screening and
diagnostic methods used).
4
(111. CRITERIA FOR DEFINING INFECTION AND DISEASE^
(A)
PREVALENCE OF INFECTION
The estimate of prevalence of tuberculous infection in the community is based on the
interpretation of the results of tuberculin testing of persons without BCG scar. The indurations,
measured ideally, between 48 and 96 hours of the tests, are distributed in the form of a histogram
(FIGURE-1). From these distributions, it is possible to demarcate the positive reactors from those who
are negative to the test dose, since the Indurations tend to lie around two discernible modes
separated by a dip, called the antimode. The nature of distribution of the indurations however
differ to an extent from study to study, depending on the tuberculin (or antigen) used, their
dosages, testing and reading variations, as well as on cross-reactions on account of the
non-specific sensitisations that may be present in a given area due to environmental factors
(including non-tuberculous mycobacterial sensitisations). In fact the dip between the two modes
is sometimes less recognisable due to a high prevalence of non-specific reactions in India,
especially south lndia6)'23,32. Due to these problems, it is not possible to have a uniform size of test
reaction identified with tuberculin test positivity in every survey.
Besides the type of tuberculin and their dosages used form survey to survey not being the same,
the problem of defining the infected is compounded by the changing levels of demarcation
between the infected and uninfected from one survey to the other10,12. The problem of changing
demarcation levels from survey to survey had no doubt engaged the attention of researchers12,33.
It is suggested after a field study that the demarcation line between the infected and
non-infected persons would require to be shifted from survey to survey to take care of the
observer variations or the rising proportions of BCG scars in the population being wrongly classified
as unvaccinated from one survey to the next, thereby affecting the classification between the
infected and uninfected33. It is not intended to go Into more detailed analysis here owing to
space-constraint.
For this review, persons are considered as infected, if the indurations to tuberculin test are
observed to lie to the right of the demarcation line as decided on the basis of the distribution of
the indurations, for the given study.
Non-specific sensitivity: Frimodt Moller had recognised that there could be two kinds of infection
in south India ('specific' and 'non-specific1) and that it could have serious implications in
understanding infection risks6. The prevalence of the non-specific infections were hypothetically
considered to be due to other mycobacterial infection. Chakraborty et al had shown that the
non-specific Infection increased with age, so much as to leave only a small proportion of the
population in the age group 15-24 years without any kind of sensitivity to tuberculin32. Figure 2
shows that in the age group 15-24 years, where the proportion infected with Mycobacterium
tuberculosis was 33.2%, of the uninfected 93.4% were showing evidence of other Mycobacterial
infection. Raj Narain had shown its prevalence to be widespread in some areas23.
Thus the interpretation of the tuberculin test results in older age groups could be unreliable owing
to a high prevalence of non-specific sensitivity.
5
(B)
INCIDENCE OF INFECTION
'The results of tuberculin testing surveys are usually presented only in the form of prevalence figures
for past tuberculous infection. Prevalence figures do not indicate, when in the past the first
infections had occurred34. Incidence of infection, which gives the most recent tuberculosis
transmission situation in the community, is defined as the number of fresh infections occurring in
the community between two points in time, among those uninfected initially. It calls for direct
measurement of the conversions of uninfected persons to infected status, in the intervening period
between two succeeding surveys, say a year or so apart. Information on incidence from some of
the surveys in India are reviewed here 6'10-15'35.
Apart from the operational constraints In carrying out the incidence surveys on tuberculous
infection again and again, there were inherent problems in interpreting the repeat test results36.
The latter was proposed to be solved by distributing the differences between the two tests in each
individual. In younger age group, where the situation was not likely to be complicated by high
non-specific sensitivity etc., the distribution was found to be bimodal, the antimode separating the
'new infected' (occurring to the right of the antimode), from those who were 'not newly infected'
(to the left of the antimode). In the BCG TRIAL for instance, the antimode was at 12 and 10mm,
between the initial test and at retests at 21/2 years and 4 years respectively16. Thus persons showing
more than 12 and 10 mm increases over the first test Induration size, when retested after 2,/2 and
4 year period respectively, were identified as freshly infected in BCG.Trial. Somewhat similar
method was adopted for NTI.LS10.
Annual Risk of Infection (ARI): The problem of obtaining data on incidence of infection could be
obviated by computing these from one or more prevalence figures, if these are obtained by
similar testing methods and if the prevalence surveys ’cover a range of ages'34. The computed
estimates of the incidence, called the 'Annual Risk of Infection^ARI), give the risk of tuberculous
infection in successive calendar years. These estimates may be regarded as an alternative
method of presentation of the tuberculin surveys. ARI could be defined as the proportion of the
population which will be primarily infected or re-infected (in those previously infected) with
tubercle bacilli in the course of 1 year, and is usually expressed as a percentage or as a rate. A
tuberculin survey carried out in a representative sample or a succession of them could be
converted into the estimated risks (ARI). The ARI at a particular time indicates the current
magnitude of the incidence and prevalence of infectious cases as well. An observed decline in
the ARI would be the earliest Indicator of a decline In the epidemic cycle of tuberculosis and
would therefore be a suitable indicator for evaluating tuberculosis control programme. A rising
risk on the other hand could be the portent for a change to the other direction consequent on
adverse epidemiological situation e.g., HIV supervening.
The ARI could generally be worked out on the basis of the method described in TSRU Report34 22.
By this method, the ARI (R) for a group of average age (A) was derived from the prevalence (P)
by R= 1-(1-P) 1/A
Incidentally, the corroboration that ARI represents annual incidence of infection is available from
the study by Chakraborty et al in the LS-Follow up13(Figure 3).
6
(C)
TUBERCULOUS DISEASE
(i)
Screening for bacteriological examination: In the classical epidemiological surveys for
estimating the case-load, the population Is x-rayed at first, mostly using a mobile mass miniature
radiography (MMR) unit. Only the persons with shadows on MMR of chest assessed as abnormal,
usually by two readers independently, are subjected to sputum test (x-ray-screening). Alternatively,
the persons in the community are questioned for presence of chest symptoms (cardinal chest
symptoms being cough, pain chest and fever of one or two weeks duration and haemoptysis);
those having symptoms (symptomatics) are subjected to sputum examination
(symptoms-screening). In the MS, NSS, TUMKUR STUDIES, NTI-LS, BCG-TRIAL and NEW DELHI STUDY,
the x-ray screening procedure was adopted6-7-8'910'15-21 (Table 1). On the other hand, in the
WARDHA, RAICHUR, TRC-TRIBAL and CARNICOBAR Studies, symptoms-screening procedure was
followed25-26-27,28. In the NTI.PERI URBAN STUDY and LS-FOLLOW UP, again, the population was
screened for their eligibility to undergo sputum examination, using a criteria, different from the
above mentioned two, and casting a wider net14,24.
Varying screening procedures from survey to survey affect the observed prevalence rates and
therefore the comparability of results between one survey and the other36-37.
(ii)
Definition of a bacteriological case: It was shown that cases positive by smear alone,
detected in an epidemiological survey, were hardly the real cases of tuberculosis, the
reproducibility by a second smear or by way of radiological confirmation as active TB in these
cases being very poor15,38. In the BCG-TRIAL, of the 567 persons positive on smear but negative on
culture, 76% had only 1-3 bacilli on both smears examined. The x-ray confirmation in these persons
having actively tuberculous pulmonary shadows was a mere 13%15. Cases with positivity on culture
only, without radiological abnormality at the corresponding survey, were also a group whose
tuberculous etiology was not acceptable in the NTI-LS11. In most of the epidemiological surveys
carried out at the NTI using the classical survey method, a case of tuberculosis was defined as a
culture positive person, with a radiological abnormality at the current survey”. Persons not
confirmed on culture (i.e., smear alone positive) were not defined as bacteriologically positive
cases, even if they had an x-ray-abnormality, (they were however eligible to be defined as x-ray
positive cases, if shadows on their chest-radiography were classified as actively tuberculosis).
Three categories of bacteriologically positive cases were presented in the BCG-TRIAL: (i) positive
on two cultures (ii) positive on one culture-(iii) smear-positive, excluding those showing 1-3 bacilli.
There was, of course, the additional group of radiologically positive bacteriologically negative
group15. In the NSS, the sputum was collected contingent on an abnormal shadow being present
on chest x-ray. It appears that the definition of a bacteriological case, under NSS and NTI classical
surveys were, essentially similar. In the Madanapalle study, on the other hand, there was too much
stress on radiological examination, bacteriological results being comparatively of less prominence6.
(iii)
Variation in screening prodecure and diagnostic test influencing prevalence rate: In some
of the more recent prevalence surveys carried out in India, mobile MMR units were not employed
to screen the population (MMR-screening). An alternative method of screening the population
was followed in order to identify the population eligible for sputum tests, by questioning the
persons on the presence of cardinal chest symptoms on a house to house basis, followed by
sputum tests, either culture or smear microscopy24,25'26'28,30.
A recent NTI-study, addressing itself to the problem of comparability of culture positive prevalence
rates obtained by employing population-screening by MMR vs. symptoms questioning has shown
that the efficiency of the above two screening procedures in diagnosing culture positive cases
was different from the best estimate obtained of employing multiple screening (MMR and/or
symptom question)24 The correction factor to obtain the best estimate of culture positive cases
7
I
from that obtained on symptoms screening could be between 1.30-1.63 (approximately 1.5).
However, the significant finding from this study, which to an extent seemed to extenuate the
problems of estimating cases based on variable screening procedures, was that the prevalence
rates of the culture positive cases in the community were the same, irrespective of whether
symptoms or MMR screening was the procedure of choice in screening the population for
identifying the eligibles for sputum test. The same was found to be good even for the estimates of
smear positive cases. Moreover, it was observed that there were no age-sex wise differences in
observed rates between the two procedures. It was immaterial for the estimate on the basis of
symptoms screening, whether the interviews of the population for Identifying symptomatics was
carried out by a qualified social investigator or a field health worker, as long as adequate training
on the procedure was given prior to the deployment for the investigation. The above could be
utilised in evaluating and drawing inferences from some of the latest studies on prevalence.
(iv)
No.of bacteriological specimens examined and prevalence of cases: The number of
specimens of sputum collected from among the eligibles after screening were variable from survey
to survey, which would affect the estimate of the bacteriologically positive cases in the
community. The extent of difference in rates could be estimated from the finding, that instead of
two sputum specimens, if four were examined in a survey, nearly 25% more number of cases could
be added to the prevalence39. This was found to go as high as 39%, when eight specimens were
examined37. Needless to say that the findings from surveys with variable number of sputum
specimens need to be suitably revised, before comparative assessment of the rates are made.
(v)
Definition of a radiologically positive bacteriologically negative case of tuberculosis: Apart
from its use as a screening tool for the identification of persons eligible for bacteriological
examination In a tuberculosis survey in the community, MMR-results are also relied upon to
diagnose and label persons as radiologically positive cases of pulmonary tuberculosis ('persons
with active and probably active shadows'-NSS). Estimates of the problems of tuberculosis on this
basis has some serious limitations, principally owing to the inherent 'reader-variations' in
interpretation of the x-ray shadows (as well as their identification) their tuberculous etiology as well
as the activity. The procedure, usually followed, was to have two independent interpretations of
the chest x-ray shadow on MMR (single picture) and to collect sputum from persons with a
shadow ('x-ray-screening1). The disagreements between the two independent interpretations were
then subjected to a third reader's assessment (or, an umpire reader's arbitration) regarding the
nature and etiology of the shadow. However, despite the panel of readers, used in these surveys,
being composed of highly experienced persons in their field, there was considerable disagreement
in interpretations15.
A five-year follow up of the persons, diagnosed to have active tuberculous shadows (as also other
MMR abnormalities in their chest), was carried out by repeated x-ray of chest, smear exam for AFB
and culture for M.tuberculosis (three examinations at 1 ’Zz, 1 ’Z? and 2 years after the initial one)40
Based on an overall consideration of all the follow up investigation results, at one time, a panel
of x-ray-readers had jointly re-evaluated the initial MMR-interpretations (Joint Parallel
Reading-J.P.R.). Of the initial 385 sputum negative x-ray active persons identified initially, only 22.0%
could really be classified to have sputum negative x-ray active tuberculosis at the first survey,
when such a re-evaluation of the MMR-shadows was carried out by J.P.R.40. Unpublished
information from the TRC Madras on the BCG.TRIAL FOLLOW UP studies recently corroborated this;
not even a third of the radiologically positive cases were later assessed to be having active
tuberculosis needing treatment41.
It could be suggested that the generally accepted prevalence rate of radiologically active
bacteriologically negative pulmonary tuberculosis in India, largely estimated on the basis of data
from the NSS and other similar studies (using a single MMR and the pulmonary shadows evaluated
by 2 readers and umpire), could be nearly three times the likely estimate of the problem.
8
c
IV. RESULTS
(A) TUBERCULOSIS INFECTION
(PREVALENCE AND INCIDENCE)
1.
PREVALENCE OF INFECTION
1.1.
Prevalence in different areas (Tables 2 & 3): That the tuberculosis infection was more or less
spread throughout the country was hypothesised on the basis of studies done by Ukil and from
information available from the mass BCG - Campaign results42. However, differences were
observed from area to area, e.g., hilly areas. In later surveys carried out in parts of India, different
epidemiological situations could be observed between areas in adjoining states (Tamil Nadu and
Karnataka)1015, contiguous districts in the same state (Tumkur and Doddaballapur in Bangalore
district)8,22 and between areas within the same district (economically backward northern part of
Tumkur compared to the southern part: infected, 46.0% and 30% respectively8), as also between
two panchayat unions of Tiruvallur district in BCG.Trial: Infected 1-9 year old, Kodambathur 8.7,
Thiruvalangadu 12.3 percent in 197916 (Not on Table). Prevalence by socio-economic criteria is
presented separately under Section IV F (see infra).
1.2.
Prevalence by age and sex (Tables 2 & 3): Between 25-38% of population in all ages both
sexes were infected, as per data available from Tumkur Study (males 42.8, females 33.9 per cent)
(Not on Table)8, infection rising with age, more in males (Fig.4)6-810. Prevalence rates were almost
similar in males and females upto about 14 years in age, after which males had higher
prevalence. Whereas the peak in the males was observed at around the age of 30 years, it was
so in females by about 40. Similar phenomenon was observed both in Tumkur, as well as in the
BCG Trial area (Not presented)16. In the BCG.Trial overall prevalence was found to be 50% (males
54.0, females 46.0%)16.
1.3.
Situation over a period of time: There was a declining trend in prevalence with time in
NTI.LS area (Appendix table i), not seen elsewhere.
2.
INCIDENCE OF INFECTION
2.1.
Incidence by age, sex and over time: The incidence of infection was found to be 1% per
year and did not seem to vary age-wise in 0-4, 5-9 and 0-14 year age group in the NTI.LS (Table
4)10. In rural areas of Bangalore there was a marginally declining trend observed over a period of
5 years (Fig.3)10.
2.2.
A.R.I.: ARI calculated from different parts of the country was found to be between 1 and
2% (Tables 5 & 6). The decline In Bangalore area at about 2% per year annually for over 23 years,
as seen in Figure 313, was not seen elsewhere, including in BCG.Trial area over 15 years period of
observation11.
(B)
PREVALENCE OF DISEASE
This report confines itself to pulmonary tuberculosis. No significant population-based study on extrapulmonary TB is available, except study on glandular forms in small population groups of Nicobar
Island and Sheriff garden in Bangalore 28'54. Being in specific and selected groups, data from them
could not be representative.
9
1.
RADIOLOGICALLY ACTIVE CASES:
1.1.
Area-wise prevalence: Table 7 presents the prevalence of pulmonary tuberculosis,
including bacillary cases, across the country from NSS data. Table 8 presents the bacteriologically
negative radiologically active case prevalence, derived from it. Tables 9 and 10 present the rates
from limited area surveys conducted after the NSS. Prevalence rates of disease did not appear
to be significantly different from area to area, whether rural, semi-urban or city. There were
however pockets of high prevalence, possibly related to economic situation. For example, the
prevalence rate of 58 and 50 per thousand in Block No.39 and 8 Calcutta city (slum-dominated)
was higher than 2.48 per thousand in Block No.34. Similar was the case with Delhi city.
1.2.
Age-Sex-wise rate: The rates were seen to be rising with increasing age in both sexes,
irrespective of areas of study (Fig.5).
1.3.
Radiologically active abacillary case-rate: The bacteriologically negative radiologically
active case prevalence rate varied from 10-19 per thousand. These could be over-estimates to
the extent of about 75% (See section III C.V.),40. The rates, after correcting for possible
over-estimates, is presented in the last column of Table 8. The NTI-rural study which had followed
the JPR method of interpretation of MMR and the Madanapalle study, also following a similar
method, had reported prevalence rate of 5.40 and 4.23 respectively (Table 9)440'43.
2.
BACTERIOLOGICALLY ACTIVE CASES:
2.1.
The prevalence rates are presented In Table.7 (for NSS), Table.9 (for, limited area studies
using MRR-screening) and Table 10 (for, limited area studies with symptom-screening). There was
no difference between the rates, either from area to area or with time, provided the same method
and criteria were followed. It should be appreciated that large sample sizes of population are
required to be followed up. so as to be able to discriminate small differences in the already low
case-prevalence rate of about 4.0 per thousand44'’7 (Appendix Table ii).
2.2.
Age-sex distribution: Figure 5 shows age, sex distribution by areas. The rates rose with age
in both sexes, more in males. Based on the age-distribution of the cases, it could be estimated
that the population in 0-19 years age (comprising 50% of total) could contain only about 7% of
total prevalence cases (Fig 6). Remaining 93% of the cases could be found distributed in the
population aged 20 years and over (i.e., in remaining 50% of population). On the other hand, of
the total cases, nearly 50 per cent could be distributed among the population aged 40 years and
over, constituting about 20 per cent of the total population.
Prevalence of bacteriological cases in each of the age and sex groups studied, is presented in
Table 11, as computed on the basis of BCG.Trial. Prevalence in each of the age groups was much
less in females. Of the total bacillary cases 79.0% could be in males and 21% in females in
BCG.Trial, Whereas males in 20-54 years age group i.e., the wage-earners, had constituted 39%
of total male population, nearly 70% of all male cases were in this age-group. For females, on the
other hand, the population in the reproductive age group of say 20-44 years, had constituted
nearly 40% of the total female population, with about 56% of all the female bacillary cases
distributed in this age group.
2.3.
Prevalence by age-sex and categories of case: Figure 7 presents the distribution of cases
by criteria of diagnosis and by age/sex. The prevalence of cases was lower among females than
among males and increased with advancing age in males. Whereas prevalence of bacillary cases
had more or less reached its peak in females by about 40-49 years, it had continued to rise for
radiologically positive cases in both sexes in BCG.Trial.
10
2.4.
Change in distribution with time: The observed age-sex distribution of cases with time in the
NTI.LS area was seen to reflect a change In situation as shown In Figure 847. In the first of the
longitudinal surveys in Bangalore rural area, about 50% of cases was found in the population
above 40 years in age, constituting about 20% of total population. About 43% of the cases were
distributed in 20-39 year age group, constituting about 39% of population. In later surveys in the
same area, about 70-80% of cases were found among those In 40+ age group. Relatively higher
and higher concentration of cases was observed to take place in higher ages in later surveys.
2.5.
Bacteriological case prevalence and socio-economic dimensions: Table 12 along with
Appendix Table (iii) and (iv) present the various socio-economic categories in the population and
prevalence rates in them along with the proportion of cases contributed by each to the total
prevalence cases in the community25. These aspects are dealt with separately under Chapter F
(see infra) of this Section.
The Wardha study25 and the NTI.peri -urban study24 had shown, that as different from other studies,
the rural areas had higher prevalence rates. The respective rates per thousand were:- Wardha
study: Urban 1.62, Rural 1.98, NTI.Peri-urban: 3.4 (interval estimate 2.7 to 4.2) as compared to
Bangalore rural 5.7 (interval estimate 5.4 to 5.9). Whether the differences were due to
urban-perl-urban and rural divide or had represented a favourable trend In favour of the urban
group is a matter for discussion.
2.6.
Culture: Smear positivity proportion: Table 13 shows the data from NTI.LS14.lnspite of the
fact that there was no difference in the age standardised case-prevalence rates from survey to
survey in the area for a 23 year period, the smear positivity among the prevalence cases had
come down to 16% at the survey in 1984, from the initial proportion of 47.0% observed in 1961.
More importantly, notwithstanding a very comprehensive screening method in the 1984 survey,
the smear positive case prevalence rate had also come down to 68 from 189 per 100,000,
observed in 1961 survey. It Is debatable, whether this could be attributed to the National
Programme, implemented in the area after the Survey 4, in 1970. The trend may be the result of
a low-efficiency programme running over a long term in the area14 In other surveys conducted
elsewhere in India, the smear positivity proportions were more or less similar to NTI.LS first to fourth
surveys (e.g., Bangalore Peri-urban area 44.9 to 46.7%24, survey 1 of BCG.Trial 57.4%16).
2.7.
Bacterial drug-resistance: Table 15 and Figure 9 shows the bacterial drug resistance in the
community. Unpublished information from New Delhi TB centre, Bangalore Peri-urban area and
rural area in Raichur (Karnataka) shows high initial resistance to INH in recent times.
(C)
1.
INCIDENCE OF DISEASE
INCIDENCE OF RADIOLOGICALLY ACTIVE CASES
1.1.
Definition: Sputum negative persons with a normal MMR of chest or those with
non-tuberculous or inactive tuberculous shadows at the initial survey, who had a radiologically
active tuberculous shadow at a later survey, but sputum was negative, were classified as
incidence of radiologically active bacteriologically negative cases (also called "suspect cases").
1.2.
Incidence rate: In the NTI rural area study, of 35,876 persons aged 5 years and over,
incidence was found to be 2.24 per thousand between two points of observations in 3 months on
JPR43 (not on table). The Incidence rates, as calculated for 3 months, was not different from that
estimated for one year44.
11
f
(
)
2.
INCIDENCE OF BACTERIOLOGICAL CASES:
those witoout
without a raaioiogicai
radiological opacny
opacity in u
a pievioub
previous
2.1.
Definition: Culture negative persons or rnose
survey, who were detected to have culture positive disease at a later survey, were termed as
"bacillary case incidence" between the two surveys40. The respective incindence rates expressed
as an annual average between two surveys are available from New Delhi, NTI.LS and BCG.Trial
areas20'21'1018. On the other hand, new cases detected in the community following continued
surveillance are reported from Nicobar and CMC-Vellore studies 28 45 (Direct observation of
incidence).
2.2.
Incidence of cases and age-sex distribution: Table 15 shows the incidence from various
surveys in India. Age-Sex distribution of incidence cases over a 5 year period is shown in Figure 10.
The incidence in BCG.Trial area was higher than elsewhere, as it was for prevalence also. On an
average, incidence of cases between two points of observation however, was a third of the
prevalence at the initial point of observation, similar to that in NTI.LS. In the NTI.LS about 50% of
total incidence was observed to be in males aged 35 years and over. In females the contribution
was 15%1011.
2.3.
Incidence of cases with time: In the NTI.LS, among the younger population in the age group
5-4 and 15-34 years, a decrease with time was observed, with corresponding rise in those aged
35+ years1011.
2.4.
Proportion of smear positivity in incidence cases: The proportion in incidence cases,
positive on culture alone (negative or smear), in relation to culture and smear positive cases in the
NTI.LS was 75.0% and 55.8% for surveys 2 to 3 and 3 to 4 respectively (not on table)1011. The
incidence of smear positive cases was estimated to have declined in 23 years in the NTI.LS area
from 0.65 to 0.23 per 1000 (not to table)14 No such observation was made elsewhere.
2.5.
Incidence of infection in relation to that of casesJable 4 shows, that the relationship of
annual incidence of infection of 1% as observed in various age groups upto 14 years,
corresponded to smear positive case incidence of 45/100,000 in survey 1 of NTI.LS1011, and in line
with observations made elsewhere49. However, the relationship was not stable in later surveys of
NTI.LS (not presented).
2.6.
Conclusion: The considerably higher prevalence of cases as compared to incidence (3:1)
could be interpreted to be due to failure of intervention and consequent pooling of previous cases
in the community.
3.
INCIDENCE OF CASES BY EPIDEMIOLOGICAL GROUPS:
Case incidence by infection: Figure 11 depicts a higher rate of case incidence among the
3.1.
infected, rising with age, especially in males.
3.2.
Case incidence by radiological abnormality: Bacteriologically negative persons having
radiologically active tuberculous shadows had the highest incidence rate of bacillary cases (2.6%
per year), on a five year observation, more so if they were tuberculin positive11.
3.3.
Incidence of cases by epidemiological groups: Various population groups, classified by
some epidemiological attributes, and incidence of cases in them, are presented in Figure 1250. The
two highest risk groups had constituted only 5.6% of the population size, but still contributed 46%
to the total new cases arising in the population in a year. However, one must also balance it with
the observation that 48% of the new cases would arise from amongst those who had no shadow
in their chest x-ray, albeit, with a much lower rate, and was attributable to the relatively larger
12
group size (89% of population). It could be concluded that surveillance of the two highest risk
groups could be useful, it they were action-taking50.
(D)
1.
PROGNOSIS OF CASES
PROGNOSIS OF PREVALENCE CASES:
1.1.
Fate: Fate of cases in a situation without active intervention is presented in Figure 13. Based
on 1 1/2 year period observation, 20%, 18% and 62% of the cases were dead, became sputum
negative and remained sputum positive respectively, in a year's time, subject to the hypothesis
that the dynamics within the I1/? year period, had remained uniform.
1.2.
Natural dynamics: Figure 14 is a stylised presentation of the dynamics of tuberculosis in the
community without active intervention, • utilising the Information available from NTI.LS47. The
proportion excluded annually from the existing pool of cases by reasons of death and cure, was
rounded up to be nearly a third of the Initial pool (d:20%, c:18% of pool, total: say, 1/3 of pool).
The exclusions would get balanced with the estimated addition by way of annual incidence (i:
to the extent of about 1/3 of size of initial pool). Thus, year to year, the size of the pool would
remain unaltered, and 2/3 of it would be formed by the continuing cases (the so-called "left
overs"51).
2.
PROGNOSIS OF INCIDENCE CASES:
Of the incidence cases in the NTI.LS between surveys 1 and 2, the proportion of dead, cured and
remained positive were 14%, 52%, 33% respectively, thus having a better prognosis than that in
prevalence cases11 (not on table).
3.
TUBERCULOSIS MORTALITY:
3.1.
Proportional mortality due to tuberculosis: Nearly 10% of all causes crude mortality in the
community was shown to be due to tuberculosis in the NTI. LS area (Table 17)52.
3.2.
Mortality rate due to tuberculosis in the community: Mortality rate in the NTI.LS area was
reported to be 95/100,000, not changing with time in 5 years (1961-68)52 (Table 17). In the New
Delhi area, between 1972-76, the rates were about 40 per 100,000, consequent on a well
organised programme20,21. In the Madanapalle area, the mortality was reported to have declined
from 253 (in 1949) to 64 (1952-53) and then to about 21 per 100,000 (in 1954-55), the latter
hypothetically attributed to be due to a well-organised programme6. Murray C.J.L, in his draft trip
report (Geneva WHO CDS 1992) estimated that women In their reproductive age (15-44 years)
had about 70,000 deaths from tuberculosis, every year, higher than that attributed to peri-natal
causes related to pregnancy and child-birth (un-published). Further, unpublished report derived
from the Sample Registration System (SRS), and available with the TB section. Government of India,
estimates around 400,000 annual deaths from tuberculosis in India. The currently estimated
mortality due to tubercuolosis could be in the range of 50-80 per 100,000 i.e., between 0.3 to 0.5
millions annually (say 0.4 millions).The above projection agrees with that by Dholakia 53.
(E)
1.
TUBERCULOSIS IN PAEDIATRIC AGE GROUP
PREVALENCE:
Pulmonary tuberculosis in children was reported to be less of a problem in the paediatric
population as compared to those aged 15 years and over5455. Table 17 presents prevalence and
incidence of cases from NTI.LS, upto the age 14 years. Average rate of incidence of
bacteriologically positive cases among children was ]/5 of prevalence, whereas it was ]/3 in those
13
aged 15 years and over. In the Nicobar study the best estimate of all forms of tuberculosis in
children was 0.6%, including histo-pathology confirmed glandular tuberculosis (smear positive case
prevalence 0.4%)56.
2.
MORTALITY:
In a study by Rajnarain and Diwakara, considerably higher annual mortality rate was reported from
a Madras urban population group aged 1 -4 years old (239 per 100,000) as compared to between
52-55 in the rural areas under BCG-Tiral and NTI.LS57. Of the total causes deaths in that age group,
nearly 50% were estimated due to tuberculosis, as against between 4 and 5% in the rural areas
in the same age group. The study had concluded that the special risk pertained only upto 4 year
of age and not beyond.
(F)
1.
MORBIDITY AND MORTALITY: SOCIO ECONOMIC CONSIDERATIONS
STUDIES NOT SPECIFICALLY DESIGNED FOR ECONOMIC INFORMATION ON POPULATION:
Information prior to NSS: Not much reliable information on infection by socio-economic
1.1.
criteria are available in general. It was however known from BCG vaccination campaign results,
upto early 1950s, that the infection rates were higher in Industrial towns than elsewhere - 50 per
cent of those aged 10 years and more and 75 per cent of those 15 years and more were
infected7.
1.2.
NSS: In the NSS the only information collected on the economic strata of the population
was place of residence (urban/rural) by type of dwelling houses ("Kutcha'7 "Pucca" houses)7. In
the cities, there was higher prevalence of disease (x-ray active as well as bacillary) among persons
living in the "Kutcha" houses than in the "Pucca" houses. The differential in prevalence rates by
type of houses did not exist in rural areas. It was taken to indicate the possible effect of economic
and sanitary conditions. The NSS had also shown that there were areas within a city (as in
Calcutta), where the prevalence of tuberculosis was as high as 40 or 50 per thousand. These areas
were invariably inhabitated by the poorest segment of the population. For example. Block 39 and
8 of Calcutta city had prevalence of 58 and 50 per thousand respectively, against 2.48 per
thousand in Block 34 (comparatively affluent) as being the lowest estimate. Delhi city also had
several blocks with prevalence between 30 and 50 per thousand, and so had other cities too in
every zone.
Even though, generally speaking, the bacillary case prevalence rates in urban and rural areas
were similar within each zone. Bangalore city, forming part of the Madanapalle zone, had a lower
prevalence (2.40 per thousand; confidence limit 1.64 - 3.16) than the rural areas of the zone (6.11
per thousand; confidence limit 5.02 - 7.20). In all likelihood. Bangalore being one of the
economically betterof cities, with considerably less slum problem within its environs, had something
to do with it. The information is further substantiated by the observation in recent times that a
sample population of Bangalore peri-urban area had a lower case prevalence rate than found
in the sample survey conducted in the Bangalore rural areas24.
1.3.
Tumkur Survey: The tuberculosis prevalence study in Tumkur district, which had immediately
followed the NSS had, as one of its objectives, to investigate the area-wise difference in
tuberculosis case-rates8. It had made the significant observation, that the southern half of the
district, consisting of six subdivisions (talukas), had "strikingly" large differences in the tuberculosis
situation over the southern four talukas. (Tuberculous infection rate all ages: Nothern half 46,
Southern half 30%. Prevalence of x-ray active cases: North 2.3, South 1.4% and Prevalence of
bacillary cases: North 0.58, South 0.24%). Moreover, there was a preponderance of male bacillary
cases in the north than in the south. It is well known that the northern part of Tumkur district is
comparatively backward than the sourthern areas studied. There was no difference of course due
to coverage by age, sex or due to size of villages between the two zones in the study, to which
the differences could be attributed.
14
1.4.
BCG Trial: In the Chingleput study of BCG.TRIAL there Is the consistent finding, that in terms
of prevalence of infection, the problem of tuberculosis was higher in Thiruvalangadu area as
compared to Kadambathur area, the annual risk of Infection In the 1-9 year old children in the
former being 1.6 times higher (prevalence of Infection 10.9 and 7.6% respectively)16.
1.5.
Other Studies: In the study conducted in the tribal area in Madhya Pradesh 30, the tribal
population had a significantly higher prevalence rate of bacteriologically positive cases (15.0 per
thousand) compared to the non-tribal residents of the same area (9.7 per thousand). This was the
nearest approximation to a study of the bacillary case rates by economic stratification, as one
could have, without consciously designing for It, provided the hypothesis is true that the tribals
were economically weaker In the area than the non-tribals. In the isolated Andaman Nicobar
islands territory, the prevalence of smear positive cases among the primitive tribal population of
Nicobar island, was found to be 4.1 per thousand, higher than that seen in CMC Vellore study
(Table 10) and NTI.LS (Table 13).
1.6.
Mortality: Apart from these studies, one could consider Rajnarain's finding57, that there was
a considerably higher annual tuberculosis mortality rate in children aged 1-4 years old in the
Choolai area in Madras city, dominated by slums (239 per 100,000), as compared to the rural
areas of BCG.TRIAL or in NTI.LS in Bangalore district (between 52-55 per 100,000).
2.
SPECIALLY DESIGNED BY SOCIO-ECONOMIC CRITERIA:
2.1.
Wardha Study: The survey carried out in Wardha district is the only tuberculosis prevalence
study, specifically designed to observe the socio-economic aspects of population, as related to
tuberculosis prevalence rate25. It gives information on various socio-economic strata, re: place of
residence (urban/ rural); type of dwelling house (kutcha/ pucca), education, occupation and
income strata. (Table 12 and Appendix Tables iii & Iv). Of all the socio-economic groups studied,
the highest prevalence rate was found to be among the urban female professionals (8.49 per
thousand) as shown in Appendix Table iv. The rural women service group (5.20 per thousand) and
women cultivators (6.80 per thousand) were also particularly vulnerable.
Other salient features of the study are summarised as under:
2.1.1. By Age and sex: The prevalence in males was higher than In females (2.39 vs. 1.32 per
thousand population), both In urban and rural areas (Not on Table).
In rural areas, the prevalence was higher than In urban areas. The males had twice the
prevalence than among females.
The age group 55-59 and 60+ years had the highest prevalence, rising with age in males. In
females the rise was upto 39 years, falling after the age of 50-55 years.
2.1.2. By Literacy standard: The tuberculosis prevalence per thousand population was the highest
among the Illiterates (2.49) and lowest among the graduates (0.74) (Table 12). However In the rural
population, the high school group (1.79) had higher prevalence than those educated only upto
primary level (1.42). This has been Interpreted to be due to the hardship that a rural student has
to go through, leaving rural environs in pursuit of higher education.
For calculation of the respective prevalence rates by education levels, the eligible population
group in the denominator were considered (Narang P, Personal Communication).
2.1.3. By employment: Prevalence per thousand (Table 12) was the highest among the
professionals (including the petty shop keepers) (4.08) followed by cultivators (3.12) and
agricultural labour (2.45). The housewives had a comparatively low prevalence rate, but had
15
contributed a high proportion to the total prevalence of cases, owing to the group-size being
relatively larger. Of all cases In both sexes, about 70% were among those either classified as
non-worker (24.9%), cultivators (24.8%) or agricultural labour (21.4%). All these could be persons
without a regular source of income. Of the total cases in females, about 48% was among those
unemployed (called "non-worker" which included housewives), followed by agricultural labour
23.9% and cultivators 15.2% (Not on Table).
2.1.4. By income-group: The prevalence of pulmonary tuberculosis showed inverse relationship
with increase in per capita income from 2.04 per thousand in <Rs.lOO group to 1.09 in ), Rs.300
group (Table 12). The inverse relationship had held good both for urban and rural population
(Appendix Table iv).
In urban areas, prevalence in ), Rs.300 group was fairly high (2.18 per thousand).
The grouping by income, used in the survey was decided after a preliminary socio-economic study
in the rural areas of Wardha. The economic scenario, reflected by per capita income, is different
from India as a whole and gives a grim picture (Narang P, Personal Communication).
2.1.5. By area and living standard: The prevalence (2.4 per thousand) as found in those living in
"Kutcha" houses In urban areas was the highest. In rural areas, there was no difference In rates
between "Kutcha" - "Pucca" houses (Appendix Table Hi). It was probably due to small number of
pucca houses and also to the almost similar quality of life and the level of health consciousness
among rural population, affluent or otherwise.
3.
TUBERCULOSIS AMONG THE WORK FORCE
Dholakia53 contends that the proportion of workers among the tuberculosis cases is likely to be
more than among total population. This may have more to do with the distribution by age-sex in
the population than anything else, l.e., more among males than in females and among adults
than in children. Evidence, according to him, is lacking to assume a differential prevalence of
tuberculosis among workers and non-workers. His estimate of workers with tuberculosis in the
base-year 1993-94, among population aged 15 years and over is presented in Table 18. Of the
workers estimated to have tuberculosis In India, about 52% were in the age group 15-44 years. In
this age group, about 40% of the workers with tuberculosis were estimated to be women in the
urban areas. The proportion, however, was only 17.9% in rural areas. There was much lower
proportion of women among workers with tuberculosis in higher ages, especially in urban areas.
16
u
1.
V> DISCUSSION
SUMMARY OF TUBERCULOSIS PROBLEM:
The average rates of tuberculous morbidity and mortality, hypothetically considered to be relevant
to the country as a whole, are utilised to estimate the problem in absolute numbers, so as to serve
as a guide for planning for resources at the national level (Table 19). However, it is recommended
that the estimates be considered in the light of the comments made in para 2 (vide infra).
A brief interpretation of the epidemiological situation in India, along with the use of the
epidemiology in designing the tuberculosis programme in India (NTP) is given In Appendix (vi-).
2.
RELIABILITY OF DATA AND PROBLEM OF EXTRAPOLATION:
2.1.
Problem in Sampling and identification of strata: The near continental dimension of India
and the variability in the socio-economic situation from area to area and even within as small an
area as a district, raises the question of representativeness of the data and the wisdom of
extrapolation of the findings obtained from epidemiological studies carried out in limited areas to
other areas or groups. While some of the surveys had taken samples for ensuring a degree of
representativeness, others had arbitrarily selected the population. Even in the sample surveys,
owing to lack of hypothesis, an appropriate stratification by relevant variables could not be
carried out, thereby rendering the study population less representative for the area, to that extent.
Examples of both NSS and Tumkur surveys could be cited in this respect8'10. No doubt suggestions
were available from the results of these studies that the prevalence rates could vary by the
socio-economic strata in society, yet the information could not be reliable for lack of
representativeness of samples. The data from the Wardha study25 as well as Dholakia's study53,
however, could now be useful in this regard. Hypothesis on socio-economic aspects, gender
differentials and areawise distributions of cases besides the pressing problem of tuberculosis
among the workforce could now be formulated for designing representative sample surveys in
other areas of the country, apart form putting it to use in programme planning. Priorities may have
to be redefined, keeping in view the relatively deprived sections of the society. It appears that
tribal or urban slum dwelling population groups, living on the fringes of the society, could need
specially monitored programme, may be on the lines of that followed in the Nicobar or North
Arcot tribal population groups28,29'45. The higher prevalence in the urban slums, as observed in the
NSS, needs to be viewed now in the light of the projection that the proportion of urban slum
dwellers, already high at about 37%, is likely to escalate, to be about 50%, by the turn of the
century.
2.2.
Reconsideration on average prevalence rates: The review has highlighted the need for
re-consideration of the average prevalence rates for the country.
2.2.1. Infection: The question of considering the infection rate in the country to be 60-70%, in both
sexes of all ages needs to be reviewed. Given the inappropriateness of tuberculin testing for
discriminating the population as Infected and uninfected in the age group beyond 10 years (or
say 15+ years) in age, makes the estimates on Infection rates beyond this age inaccurate. From
Figure 2 it could be seen that the proportion of positive reactors to tuberculin could be a
phenomenon related to age. In the age group of 15-24 years, 93% of those who were negative
reactors to 1 TU, were still positive reactors to a higher dose, i.e., its only a small proportion who
would be negative reactors to any dose of tuberculin. Because of this problem, the estimates of
infection could only be made in younger age group, with any degree of accuracy.
17
2.2.2. Radiological cases: The revised estimates of radiologically positive bacteriologically
negative tuberculosis prevalence as per NSS are presented in Table 8 along with their revised
estimates, correcting them as suggested on JPR40 (see section III.C.V.). As per the corrected rates,
the bacteriologically negative but radiologically positive cases prevalence in the community
would vary from 2.6 to 4.7 (say, 3.0 per 1000, as average), instead of 10.3 to 18.6 (say, 16 per 1000)
without correction (Table 8).
2.2.3. Bacteriologically positive cases: The above information, taken together with the finding,
that the estimate of bacteriological case rate (culture positive) should be corrected to be 39%
more than the rate obtained from surveys examining only two specimens of sputum37, would mean
that the proportion between bacteriologically positive cases and radiologically active and
bacteriologically negative cases should be revised. The bacteriologically positive case rate in the
NSS, taken to be between 2 and 8 per thousand (say, 4.0 on an average) varying from area to
area, should be corrected to be approximately between 3 and 11 per thousand (say, 6.0). The
ratio between bacillary cases and radiologically active bacteriologically negative cases would
then no longer be 1:4 (i.e., 4.0 vs 16.0 per 1000) as currently estimated for India, but as 2:1 (i.e, 6.0
vs 3.0 per thousand on an average). The use of the revised rates (given in bracket in Table 19),
in preference to the oft-quoted NSS rates hitherto followed in respect of radiologically positive
cases in the community, has over-riding implications for the planning process of NTP as well as in
respect of resources-management under it.
2.2.4.
Current estimates on pulmonary tubercusis:
2.2.4.I. Estimates for Andhra Pradesh, South India: In a recent report, the prevalence rates of
bacteriologically as well as total problem of positive tuberculosis in Andhra Pradesh is estimated,
based on two studies of comparatively recent vintage, rural area in Medak (1992) and tribal area
in Khammam (1982)60 The smear positive prevalence among those aged 15 years and over in the
former was 1.62 per thousand. It was 5.13 in the latter. The coverage of sputum exam of eligibles
in Medhak study was only 70.8% and radiolograpic coverage, a mere 55%. To what extent the
rates obtained from low coverage of population could be taken to be representative is
questionable15. In most studies presented in the current review, the coverages were of the order
of 90% or more7,10'12'1415.
In the Andhra Pradesh estimate, presented by Ramana, the above rates were adjusted (Total
prevalence in the state 890 per 1000 in 15+ age), using the correction factors for varying methods
of screening and sputum tests, based on unpublished data from North Arcot study (TRC,
unpublished)61. This was to make the estimates comparable to NSS, NTI.LS and BCG Trial data7'1015
However, whether these correction factors were seeking to correct rates, falling within 95%
confidence limit, as was done in an earlier study62-63, could not be ascertained, owing to
unpublished and brief nature of the material under reference61. Correction factors for prevalence
rates based on statistically discriminated rates were provided in a later NTI study, revising the
earlier correction factors2462. The adjusted rates provided in Ramanna's report are recalculated,
adjusting for age-difference, screening method and bacteriological specimens examined'.
Accordingly, the prevalence rates for culture positive cases are found to be 300.0 per 100,000 for
5+ age group in Andhra Pradesh (270.0 to 330.0 per 100,000). These are similar to rates found in
NSS7. The prevalence of smear positive cases could be 130, 370 and 150 for Medak, Khammam
and Andhra Pradesh respectively, for the population aged 5+.
2.2.4.2. Estimate on patients on treatment: Based on data from secondary sources, as well as
qualitative study in 26 villages spread over 13 selected states in India, the National Council of
Applied Economic Research New Delhi has estimated the point prevalence of tuberculosis (all
forms) to be 4.23 per thousand, with an estimated total number of 3.8 million tuberculosis patients
on treatment in the country64. Since information on method, population, coverage and diagnostic
criteria are not readily available in the report, (as already discussed in Section IIIC, these have vital
18
bearing on the results), the above should be viewed more as an estimate of the load on the
health services than epidemiological estimate of the problem in the population at large.
2.2.4.3. Estimate on morbidity and mortality from SEARO workshop 1996: In the workshop on
country-specific estimates of tuberculosis morbidity and mortality, organised by the WHO SEARO
at New Delhi in November '96, all available country-specific data were used to estimate the
problem, by using four models, namely Notification Method, ARI Method, Incidence Study Method
and Triangulation Method (DISMOD). The current estimate on mortality for India, as arrived at, is
shown in bracket in Table 19. The disease rates are being further developed and not presently
included herein.
2.2.4.4. Use of estimates: The average rates, as estimated and presented above, could be of great
use in the planning for provision and utilisation of resources, as well as for monitoring of
programme output in terms of the problem in the population at large. It should be realised,
however, that these estimates, owing to the nature of their computation and large range, could
be of limited purpose in effect-evaluation of intervention. This is especially so, since in tuberculosis
control, one is called upon to discriminate between low initial prevalence rates with small amount
of change consequent on intervention (say between 5-7%) (see para 3.1, intra).
3.
CHANGES IN TUBERCULOSIS WITH TIME: ITS MEASUREMENT:
3.1
Indices for measurement: Starting from the NSS in 1955-58, several surveys were conducted
in different areas in India at different times (Table 1). It was observed that the comparatively low
prevalence rate of cases between 2-8 per thousand, (say, 4 per thousand) had more or less,
remained unchanged over the years. The reason for this is clear from an understanding of the
natural dynamics of tuberculosis (Figure 14). It could be observed that the pool of cases remained
unchanged over short period of time, without active intervention. On account of the relatively low
initial case prevalence rates (Table 9 and 10) and the expectation of a very small change in it,
if at all, the population sample size had to be considerably large to identify a statistically valid
change (Appendix Table ii )46,48. Even mortality rates in tuberculosis did not present itself to be a
sensitive index of actual epidemiological time trend. However, on interpreting the above survey
results on infection and disease by areas, especially their distribution by age and sex as well as
over time, Indian epidemiologists had taken the viewpoint that the disease could be in an
endemic phase in India, on a slow declining trend,taking their cue from Grigg's work58,59 (see Fig. 15
for the hypothetical secular epidemic curve).
It is to be noted in this connection, that the wide gap between mortality rate, case rate and
infection rate in the community (90:400:38,000 per 100,000 respectively) is also considered
significant with respect to the interpretation of the interpretation of the age of the epidemic in
India (Fig. 15). While dwelling on the current epidemiological situation in India, one may not miss
the rather disturbing recent findings on drug resistance as shown in Table 14, even though
information on this is still meagre.
3.2
A.R.I.: It needs to be recognised that bacteriological case-prevalence, in being the pool
of cases leftover and carried over time, is more of an index of a failure of the anti-tuberculosis
effort, than a representation of the secular epidemiological trend as such. Incidence of cases, on
the other hand, represent the current risk of developing disease among the previously infected,
and therefore give a cumulated risk over a long time, as it has to be observed in higher ages. As
distinct from these, risk of infection is the index, which represents the direct and a near-immediate
consequence of the presence of bacteriological cases in the community. Following extensive work
on the epidemiology of tuberculosis in the western countries in the comparatively recent times,
ARI has been recognised to reflect the current epidemiological situation in an area, in preference
to the disease rates34. It is also possible to derive from it an estimate of the current rate of
incidence of the infections cases, as suggested by Styblo49, also shown in Table 4. In the Bangalore
19
rural area studied by NTI in a 23 year period, ARI was seen to have declined at 2.3% per year
(Figure 3). The smear positive case incidence was 23 per 100,000 at the last survey, as estimated
from the prevalence rate of cases in 1984. It could thus be interpreted as coming down during
the period at a rate nearly corresponding to the fall in ARI. However, there was no other evidence
of ARI declining in India, apart from Kashmir valley (Fig 16). Thus, India could be identified as a
country of high transmission and inadequate decline, a situation which it shares with the
sub-Saharan countries (ARI 1-2.5%, annual decline 0-37o).
4.
CONTROL PROGRAMME AND EFFECT-EVALUATION:
Objective of a tuberculosis programme in the Indian context: One may wonder whether
4.1
the epidemiologists are not over-zealous in expecting a control programme, like it is in India with
a current efficiency at 33% or less, to bring in the epidemiological returns in a relatively short time.
For countries like India, with the likely current average annual number of smear positive incidence
of 750 cases in an average Indian district of 1.5 million population, the task of reducing it is
altogether a different proposition, as compared to, say, a country like the Netherlands, with an
incidence level of 12-15 smear positive cases in a million population (Table 20)47,65.
The Indian situation should be viewed in the light of the fact that already diagnosed cases
continue to constitute a major proportion of the prevalence (2/3rd) year after year (Fig.14) i.e., it
could be a sort "of an epidemic of the left-overs".51 This needs to be transformed through the
operation of a highly efficient treatment programme, as experts globally contend, with a
well-thought out case-finding network in place.
Some salient features of the epidemiological situation, as used for planning a relevant control
programme for the country, together with their interpretation with regard to the trend, is given in
Appendix Table vi.
4.2
Continued surveillance through ARI and effect-evaluation: In view of the large population
size required (Appendix Table ii) for obtaining information on disease from the repeat surveys to
be meaningful towards reviewing of the epidemiological situation from time to time, or effecting
a comparison from area to area following a tuberculosis programme, the alternative of carrying
out infection surveysjnstead, could be considered. For this purpose, sub-district level samples of
unvaccinafed children could be selected (cluster samples). Care should be taken to obtain
socio-economic stratification, in view of differences in rates as seen even between contiguous
areas. Study by Bleiker and unpublished information developed in association with the WHO
Geneva and available with the reviewer, shows that the relevant sample sizes required for
ARI-study in the population, could, infact, be a manageable activity66. The question of an
adequate number of unvaccinated children available in the community was not found to be a
problem, even if the proportion vaccinated was found to be as high as 80-90%67. It was also shown
that the exclusion of variable proportions of vaccinated children from infection surveys would not
affect the estimate68. Moreover, ordinary general health workers with simple training could carry
out the field work19,31. The finding from the NTI as well as BCG.Trial that the prevalence of various
grades of protein energy malnutrition among younger children had not influenced the estimates
of the prevalence of tuberculous infection, could be of special significance, in this context, to the
developing countries626364.
It is placed on record here that a study on ARI as related to some well-known health indices in the
community (e.g., child mortality, infant mortality and tuberculosis case fatality rates etc.) was
completed at the NTI Bangalore in 1993-94. (NTI, peri-urban follow up). When analysed, it could
show the way towards developing the ARI as an index for general health as well, besides for
tuberculosis.
20
S'
4.3
Epidemetric Models: Over and above the direct measurement of the situation through ARI,
it Is also suggested that repeat surveys In some areas be carried out in order to provide inputs for
construction of epidemiological models, feeding into them the data on operational efficiency of
the programme also as a variable, as done by the present reviewer's group48. The trend obtained
from such a model (Fig. 17) had shown a marginal decline, relevant to the current programme
efficiency over a period of 50 years or more, the decline almost getting arrested thereafter
corroborating the observation of epidemiologists on a slow decline5969. It is suggested that the
exercise of mathematical approximation could be perfected from the data obtained from
longitudinal surveys in selected areas, of course with adequate provision for reflecting socio
economic changes with time.
21
(
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26
I 1ST OF FIGURES )
F.l
Distribution of indurations to tuberculin test
01
F.2
Proportions of persons infected with M.tuberculosis and
other mycobacteria in a south Indian rural area
01
Estimated ARI and observed annual incidence of infection
over time
02
F.4
Tuberculous infection in Tumkur district by age and sex
02
F.5
Active and probably active tuberculosis as well as bacillary
cases in Delhi zone of NSS
03
Distribution of prevalence by population proportion in various
ages
03
F.7
Prevalence of cases of age, sex and method of diagnosis
04
F.8
Age-wise proportional distribution of prevalence cases in an
area with time
05
F.9
Drug resistance (INH) in tuberculosis cases in the community
05
F.10
Incidence of bacteriologically positive cases in a community
over a period of 5 years of observation.
06
Average incidence of bacteriologically positive cases by
tuberculin test induration size.
06
Epidemiological groups in population and incidence of
tuberculosis.
07
Prognosis of bacteriologically positive cases detected in a
survey over time.
07
Natural dynamics of tuberculosis in a community over a short
span of time.
08
Development of the wave of tuberculosis epidemic through
time.
08
F.16
ARI across India
09
F.17
Mathematical model showing hypothetical trend in
tuberculosis for a 50 years period.
09
F.3
F.6
F.ll
F.12
F.13
F.14
F.15
Fig. 1. DIS I RIBUI ION OF TUBERCULIN INDURATIONS
IN A POPULATION AGED 0-9 YRS.
—
AGE 0-14
% 96.4
20 -
N = 3950
A
h
15-
2.0
I
10 T3
C3
<u
iUL_
5-
3
0
C
AGE 5-9
3
% .85.3
20-
u
I
15-
105-
N = 3890
— 8.3
il
OV
0
r
5
20
15
10
25
30
35+
Indurations in nun.
'A' - Anlimode of distributions : Arrow to its right infected proportion
SOURCE : OLAKOWSKl”
Fig. 2. PROPOR J IONS OF PERSONS INFECTED WITH M. TUBERCULOSIS*
AND THOSE SHOWING NON - SPECIFIC SENSITIVTY** IN A RURAL POPULATION
mv
1OO
00
w
80
O
<
70
80
Id
BO
u
tr
id
a
’J dj
40
30
30
'4 5|
10
O
•----- 0-4 ---------1
------ 9-9 ---------
a a e
’ TV NEGATIVE
REALTORS
( O-D mmJ
’ TU POSITIVE
tWj REAC TORS
( IO mm
or mort )
10 - 14----- ,
I N
’5 - 24
O - 34
YEARS
JT7J2O TU NEGATIVE
HEAC Tons
(O-7 mm )
20 W POSITIVE
Hull REACTORS
I 8 mm or /nore |
A
* Infected - Persons who are I 1 U positive reactors
** Non - Spccfic sensitvity - Persons 20 TU positive reactors
among those with negative reactions to I TU.
SOURCE : CIIAKRABORTY el a!
I
32
Fig. 3. ANNUAL ESTIMATES OF RISK OF INFECTION (1962 - 1985) AND OBSERVED ANNUAL
INCIDENCE OF INFECTION (1962 - 1967)
I
5
I
O
ESTIMATED ANNUAL
Id
O
RISK RATE (t)
--• OBSERVED ANNUAL
INCIDENCE OF INFECTION (•fe);
<
Z
UJ
O
(T
UJ
0.
5
O
O- 1
-
O-OI - 1—r~i—r
m
in
io to <n
o> o> cn , co
in
co
OT
•— »— •—
z
sz
< S5 §—»
S. o S.
D
TIME OF SURVEY
SOURCE : CHAKRABORTY, AK el al
13
Fig. 4. PERCENTAGE OF REACTORS BY AGE AND SEX
(TUMKUR DIST. 1960)
•o
-------- MAK
..........UMAlt
TO
g<°
«
r
g 40
u
J.o
X?
u
0
J
«o
TO
M
X1
H
Reactor : 10mm and over
<0 45
50
55
IQ
SOURCE : RAJNARAIN el al
8
FIG. 5. PREVALENCE OF DISEASE IN DELHI ZONE BY AGE & SEX
A . ACTIVE & PROBABLY ACTIVE CASES ON MMR
DELHI
^towns
CITY
5-
VILLAGES
I
----- /
AGE
AGE
AGE
B. BACTERIOLOGICALLY POSITIVE CASES.
I• ..................................
DELHI
o t.r
villages
TOWNS
0
0
I
I
MALES
FEMALES
SOURCE : NSS (7)
FIG 6
DISTRIBUTION OF AGE WISE PREVALENCE
OF BACILLARY CASES IN THE COUMMUNITY
POPULATION
AGE GROUP
AGE GROUP
40
50%
20 +
50%
0-!9 7%
k93%
TB CASES IN THE POPULATION
Source: Author (Unpublished)
Fig. 7. PREVALENCE OF DISEASE BY AGE SEX
AND METHOD OF DIAGNOSIS
2000
J2OO
ao o
oo
o
200 O
Ao o
o
22 0 O
O O
OO
O O O-
■4BOO
240
/ 2 oo —
o
-------- |F—'1-------- |------- "T
o» ■
o
ti
O)
vt
'*■
'
i
O
o>
j
i
o»
»
x-
1“
o»
J
T T O7 *O7 77TT777'?-*7 O
7 T‘O O *c> O W) o
O
k<->
AGE
GROUP
{YEARS)
Categories of eases :
a) Culture Pos. on 2 specimens
b) Culture Pos. on one specimen only
c) Culture Neg. smear Pos. ( 3 or more AFB)
d) Abacillary MMR - active (by 2 readers)
SOURCE : BCG. TRIAL?
Fig. 8. AGE-WISE PROPORTIONAL DISTRIBUTION
OF CASES IN BANGALORE RURAL AREA WITH TIME
(1981 -84)
100 -1
* 2
AGt G»OUP
40 -
5 • 19 *K5
60 -
Illi ,G‘J9 yPS
I m
| 3 5A.
10-
40 , YRS
S -29 YRS
Jliiiil—J
1961
1992
5
58%
21%^^ —
? i
21%
1961-63
H
1977
1994
4<)%
' 24
27%
1984-K6
SOURCE:CHAKRABORTY AK
47
Fig. 9. INCIDENCE AND PREVALENCE OF INH-RESIS PANT TUBERCULOSIS CASES
DURING 5 YEARS OF OBSERVATION (1961 - 68)
IN BANGALORE RURAL AREA
NEWLY DETECTED CASES
'V
CD
GJ
Cl
PREVALENCE CASES
-----...... —' 120
24
117.0
22 -
(24)
Tri.c- no S
(19)
O
§
o
20 -
19.0(11)
Cj
16 -
<n
10-
50
□Z
z:
o
G)
O
C
CD
c
60
/65.0(17)
C
58.0
(30)
.•
50
o’
Ul
46.0(11)
8 -
?6(1(j) • . ..
6-
4 -
7.0
(4-9).
40
Ferna Ies
o. • • o
Both Sexes
30
o
20
4^(4)
<D
2C
Z
o. —> -o
35.0(6)
GJ
C
Ma 1 es
GJ
10
14.0(6)
2-
o
3
(18(
(D
4/1
GJ
12.0(10)
10-
4/1
60
70 £
, •%6.0
12.0(21)
l/>
l/l
/92.0(27)- • ..o
85.0
76.0
(13)
14 -
12 -
90
’ • •
(22)
15.0(11)1
o
CO
O
Vi
97.0
(18)
IB -
O
Q>
- 100
GJ
CL
<D
o
120
n:
GJ
0
0
1-2
2-3
3-4
SURVEY 1-1961
SURVEY 4- 1966
0
1
7
3
4
SOURCE : OLAKOWSKI.T ii
(UNPUBLISHED)
(Percentage INH resistant out of total caes, in bracket)
Fig 10. INCIDENCE OF TUBERCULOSIS BY AGE AND SEX DURING
5. YEARS OF OBSERVATION
S
700 --------
*L--------------
600
\
—A—
/
g
Males
Females
o
o
o
Both Sexes
\
~r~
500
\
g.
/ 5V+
y
K______
400
\—————7-
o
/
X
/
------------ V—---------\ /
\
u
a
300
o
I
V
(D
35-54
200
u
All Ayes
l(iu —
o
15-34
0-0—o---- o —o---
0 L_J-----
-O—O—r
P~~°—< —O —0 — 0 —O—O
fir iv Mi-------
1MI1.
iU-lV
S (J R V°E Y t
Legend : Age in Yrs.
5-14
15-34
35-54
55+
All ages
n-iTi
iii-iv (-11
ii-Hr-
l-II
5-14
o-^ < —o — O—O — 0 — (
SOURCE : OLAKOWSKI T (11)
(Unpublished)
O—O —rO
Fig 11. AVERAGAE INCIDENCE OF TUBERCULOSIS BY SEX
AND AGE AMONG PREVIOUSLY NON- INFECTED AND INFECTED PERSONS
FEMALES
MALES
•
BOTH SEXES
800
o
o
o
-
700 -
— Tuberculin positive .....
Tuberculin negative
/
......Total
600 -
- 700
- 600
500 -
- 500
3
5
o
<u
£
400 -
- 400
300 -
- 300
V
------o
- 200
•S3
- /Oil
5-14
15-34
35-54
55 5-14
15-34
35-54
AGE GROUPS
55
5-14
15-34
35-54
u
0
55
SOURCE: OLAKOWSKI T,
UNPUBLISHED (11)
Fig. 12. INCIDENCE OF SPUTUM POSITIVE TUBERCULOSIS IN DIFFERENT
EPIDEMIOLOGICAL GROUPS
EPIDEMIOLOGICAL
SIZE
GROUPS
INCIDENCE OF CASES Ifrl THEM
AND ANNUAL
PROPORTIONAL
CONTRIBUTION TO
INCIDENCE FROM
EACH
7 3 K.,GROUP (’/.)
ANNUAL
INCIDENCE
RATES (>
OF EPIDEMIOLOGICAL
GROUPS (•/,)
30-4
J 6«B3
IB
X
1
TUB.
POS.
I
•6|
21 • 5
63-1
IL' 3C/
^kJj.O_
\ 5-2
0-5
CO 4
J, 6 -76 )
POPULATION
X-ray normals,
*
TUB.
NEG.
23-7
>r o -4i
Bocillory
TUBERCULIN
n[MBab (|cd L122
NEGATIVE
3-7
2-2
i7- e
H
/V :
76-3
'O
-f I -03
24.4
T USERCULIN
POSITIVE
Coses
n ETnnn ab nn] c p nrni
AB : inactive tuberculous lesion and non-tuberculous shadows.
CD : Probably active tuberculous shadows.
SOURCE : Gothietal50
Fig. 13. PROGNOSIS OF TUBERCULOSIS CASES DURING 5 YEARS
OF OBSERVATION, ALL AGES AND BOTH SEXES.
:•j 6-3
rnrnrnjFo^ nW® jjTTPr
10-3
27-6
95
135 32-5%
lilL. f
= I
---- >5 1
= l2i7
I
I
I26c
IOO7<
1
SI
-TTMimnn
i
I
f
//3\/A /VxA-r
30-1
T0
10 2 %
421 < > J.V/.? ?zi
-
— 1-5
1-5
15
I
4 •5
49 3 %
III
WH-I
-2 —
3
5
Non-infected
Radiological ly liunnaI
CD Shadows
Infected
Radiological ly ilonual
Bacteriologically
Pus i tive
AB Siudows
Deaths
SOURCE : OLAKOWSKI T, UNPUBLISHED
II
11G 14
POOL OF TUBERCULOSIS CASES IN THE COMMUNITY
(NATURAL DYNAMICS)
POPULATION
ADDITIONS TO
POOL OF CASES
AT 0.13% OF POPN.
ANNUALLY
DEAD(d)
ELIMINATED
INClDENCE(i)
38 %
Z CURE(c)
1
/ 20% \
I
62%
62%
PREVALENCE CASE CONTINUING
62°/o (0.62)
CASE PREVALENCE
INITIALLY
-0.20
ptO 1.0
CASE PREVALENCE
ONE YEAR
NEXT YEAR
ptl 1.0
-0.18 +0.38
(-d-c+i)
Source Author (Unpublished)
Fig. 15. DEVELOPMENT OF THE WAVE OF TUBERCULOSIS EPIDEMIC
THROUGH TIME
o
o
o
TUBERCULOSIS WAVES
1 000 -
INFECTION
800 -
DISEASE :
. .’
5
BOO
-
UJ
700
-
RURAL
80 0
- a
MORTALITY
a
u
LU
•n
o
5
p
yta.
URBAN
500
-
4 00
-/
j
w —
3 00 - ]/
2 00 - P
10 0 - r
I
50
I
100
-1000
* °
500
> O
£O £
I
i
i“
150 200 250 300
YEARS
(SEMI DIAORAMATIC - ADAPTED FROM
X
E R N. GRIOG )
SOURCE : CHAKRABORTY AK
47
The tuberculosis epidemic curve appears similar in form to those of other infectious
diseases. However, the former develops through centuries. It has an ascending limb (phase
of spread), a peak (phase of transition) and a descending limb (phase of decline), followed
by endemicity. The essential proximity of infection, disease and mortality curves
characterises the phase of spread (shown with arrow 'a'). Wide gaps between one and the
other rate develop at the peak and descending limb (shown with arrow ’b ). In India, gaps
similar to the latter, exist now. An inference that could be derived is obviously of an
advanced epidemic curve, probably in declining phase. The urban - rural epidemic curves
are different entities - but could cross at some point in the descending phase. The urban rural distribution presently observed in India, may be viewed in this light.
I
FIC 16. ANNUAL RISK OF INFI'CTION (ACROSS INDIA)
c.
V
ri s
o
r
s
/
r
7
K. VALLEY 1.4
ARI:
i DECLINE
_> STATIC
^2
o
)
KULU 1.8
HARYANA 1.5
J
/
RAJASTHAN
AGRA 1.8
}
(0-4)-(1.4)
,
c
--------)
-MBANGALORE
a 1.08 T
1.66 |
b 0.99 f
LOT |
.w>.c1 12-r
061 I
I
a c b
a"
MADRAS
\ 1.79 (STATIC)
I ►
(y) 2.23 i ►
/(x) 1.4
bangalore
i
S' ■
TIME OF SURVEY
a
RAJASTHAN
1972 & 1991 (Separate)
area
b) 1^4-79 r.
BANGALORE (a) 1966-73
(c) 1962-85
.
MADRAS
1969-1984
OTHERS - 1972
Scale 1:17.000.000 1cm = 170 kms
Lambert Conical Orthomorphic Projection
M'
I
I
SOURCE ; CAUTHEN (WHO)
HQ
Fig. 17. MODEL DEPICTING HYPOTHETICAL TIME-TREND
OF TUBERCULOSIS IN BANGALORE RURAL AREA.
0 40
0 39
Id
o
UJ
z
UJ
0-2C-
<
UJ
ex
a.
0 19 0 18-7
0
20
25
30
40
5b
YEARS
NO DISTRICT TUBERCULOSIS PROGRAMME ( DTP )
NO DTP < 0-5 YRS.) CF 33 T. SR 100 *4 (6- 50 YRS )
NO DTP(0-5 YRS.) CF AQ’4 SR 1007. ( 8-50 YRS )
CF-CASE FINDING
SR- STANDARD REG'MEN
10
SOURCE : CHAKRABORTY AK
47
(
SI.
No.
LIST OF TABLES
)
Particulars
Page No.
01.
Prominent epidemiological studies
01
02.
Prevalence of infection (Reagent RT-23)
04
03.
Prevalence of infection (Reagent PPD-S)
04
04.
Annual incidence of infection and smear positive case
incidence
04
05.
ARI (NTI.LS and BCG.Trial)
05
06.
ARI across the country
05
07.
Area-wise prevalence of pulmonary tuberculosis by sex
06
08.
Area-wise prevalence of radiologlcally positive
bacteriologically negative tuberculosis
07
Prevalence of bacteriologically positive cases
(M.M.R.-Screening)
08
Prevalence of bacteriologically positive cases
(Symptom-Screening)
08
11.
Prevalence of bacillary cases by age and sex
09
12.
Prevalence by selected socio-economic attributes
10
13.
Proportion smear positive in prevalence
11
14.
Proportion drug-resistance in different studies
11
15.
Incidence of tuberculosis cases
12
16.
Estimated annual tuberculosis mortality rates
12
17.
Tuberculosis prevalence and Incidence In paediatric
population
13
18.
Estimates of workers with tuberculosis of lungs In India
13
19.
Problem of tuberculosis in the country (on average)
14
20.
Indian situation set against advanced countries.
14
09.
10.
Table 1: PROMINENT EPIDEMIOLOGICAL STUDIES IN INDIA
REPORTED/UNREPORTED
Short Title
Refere
nee
Year
Area
Design
Examined popn & age
group
Method & investi- gations
Outcome
•Madanapalle
Town study
5
1948 -49
Madanapalle town
Arbitrarily
selected
Popn size
14,000
All ages-Tuberculin test
PPD-S
lTu-10 Tu-100 Tu MMR
Sputum Culture
i) Infection rate
ii) X-ray active case
rate
iii) Bacillary case rate
•Madanapalle
study (M.S.)
6
1950 -55
Madanapalle town
& rural area
Sample Survey
60,000
5+ in age
a) House to house census
b) All ages-tuberculin test, PPD-S, ITu-10 Tu-100
Tu; c)5+ age MMR Sputum Culture
-Do-
•National Sample
Survey(N.S.S.)
7
1955 -58
6 Zones:
Hyderabad
Madanapalle,
Patna, Trivan
drum, Delhi,
Calcutta. Towns,
villages & 1 city
in each zone
Sample Survey
representing 40%
of Indian popn
Cities-131,319
Town-59,548
Villages-137,271
5+ in age
a) House to house census
b) MMR 5+ in age
FROM MMR-abnormals:
c) Direct Smear of Sputum -2 Specimens
d) Two laryngeal swab culture
i) X-ray active case
ii) Culture positve
case
•Tumkur Study
8
1960 -61
Tumkur district
Sample Survey
About 30,000
10+ age
a) House to house census;
b)MMR 10+ age
c) Tuberculin testing all ITu RT 23
i) Infection
ii) Xray active case
iii) Culture+ case
•Tumkur
Resurvey
9
1972 -73
- Do -
- Do -
- Do -
-Do -
- Do -
•'Long'Survey
(LS.NTD Su 1
Survey 2
Survey 3
Survey 4
Survey 5
10,11
12
1961 -68
1961 -63
1962 -64
1964 -66
1966 -68
1977
3 sub-districts
(taluks) of
Bangalore dist
Sample Survey
Popn 66,000
Age 5+
a) House to house census
b)Tuberculin test to all
ITu RT 23
c) MMR-5+ age
-Do Fate of infected,
suspects, cases &
other risk-groups
Sub-Sample
Popn about 14,500
•LS:Followup
13, 14
1984 -86
Fresh Sample in 2
of the above 3
Taluks
Sample Survey
Popn. about 30,000 age 15+
Tuberculin 0-44 yrs ITu RT 23
Chest symptom questioning: 15+ yrs 2 specimens
culture & smear exam from chest symptomatics/
tuberculin reactors
Infection & case
rates
Table P.No.l
•BCG Trial
(BCG.TL)
15
1968
Followup every
214 for 71/z yrs
Chingleput district
Tamil Nadu
Selected for
study of BCG
efficacy
All ages(l+) Ap-prox
360,000 in 209 contiguous
villages and 1 town
a) House to house census
b) All ages tuberculin test PPD-S
c) MMR 10+ age, d)2 specimens of sputum from
MMR abnormals - direct smear & culture
a) Infection rate
b) Xray active cases
c) Bacillary cases
•BCG Trial
(Infection Trend)
16,17
1978
1983
-Do -
- Do -
Popn: 1-9 yr. 10 yr trend:
Survey 1, 8703 "15 yr
trend: Survey 1, 4808
Tuberculin test PPD-S
Annual infection rate
• BCG Trial
6 resurveys
18
1968 -83
-Do -
- Do -
As in BCG trial with
selected group for followup
MMR-5+ in follow up surveys
Incidence of cases
•Infection
surveillance
feasibility study
19
1983 -84
Anantpur dist AP
Dharmapuri dist in
TN
Arbitrary selected
population
Aged:0-9 yrs
Anantpur-4350 in 12 vils
Dharmapuri-2077 in 6 vils
Tuberculin testing by general health workers
ITu RT 23
Infection rate
•New Delhi study
6 surveys
20,21
1962 -75 (resu
rveys at 214 yr
intervals except
Su6: after 4yrs
from preceding)
New Delhi area
under New Delhi
TB centre
Population
covered by
Centre
Aged-5+
Approx 30,000
a) House to house census
b)MMR
c) MMR abnormals-culture of sputum & laryngeal
swab
d) Followup exam by xray, repeated sputum
Xray case, Bacillary
case rate
Prevalence &
incidence of cases
•All India
Tuberculin survey
23
1972
Villages in Kash
mir, Kulu, Lohaghat Pithoragarh,
Agra,Haryana,
Rajasthan
Selected for
altitude contrast
1-4 yrs Between 76-769
children in each
PPD-S, 5 Tu
a) Infection rate (ARI)
b)Non-specific
sensitivity
• Kashmir Survey
22
1978
Kashmir valley
Sample Survey
0-4 yrs popn 2448
Tuberculin testing PPD-S, 3Tu
Infection rate (ARI)
•Bangalore dist
study on nutrition
2 surveys
22
1974
1979
Dodballapur
subdist of
Bangalore
Sample survey:
repeated in same
villages
Aged 0-4 yrs
a) Tubeculin testing 1 Tu RT 23
b) Nutrition assessment
Infection rate by
nutrition grades
•Bangalore peri
urban study
24
1986 -89
Bangalore peri
urban area
Random Sample
of villages in a 5
km radius 19 km
from city centre
Aged 15+
56,000 persons
a) House to house census
b) Chest symptom screening
c) MMR
d)One specimen of sputum culture
from eligibles by (b)/(c)
Symptom screened
culture positive case
rate
- Do -
- do -
a) Aged 0-14
b) 01d cases of previous
survey
Tuberculin test 1 Tu RT 23
Infection rate (ARI)
Fate of cases
•Bangalore peri
urban repeat study
(under analysis)
Table P.No.2
•Wardha study
25
1981
Wardha dist in
Maharashtra
Central India
Purposive sample
(whole dist)
Aged 5+
Popn 773,500
a) House to house census
b) Socio-economic stratification
c) Chest symptom questioning
d) 2specimens of sputum from symptomatics culture & smear
Symptom-screened
culture positive case
rate
•Raichur
studyfAnalysis not
completed) by
TRC Madras
26
early eighties
Raichur dist in
Karnataka
Sample Survey
Aged 15+
Approx 70,000 in 56
villages and 21 town blocks
a) House to house census
b) Chest symptom questioning
c) 2 specimens of sputum from symptomatic culture & smear
- Do -
•Tribal study TRC
27
1980
Jawadhu hills of
N.Arcot dist in TN
Sample Survey
Aged 15 +
Tribal popn of 96,000 in 56
panchayats: 24 selected
a) Tuberculin test: 1-9 yr (N-6702) ITuRT 23
b)MMR 15+ age (N-12745)
c) Chest symptom questioning 15+ age (N-15075)
d)From symptomatics/MMR abnormals: 2
specimens of sputum-culture & smear
Culture positive case
rate
•Nicobar study
28,29
1986
Car Nicobar island
in Bay of Bengal
Entire island
Entire popn of 17,277
resident of 15 villages
a)Tuberculin test 0-14 (popn 5907) ITu RT 23
b) Chest symptom questioning 15+ age (popn 9514)
Infection rate, smear
positive case rate
•Madhya Pradesh
Tribal study by
Regional Health
office
30
1991
Morena dist in MP
Sample Survey
Aged 15+ Tuberculin test 19 yr (N-7642) Popn 23,000
in 37 villages
a) Tuberculin test ITu RT 23 - 1-9 yr age
b) Chest symptom questioning 15+ age
c) 2 sputum specimens by culture/smear for chest
symptomatics
Infection rate, smear
positive case rate
•Rajasthan study
by URMULin
Lunkaransar
31
1991 -93
Bikaner dist in
Rajasthan
Arbitrary selec
tion: 16 of 33 vil
in Lunka ransar
sub-dist
Popn 0-9 yr (N 2482)
Tuberculin test 1 Tu RT 23
ARI
..........................................................
NOTE: Other studies referred to in the text at respective places.
Table P.No.3
Table 2: PREVALENCE OF INFECTION IN DIFFERENT AREAS (with Tuberculin RT 23)
Study by:
Study Area
A) NTI
Age group (yrs):
B) LOCAL
HEALTH
STAFF/
TRAINING:
NTI
C) Local
hl th staff/
Time
Ref
Per cent infected*
0-4
5-9
10-14
0-9
0-14
1. Tumkur,"
1961
8
2.7
9.6
28.9
6.7
13.3
2. Bangalore,
1961
10
2.1
(1.8-2.4)
7.9
(7.3-8.5)
16.5
(15.7-17.4)
4.9
8.6
(8.3-9.0)
3. Bangalore
1984
13
1.2
(0.8-1.6)
5.3
(4.4-6.2)
9.2
(7.9-10.5)
5.4
(4.3-6.0)
1.Andaman & N
1986
28
3.7
12.0
19.6
10.0
2. A.P.(Andhra)
1983
19
9.7
3. Tamil Nadu,
1983
19
5.0-7.0
4. Rajasthan
Bikaner
1991
31
2.66
(1.54-3.78)
12.33
(9.98-14.68)
19.55
(16.44-22.66)
7.39
(6.08-8.70)
10.89
(9.58-12.20)
1-2
3-4
5-9
1-9
Age group (yrs):
Madhya Pradesh
1991
30
6.7(+1.8)
13.4(+2.8)
22.7(+1.7)
16.9
NOTE: •Infected: Those showing an induration jeyond antimode of its distribution; "Sample of whole district, urban & rural.
Others only rural. (Figures in bracket give range for 95% Confidence limit, wherever given in original paper)
Table 3: PREVALENCE OF TUBERCULOSIS INFECTIONS IN DIFFERENT AREAS BY AGE
(with PPDS)(Percentage showing tuberculosis infection)
Age Group(Yrs):- 1-4
5-9
10-14
15-19
20+
BCG.TR1AL 1979
4.9
14.9
30.4
48.1
74.4
Kashmir
1972
4.0
11.4
24.1
47.4
80.9
Kulu
1972
5.2
14.9
22.2
35.6
68.8
Lohaghat
1972
3.1
12.3
21.5
41.5
70.3
Pithoragarh
1972
4.1
13.2
31.1
49.4
71.4
Agra
1972
5.2
14.7
33.1
51.8
78.6
Haryana
1972
4.4
8.2
14.8
29.0
61.1
Rajasthan
1972
1.3
14.4
Source: Tuberculosis Prevention Trial08' and Rajnarain et alUir
NOTE: # Infected= Positve reactor to PPDS 12mm & over
33.8
45.1
77.1
Table 4: AVERAGE ANNUAL INCIDENCE OF TUBERCULOUS INFECTION AND
________ SMEAR POSITIVE CASE INCIDENCE (BETWEEN SURVEY 1 & 2)
Age
Annual Incidence of Infection %
0-4
0.8
5-9
1.07
0-14
1.0
1.63
All ages
Source: 1) NT1VIU’, 2) Olakowski et al(
Annual Incidence of Sm+ cases in ages 5+(per 100,000)
0.93
45
NOTE: Sm+=Smear Positive
Table P.No.4
Table 5: ANNUAL RISK OF INFECTION (ARI) ESTIMATED OVER A PERIOD IN
RURAL POPULATION GROUPS UNDER NTLLS13 & BCG.TRIAL16
BCG.TRIAL. Children aged 1-9 yrs(,6)
NTI LS:Children 0-14 yr age(,3)
Survey
Panchayat area
Mid-Point of
observation
ARI(%) on standard
Prevalence rateD
Year
1
Mar 1962
1.12
1969
2
Oct 1963
1.12
3
May 1965
0.99
4
Jun 1967
0.92
5
Nov 1977
0.80
Follow up
Jun 1985
0.61
Total
NOTE:
Group 2
All*
1.28
2.17
1.70
1979
1.48
2.41
1.93
1984
1.43
2.08
1.73
1969-84
1.40
2.23
1.79
Age(Yrs)
ARI
(%)
ARI
Group 1
Annual decrease 2.3% per year; * No change over time in ARI
Table 6: ANNUAL RISK OF INFECTION ACROSS THE COUNTRY
Year
Area represented
Antigen used
Procedure of
popn selection
Year Mid
point
1960-61
Tumkur dist in south India
RT23 ITu
S.Survey
1960.9
1972-73
- do -
- do -
- do -
1973.0
1974-75
Dodballapur in Bangalore dist
- do -
- do -
1974.8
1979
- do -
1978
Kashmir valley
1972
Villages in:
1.08
1.04
0-4
- do -
- do -
1979.5
PPD-S 3Tu
- do -
1978.7
0-4
0.92
PPD-S 5Tu
Selected
1972.8
1-4
1.4
Kulu Valley
- do -
- do -
- do -
- do -
1.8
Lohaghat
- do -
- do -
- do -
- do -
1.0
Pithoragarh
- do -
- do -
- do -
- do -
1.4
Agra
- do -
- do -
- do -
- do -
1.8
Haryana
- do -
- do -
- do-
- do -
1.5
Rajasthan
- do -
- do -
- do -
- do -
0.4
Rajasthan
ITu RT23
Selected
1992.0
0-9
1.44
Kashmir
1991-
1.66
0-4
0.99
Source: "Siddique et al l31), others: Cauthen et al (22)
Table P.No.5
10614
Table 7: PREVALENCE OF PULMONARY TUBERCULOSIS BY SEX ACROSS THE COUNTRY
Area
Male
Female
Total
Male
Female
Total
95%
confidence
limit**
Calcutta
City(Calcutta)
18.30
14.15
16.73
7.16
5.12
6.39
5.16-7.62
Delhi
City (Delhi)
24.46
15.61
20.56
4.99
2.88
4.06
3.23-4.89
Town
14.13
12.69
13.47
2.09
1.83
2.45
1.54-3.36
Villages
14.84
11.98
13.51
2.99
1.92
2.49
1.87-3.11
City (Hyderabad)
17.71
13.09
15.44
5.31
3.03
4.18
3.44-4.92
Towns
22.99
17.57
20.42
4.47
2.30
3.44
2.32-4.56
Villages
23.33
18.33
20.88
2.93
1.62
2.29
1.70-2.88
City (Bangalore)
21.55
17.79
19.75
2.33
2.48
2.40
1.64-3.16
Towns
31.43
16.72
24.35
11.69
4.29
8.13
6.58-9.68
Villages
21.71
10.67
16.39
8.46
3.57
6.11
5.02-7.20
City (Patna)
19.13
21.30
20.12
6.43
6.31
6.38
5.10-7.66
Towns
21.84
18.12
20.22
6.22
3.98
5.25
3.83-6.67
Villages
18.42
14.43
16.58
7.07
4.43
5.85
4.58-7.12
City(Trivandrum)
17.19
.15.53
16.31
3.70
2.30
2.96
2.14-3.78
Towns
21.89
20.51
21.21
3.69
2.70
3.20
1.93-4.47
Villages
16.41
12.86
14.64
3.68
1.49
2.59
2.08-3.10
BA cases*
Rad 'A' or probably 'A' case*/ 'BA' (+) & (-)
Zone
Hyderabad
Madanapalle
Patna
Trivandrum
Source: NSS0
Note: Rad- Radiologically; 'A'= Active; 'BA' = Bacteriologically; (+) = Positive; (-) = Negative;
* Rates per 1000 x-rayed in persons aged 5 years and over; ** Computed by author
Table P.No.6
Table 8: PREVALENCE OF RADIOLOGICALLY POSITIVE BACTERIOLOGICALLY
NEGATIVE TUBERCULOSIS ACROSS THE COUNTRY
Area
Zone
Population
x-rayed
Radiologically (+) Bacteriologically (-)
Estimated (#)
Rate/1000
Revised Rate/100044
Calcutta
City(Calcutta)
16,155
167
10.34
2.58
Delhi
City(Delhi)
22,780
376
16.50
4.13
Town
11,215
124
11.05
2.76
Villages
25,075
276
11.01
2.75
City(Hyderabad)
29,240
329
11.25
2.81
Towns
10,410
176
16.91
4.20
Villages
25,590
475
18.56
4.65
City(Bangalore)
15,986
277
17.32
4.31
Towns
12,955
210
16.21
4.01
Villages
19,622
202
10.29
2.55
City (Patna)
14,970
206
13.76
3.41
Towns
9,880
148
14.98
3.75
Villages
13,820
149
10.78
2.68
City(Trivandrum)
16,665
222
13.32
3.30
Towns
7^95
137
18.04
4.48
Villages
38,800
468
12.06
3.01
Hyderabad
Madanapalle
Patna
Trivandrum
Note: (+) = Positive; (-) = Negative; (#)No. estimated on the basis of population xrayed and the proportion
bacteriologically positive (given in Table 7); ♦♦Revised after making allowance for 75% over-estimate(40)
Source: Based on NSS™, derived on applying bacillary case rates to the corresponding population.
Table P.No.7
Table 9: PREVALENCE OF RADIOLOGICALLY ACTIVE AND BACTERIOLOGICALLY POSITIVE
TUBERCULOSIS FROM LIMITED AREA STUDIES (ON MMR-SCREENING)
'P' of disease (per 1000)
Year &
Reference
Study
'RAD' 'A' & 'BA' (-)
1. Madanapalle study (in aged 5+ yrs)
1950-55(6)
1. New Delhi(in aged 5+ yrs)Survey 1
Survey 3
Survey 6
1962(2I)
1967
1976-77
13.20
9.70
9.90
2. Tumkur(in aged 10+)
Survey 1
Survey 2
1960(8)
1972W
10.0*
11.6*
3. NTLLS(in aged 5+)
Survey 1
Survey 4
Survey 5
1961(,0)
1968(10)
1977(12)
(40)
10.5
4.BCG TRIAL (in aged 10+) Survey 1
Survey 3
Survey 5
Survey 7
1968(,5)
1973(,8)
1978(,8)
1983(,8)
14.30
5. NTI-Rural Study (in aged 5+ yrs)
1968(40,43,44)
4.0
4.64
4.1
4.232 (15.00b)
4.00
4.00
3.20
17.2
13.7
13.7
4.10®
4.40b
18.6(14.0*)
11.0(16.0*)
4.06(3.96<)
3.93(3.48 •)
4.92(3.58 •)
4.03
10.70(10.55>)
- (10.37B)
-(8.68<)
- (7.75b)
5.40
25.0
3.10
1986-89(24)
2.50
(27)
7. TRC.TRIBAL Area
6
4
3
2
6. NTI Peri-Urban (in aged 15+ yrs)
5
on 2 reader & on JPR
________________1______________
SPECIAL REPORT WITH JPR
'BA' (+)
Total 'A'
(with/with out
' BA' positivity
4.30
MOTE: ' P/=Prevalence; ' RAD'^Radiologically; ' BA/=Bacteriologicaliy; 'A/=Active; JPR=Joint Parallel Reading'407^
■RAD' A'=Clmically significant x-ray cases(6); 2When evaluated with all results; • Standardised prevalence
rates for comparability; (*)When x-rays of both surveys evaluated by the same set of readers for excluding
reader-variation^
Table 10: PREVALENCE OF BACTERIOLOGICALLY POSITIVE TUBERCULOSIS FROM VARIOUS
_______________ SURVEYS IN INDIA (WITH SYMPTOM-SCREENING AS A METHOD)
SI.
No.
Observed 'P7 per 1000
Study
Year
Cu+
01
LS FOLLOW UP(14)(Aged 10+ yrs)
1986
4.38
02
NTI PERI-URBAN(24)(in 15+ yrs age)
1986-89
1.8-2.3
03
WARDHA STUDY(25) (in 5+ yis age)
1982
1.73
04
CAR NICOBAR STUDY(28)
1986
05
RAICHUR STUDY(26)
06
M.P. TRIBAL STUDY(30)
07
Note:
Cu &/ Sm+
Sm+
1.9
4.1
3.3
1982
CMC VELLORE STUDY(45) (in 10+ yrs age)
1981
KP/= Prevalence; 'Prop'= Proportion; Cu+= Culture positive; Sm+= Smear positive;
* (Tribals 15.0, Non-Tribals 9.7)
10.9
12.7*
2.41
Table P.No.8
Table 11: PREVALENCE OF BACILLARY• CASES IN A COMMUNITY BY AGE AND SEX
Proportion of case contributed by population proponion
No. X-rayed
Age group (yrs)
10-14
15-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70+
All
Male
Female
Male(a)
Female0’’
19437
11272
10408
10607
9588
9017
7357
7253
5695
4657
3617
2455
2265
103629
17412
10170
11654
12505
10300
9576
7865
7134
5609
4434
2981
1964
1436
102980
0.36
I. 69
7.20
II.41
16.69
20.07
25.01
26.20
33.71
34.79
32.35
36.67
36.63
15.60
0.35
0.79
3.09
3.20
4.76
5.64
7.54
8.41
6.60
6.54
8.39
6.11
6.27
4.12
NOTE: •Culture Positive
Total Population - (both sexes all ages): 259,291. (10+ in age + 26.65% being Regd population in 0-9 years age)
Population(10+ yrs)
206609
Total cases(10+ yrs)
(both sexes)
2,041 (Prev 9.88, Adjusted 10.7 / 1000)
Total cases(10+ yrs)
(Males)
1,617 (Prev 15.60 / 1000)
Total cases(10+ yrs)
(Females)
424 (Prev 4.12/ 1000)
Source: BCG.TRIAL(,5)
Table P.No.9
Table 12: PREVALENCE OF TUBERCULOSIS AMONG POPULATIONS IN A CENTRAL
INDIAN DISTRICT (by selected socio-economic attributes)
Some selected
attributes
Popn aged 5+
Sex Ratio
Proportional
contribution to total
cases (%)
'P7 cases/ 1000
(urban & rural)
Sex-Ratio in ' P7 cases
(male /female)xl00
(urban & rural)
SOCIAL
PLACE OF RESIDENCE:
Kutclia houses
108
66.85
2.09
189
Scmi-pucca
109
25.64
1.73
175
Pucca houses
109
7.51
1.17
154
Nil
67
51.20
2.49
189
Primary
124
29.07
1.51
252
High School
171
18.53
1.55
212
Graduate/above
310
1.2
0.74
193
Hindus(Cat 'A')
109
45.21
1.76
170
Hindus(Cat 'B')
107
30.11
1.93
200
Neo-Budhists
109
16.61
2.00
189
Muslim
109
5.35
2.72
176
O tilers
105
2.72
1.55
151
EDUCATION:
RELIGION:
ECONOMIC
INCOME(in Rs./month/capita):
< 100
101
43.29
2.04
211
100-199
111
45.77
1.87
160
200-299
116
9.98
1.50
177
>300
175
0.96
1.09
Non-worker
34
24.92
1.74
170
Student
125
6.63
0.43
140
Professional
1219
4.39
4.08
105
Cultivator
245
24.84
3.12
157
Agri-Labour
85
21.41
2.45
194
O tliers
641
17.81
3.0
962
OCCUPATION:
IN ALL
108
See Appendix Tables iv & v.
Source: S. Nayar et al0^
1252(100.00)
1.87
& Total population aged 5 year and more : 687,401;
'P7 cases - Culture positive prevalence
181
Table P.No.10
Table 13: PROPORTION SMEAR-POSITIVE IN A GIVEN RURAL COMMUNITY (1961-19S4)
Inter
vention
Surveys
Time
Age
grp
Popu
lation
Case
(#)
Stdd case' F
(per 1000)
Smear
positive
number(*)
'P'
Sm+
cases (per
100000)
1
2
3
4
5
6
7
8
9
No organi
sed Inter
vention
'Long'
Survey 1
1961
5+
43889
178
420
83(47.0)
189
-do-2
5+
40633
151
416
71(47.0)
175
- do -3
5+
40405
136
412
61(44.8)
151
NTP 1970
- do -4
68-70
5+
41213
162
426
95(58.6)
• 230
Follow-up
Survey
1984
10+
21924
96
438
15(15.6)
68
NOTE: Stdd=Standardised; 'Long' = Longitudinal; 'P7 « Prevalence;
'Sm+ = Positive; (*)Per cent in bracket 8/6x100
Source: Chakraborty et al(14)
Table 14: PROPORTION OF PATIENTS WITH DRUG-RESISTANT BACILLI FROM
DIFFERENT STUDIES
[Bacillary Resistance to drugs (per cent)]
Year
INH
Survey 1
1961-63
11
Survey 2
1962-64
18
Survey 3
1964-66
27
Survey 4
1966-68
22
LS Followup(a)
1984-86
17.7
Bangalore Peri-urban(a)
1986-89
27.9
NEW DELHI STUDY-6 surveys00
1962-77
8.1
NDTBC area(c)
1992
18
0.6
Raichur StudyC6)
1980s
29.5
7.6
Survey
NTI.LS:(10)
RFP
To any
INH & RFP Combined
11
31.25
8.1
33.70
6.97
24.40
34.1
7.6
NOTE: (a) Author, unpublished information; (c) Jain NK, personal communication
Table P.No.ll
Table 15: INCIDENCE OF PULMONARY TUBERCULOSIS IN INDIA
Study
Period of
Study(yrs)
Urban/
Rural
Popn aged
in yrs
Annual Incidence Rate
Cu/1000
'M' alone/ 1000
As a '%' of 'F
A) Using MMR-Screening/Periodic Survey Method"
1. New Delhi Study (20)(2,)
1-2
1962-65
Urban
5+
0.90
44.4
2-3
1965-67
Urban
5+
1.30
30.8
3-4
1967-70
Urban
5+
1.10
36.4
4-5
1970-73
Urban
5+
0.60
35.0
5-6
1970-77
Urban
5+
1.80
15.6
Survey 1-2°
11961-62
Rural
5+
1.36
2-3
1962-64
Rural
5+
0.80
47.1
3-4
1964-68
Rural
5+
1.04
34.0
Survey 1-2
1968-71
Rural
15+
3.83
27.5
4-5
1976-78
Rural
15+
2.30
41.4
6-7
1981-83
Rural
15+
3.00
33.4
Survey
2. NTI.LS(10)
(a)(a)
30.8
3. BCG.TRIAL(,8)o
B) Direct Observation of Incidence
CMC-Vellore
81-83(45)
Rural
10+
1.10
46
Nicobar Study
1986(28)
Rural
15+
1.50
36
NOTE: 'Cu'=Culture; ' Popn'=Population; ' P/=Prevalence; ' NT=Microscopy; "Annual average incidence calculated
between two surveys; nRates on the basis of standardised population of survey 1 NTI.LS & BCG TL respectively;
’For NTI.LS diagnosis by culture (with/without microscopy): for others microscopy and /or culture;
<>)(,>Microscopy positive among cases (culture positive):!).65 per thousand.
Table 16: ESTIMATED ANNUAL TUBERCULOSIS MORTALITY RATES IN THE BANGALORE
RURAL AREA WITHOUT ACTIVE INTERVENTION OVER 5 YEARS
Age group
(yrs)
Rate between two consecutive surveys/100000 popn
Average ' %' mortality O
1-2
2-3
5-14
9.8
5.8
15-34
79.4
34.1
51.7
9.9
35-54
146.4
135.2
101.3
12.7
55+
394.1
324.3
580.3
9.8
Total
95.4
69.2
87.6
9.4
3-4
(1-4 survey)
1.6
Source: CHAKRABORTY AK(i2) NOTE: ODeath due to tuberculosis as proportion of total death (per cent)
Table P.No.12
Table 17: PREVALENCE AND INCIDENCE OF TUBERCULOUS DISEASE IN
PAEDIATRIC AGE GROUP (NTLLS)
Incidence( per 1000/ year)
'RAD' active, 'BA'(-)
No.
follow
ed up
Bacillary cases
' RAD' active ' BA'(-)
1.0
3.0
4833
0.2
0.3
3880
1.0
4.0
3860
0.4
0.7
8731
1.0
3.0
8693
0.2
0.5
Prevalence (per 1000)
Age
group
(yrs)
No.
X-ray
ed
Bacillary cases
5-9
4851
10-14
5-14
Source: Gotlii et al(54)
NOTE: 'RAD'=Radiologically; ' BA'=Bacteriologically
Table 18: ESTIMATES OF WORKERS WITH TB OF LUNGS IN INDIA 1993-94
(in '000)
Rural Areas
Age Group
Urban Aeas
Male
Female
Male
Female
(2)
(3)
(4)
(5)
15-44
661.3
143.865
189.337
125.818
45-59
385.613
95.016
97.325
7.271
60+
360.276
34.379
60.721
0.639
(1)
Source: Dholakia, 1996 (53)
Table P.No.13
Table 19: PROBLEM OF TUBERCULOSIS IN INDIA (AVERAGE)
(estimated on 1991 population)
1.
Population: 844 million: 726 million in 5+ age (85%)
2.
Prevalence of Infection
a) Rate - 38% (all ages)
3.
b) more than 50% in 40+ age
Prevalence of radiologically active abacillary pulmonary tuberculosis
a) Rate - 1.6% (0.3, 0.26 - 0.47%)
4.
b) Number - 12 million (2.3 million)
Prevalence of positive cases
a) Rate - 0.4% (0.6, 0.3 - 1.1%)
5.
b) Number - 3 million (4.4 million)
Prevalence of total cases
a) Rate - 2.0% (0.9, 0.56 - 1.57%)
b) Number - 15 million (6.5 million)
6.
New patients arising annually: 2.5 to 3 million
7.
New bacillary cases arising annually:
8.
Case fatality Rate: 14% in untreated bacillary cases
9.
Mortality (annual): a) Rate - 50 - 80/ 100,000 population (45,
28-71 per 100,000)*
a) Rate - 0.13%
b) Number - 1 million
b) Number - 0.3 - 0.5 millions (0.42, 0.26 0.67 millions)*
NOTE: Sec under Discussion V. 2.2. for an update.
( ) Rates in bracket based on Appendix Table v
Derived from
WHOSEARO workshop on country specific tuberculosis etstimate, 1996 (unpublished)
* Donv^
r™™ u/uncnADn
Table 20: INDIAN SITUATION SET AGAINST THAT IN THE EPIDEMIOLOGICALLY
ADVANCED COUNTRIES HEADING TOWARDS THE GOAL OF ELIMINATION'
Epidemiological Situation
Present
Country
Qualification for 'Close to Elimination' Status
Incidence of smear positive
cases per million/year
Prevalence of infec
tion all ages (%)
Most Ad
vanced*
12-15
15
India**
500(750)
40
Incidence of smear positive
cases per million/year
10
(1.2)
Prevalence of infec
tion all ages (%)
1.0
♦Norway, Netherlands, etc.: (ARI 0.1 to 0.01%, 10% Annual Decline, 'Close to Elimination Status' projected to be
achieved by 2025 A.D.)(65);
NOTE: **Figures based on NTI Survey (10); ()Calculated for 1.5 million population i.e., an average Indian district.
Table P.No.14
c
APPENDIX TABLES
I
Table No.
Heading
Page No.
i.
Prevalence of infection in Bangalore rural area
I
ii.
Population required for repeat surveys
I
iii.
Tuberculosis prevalence by some social
attributes
n
Tuberculosis prevalence by some economic
criteria
Ill
Suggested revision of average tuberculosis rates,
India
Ill
Uses of Epidemiology
IV
iv.
v.
VI.
APPENDIX Table (i): PREVALENCE RATES (%) OF INFECTION
(23 years period) (With Confidence Intervals of Estimate)
Mar '62
II(1.58)a
Oct '63
111(3.17)A
May '65
IV(5.25)A
Jun '67
V(15.67)A
Nov '77
Present0
(22.83)"
Jun '85
Rate
Range
2.1
(1.8-2.4)
1.8
(1.5-2.1)
1.3
(1.1-1.6)
(0.8-1.2)
1.5
(0.9-2.1)
1.5
(0.8-1.6)
5-9
Rate
Range
7.9
(7.3-8.5)
7.6
(7.0-8.2)
7.0
(6.4-7.6)
6.4
(5.8-7.0)
6.0
(4.4-7.6)
5.3
(4.4-6.2)
10-14
Rate
Range
16.5
(15.7-17.4)
16.9
(16.0-17.8)
16.1
(15.2-17.0)
15.4
(14.5-16.3)
12.1
(9.2-15.0
9.2
(8.0-10.5)
0-14
Rate
Range
8.6
(8.3-9.0)
8.6
(8.2-8.9)
7.7
(7.3-8.1)
7.1
(6.8-7.5)
4.7
(3.9-5.5)
4.8
(4.3-5.3)
0-14b
Rate
Range
8.6
(8.3-9.0)
8.5
(8.0-9.1)
7.9
(7.4-8.5)
7.4
(6.8-7.9)
6.4
(4.9-8.3)
5.4
(4.3-6.0)
Age
Survey
0-4
1(0)
(Estimated limits of infection rate at 95% confidence intervals in brackets).
a) Interval from I survey in years; b) Based on standardised population of I survey;
c) Decline in infection rates for each age group statistically significant over 22.8 years.
Source: Chakraborty et al(13)
APPENDIX Table ii*: POPULATION REQUIRED FOR REPEAT SURVEYS TO VALIDATE CASE
PREVALENCE RATES DERIVED FROM EPIDEMETRIC MODEL UNDER SOME INPUT VARIABLES
OF INTERVENTION
(Given Initial Case Prevalence Rate 0.389%)
(For Confidence Level 95%, One Sided Test, Power 80%)
Input Variables of Intervention
(b)
(a)
(c)
Year of
obser
vation
Case 'P'rate
estimate from
model (%)
Popn
required in a
survey for
validation
Case 'P'rate
estimate from
model (%)
Popn
required in a
survey for
validation
Case 'P'rate
estimate from
model (%)
Popn required
in a survey for
validation
10
0.312
89,748
0.281
43,609
0.281
43,609
25
0.286
48.302
0.239
21,194
0.238
20,881
50
0.255
27.232
0.190
11,104
0.175
9.354
Input Variable of Intervention: a) No intervention - 50 years; b) No intervention - 5 years; 33% case-finding
efficiency (CF) and all cases on standard regimen (SR) for 6 - 50 years; c) No intervention - 5 years; 33% CF and
all cases on SR for 6 -25 years; 33% CF - 20% cases on SCC; 80% on SR for 26-35; 40% CF - 40% on SCC and
60% on SR for 36 - 50 years.
* (Calculated on declining prevalence rates of cases (initially by 3.8% per year) decelerating with time, as per model(48).
Source of Data: Balasangaineshwara, Chakraborty, Chowdhuty
. (48)-.
NOTE: 'P'=Prevalence; 'Popn'=Population;
APP.P.No.l
1
Appendix Table (iii): PREVALENCE OF TUBERCULOSIS AMONG POPULATIONS IN
CENTRAL INDIAN DISTRICT (by some social attributes in 1982)
Selected social
attributes
Prevalence of culture positive tuberculosis / 1000 population
Popula
tion^)
RURAL
URBAN
Male
Female
Total
Sex Ratio
Male
Female
Total
Sex Ratio
Place of Residence
Kutcha Houses
60.04
3.11
1.64
2.40
190
2.63
1.40
2.01
188
Semi pucca
27.88
2.05
1.56
1.62
131
2.26
1.29
1.79
175
Pucca Houses
12.08
1.13
0.75
0.95
151
2.51
1.55
2.04
162
NIL
38.52
3.33
1.67
2.27
199
3.50
1.87
2.55
187
Primary
36.06
2.33
1.11
1.76
210
1.98
0.70
1.42
283
High School
22.41
1.60
1.03
1.24
155
2.16
1.08
1.79
200
Graduate & above
2.93
0.53
0.34
0.48
156
1.51
0.59
1.31
229
Others
0.08
Education
Religion
Hindus (Cat'A*)
48.14
1.37
0.97
1.18
141
2.56
1.42
2.29
180
Hindus (Cat'B')
29.29
2.79
1.42
2.13
196
2.47
1.23
1.87
201
Neo- Budhists
15.56
2.79
1.32
2.08
211
2.52
1.38
1.98
183
Muslims
3.69
4.07
2.22
3.18
183
2.56
1.58
2.09
162
Others
3.31
0.84
0.19
0.53
442
2.94
2.31
2.64
127
100.0
2.05
1.16
1.62
2.53
177
In all
NOTE: Cat = Category; SAGED 5 YEARS AND OVER: 687,401 (sex-ratio: 108) ;
1.38
184
1.98
Source: Nayar S et al{25)
APP.P.No.ll
I
Appendix Table (iv): PREVALENCE OF TUBERCULOSIS AMONG POPULATIONS IN A CENTRAL
INDIAN DISTRICT (by selected economic criteria, in 1982)
Selected
economic
criteria
I
I
I
I
I
I
I
I
I
Prevalence of culture postive tuberculosis/1000 population
Popu
prop
(%)
Male
Total
Female
Sex Ratio
(M/F)100
Male
Sex Ratio
(M/F)100
RURAL
URBAN
lncome(in Rs. per
month/capita)
Total
Female
<100
39.84
2.93
1.45
2.18
200
2.72
1.28
2.01
212
100-199
46.00
1.94
1.18
1.58
164
2.42
1.54
2.01
157
200-299
12.51
1.29
0.86
1.09
150
2.35
1.23
1.83
191
>300
1.65
1.81
Non-workero
26.82
3.13
1.36
1.76
230
2.22
1.57
1.73
141
Student
29.01
0.48
0.41
0.45
117
0.50
0.32
0.42
156
Service
5.34
1.65
1.18
1.61
140
2.75
5.20
2.96
53
Professional"
2.02
3.40
8.49
3.73
40
4.91
Cultivator
14.95
3.25
6.80
4.05
48
3.50
2.02
3.06
173
Agri-labour
16.39
2.56
1.14
1.81
225
3.37
1.74
2.49
194
NonAgri-labour
3.92
4.60
1.09
3.96
422
4.51
2.20
3.99
205
Others
1.54
3.86
2.53
. 3.64
153
7.02
2.45
6.42
287
In all
100.00
2.05
1.16
1.62
177
2.54
1.38
1.98
184
0.99
1.53
1.17
Occupation:
4.48
NOTE: Popn= Population; Prop=Proportion; ♦ Population aged 5 year and over: 687,401 (Sex Ratio: 108);
□Includes house-wives; "Includes petty-traders.
Source: Nayar S et al(25)
Appendix Table (v): SUGGESTED REVISION OF AVERAGE TUBERCULOSIS RATES (INDIA)
Suggested Rate
Correction
(X)
Currently used
RAD
16.0
(10.0 - 19.0)
0.2
3.0
(2.6 - 4.7)
BA
4.0
(2.0 - 8.0)
1.4
6.0
(3.0- 11.0)
Total
20.0
(13.5 - 25.0)
BA
Rad
_1_
4
9.0
2
1
(Rate per 1000 popn x-rayed)
RAD Radiologically active, bacteriologically negative; BA “ Bacteriologically positive (culture)
APP.P.No.lll
Appendix Table (vi): USES OF EPIDEMIOLOGY-TUBERCULOSIS IN INDIA
Presented below are some of the epidemiological features of the disease and their significance, viewed as a rationale for the activities under the National Tuberculosis Programme
(NTP) with particular reference to the epidemiological situation in India. The likely interpretation of data and inference regarding the epidemiological situation in the country is
also given:
Summary of epidemiological
observations from: (a) global studies;
(b) Indian surveys
Comments/inference on likely trend
or epidemiological situation in India
Epidemiological rationale
of NTP in India
1
2
3
(a) Changes in disease trend over a short span of time
are not expected, except when efficient interventions
are undertaken as in the Eskimos (hypothetically
possible). Transient changes in the epidemic curve may
occur, e.g., through war, famine etc., but the trend
resumes its natural course after their effects
disappear(secular trend).
(a). Tuberculosis programme should be a long term
programme. Vertical programmes not suitable. Case
finding/treatment activities to be carried out as service
component of an integrated health care delivery
system.
(b) Two points of observations,separated by even 10-25
years or more,are so close to each other in the context
of the epidemic curve spanning several centuries, that
quantitative changes cannot be measured, unless
massive (which is unlikely).
(c) No all India repeat sample survey at small intervals
of 10-25 years called for.
Wide spread tuberculinisation has taken place, with the
inference that tuberculosis curve is in endemic phase in
the country.
Almost a similar and uniform kind of programme is
required all over the country. No special programme
from place to place was formulated for urban slums
etc., considering the infancy of the national endeavour,
at the time it was launched!
(1) Tuberculosis is a long term epidemic spanning
several conturies. .
(2) Tuberculosis problem is more or less spread all
over the country. Difference in disease prevalence
rates between area to area not statistically significant
(barring a few exceptions eg., Raichur and urban
slums eg., in Calcutta).
(b) No quick change in situation to be expected.
APP.P.No.lV
(3) Prevalence rate of case is same for the rural and
urban areas.
Disease not likely to be in the spreading phase: Probably on the
descending limb.
In absolute number, 80% of the total problem is
distributed in rural areas (since 80% of the population
live in villages). Hence, tuberculosis services should
cover rural areas adequately. Emphasis on spread of
programme.
(4) About 38% of persons all ages both sexes and almost
70 % of males above 40 years of age infected. About 2
% are diseased. Prevalence of bacillary cases: 0.4%.
Mortality rate: 0.09%.
The wide gap between the rates may mean that the disease is on
the descending phase.
Presence of 38% of total persons infected in the
community may mean that eradication cannot be
conceived as a goal.
(5) Prevalence rate of infection and disease as well as
mortality are more in males than females.
The disease is beyond the peak, probably in the descending limb
of the curve or endemic phase.
(6) There is a decreasing trend in the infection rate of
about 2% per year, over a long term observation for a
period ranging from 5-25 years or more among children
(from longitudinal surveys of NTI). But the same is not
seen in the adjoining areas of Tumkur, Doddaballapur
and in the neighbouring state of Tamil Nadu (the last is
over 15 years).
Probably represents a secular trend of infection rate. Tuberculosis
situation may be on slow downward trend in some areas and not
changing in some other areas. It is logical to postulate different
epidemiological age from area to area in India, given its vast
expanse.
Surveillance system should be developed to study
infection rate in different parts continually, with
provision for stratification even within districts. This
could serve as effect-evaluation of the programme, if
performed every 7-10 years, area wise.
(7) Pulmonary tuberculosis is an adult disease.
Population in 0-19 years (comprising 50% of total
population) contain only 7% of total prevalence cases.
Remaining 93% of cases are distributed in population
aged 20+ years. In the first of the longitudinal surveys,
in Bangalore area, the proportion of cases above 40
years in age was around 50% (0-39 : 40+ yrs::53:47),
which was in about 20% of population. In another 30%
of population, i.e., in those 20-39 years age group, 43%
of cases were distributed.
Proportional concentration of disease in adults may mean that
disease is beyond the peak. It is most likely that the epidemic
curve is not on ascending limb.
Since cases in adults can be easily diagnosed by
simple tools (microscopy) from among symptomatics,
disease among relatively articulate adults is possible to
be tackled under a public health programme. (Note:
80% of cases are aware of symptoms and 50% are
action taking). Had the disease been more prevalent in
children, control programme might not have been
feasible (Note: Inarticulate children and difficult
diagnostic tools would pose problem: hence
programme for wide application would have been less
feasible).
Even as the population aged 40+ would contain 50% of cases, the
public health significance of young adults of between 20-39 years
in age containing 43% of cases cannot be too over-emphasised as it happens to be the most productive segment in population.
Similar is the situation in women, where the disease burden is
borne by those in the reproductive age, nearly half of the cases in
women being in this age group.
APP.P.No.V
8. Relatively higher and higher concentration of
cases in higher age groups has occurred in later
surveys as compared to earlier surveys. In later
surveys in Bangalore rural areas, about 80% of
cases were detected among those in 40+ age group.
May mean that tuberculosis is in declining phase.
Programme interference-efficiencies be augmented to
hasten the decline.
9. Prevalence rates of cases and suspect cases,
reveal almost no change in a period of over 20
years from different surveys in different areas
No change is expected over a relatively short period of time in
disease rates which are already low. Moreover disease is not in its
spreading phase: may be on a descending limb or in endemic
phase.
No all India repeat sample survey for disease prevalence
may be indicated, as this may not yield much additional
information.
10. However, the incidence of smear-positive cases
in the community is observed to have dwindled in
23 years in Bangalore rural area from around 65 to
23 per 100,000 .
This is commensurate with fall in the annual risk of infection
(ARI) from 1% to 0.6% for the area. The ARI in most other
areas, except possibly for Kashmir, are static over the years.
Slow downward trend of tuberculosis in the area, along
with high transmission, calls for a highly efficient
programme.
The high ARI with no or small extent of decline below 3% per
year, mark out India to be one of the high prevalence countries,
together with the sub-Saharan African countries.
11. Nearly 10% of all causes crude mortality in the
community are contributed by death due to
tuberculosis (tuberculosis mortality rate: about 90
per 100,000) .
12. (i) Mortality rate decreasing with time from
survey to survey, but is still high .
(ii) Survival rate of cases diagnosed in later surveys
were better as compared to in earlier rounds of
longitudinal surveys. Paediatricians generally report
seeing less of miliary, meningeal or fulminant
forms of tuberculosis. Same is the experience of
tuberculosis specialists, working in clinics.
Tuberculosis is a major public health problem and deserves
appropriate priority.
i) Disease is on downward trend or in the endemic phase.
ii) Policy of BCG vaccination to younger children might have
been effective in revising the incidence characteristics in children,
by arresting haematogenous dissemination.
Better case-holding should be attempted to save life.
Treatment services to be widely distributed through
integrated delivery approach.
BCG vaccination programme to be continued in younger
population (0-1 year or 0-4 years).
APP.P.No.VI
c
ACKNOWLEDGEMENT
A sense of gratitude is expressed to:
1. ACTIONAID India Bangalore: DrT D Daniel Coordinator, Health Unit, for liberal facilities offered.
K S Sunitha for secretarial assistance on the computer.
2. WHO SEARO: Dr M V H Gunaratne Regional Adviser (CD), Dr S Radhakrishna ORC (TB), and Dr
Tom Frieden, for requisitioning the work in the first place and constant interaction followed by
indepth analysis and comments to improve the draft, as it was ready.
3. WHO Geneva: Dr Paul Nunn (incharge. Evaluation, WHO Global TB Division), who has been a
valued friend and guide in recent times; as also Dr Chris Dye (TRS Resident Epidemiologist): for going
through the Report to offer their suggestions (the latter for favour of a personal discussion on it as
well).
4. Mr S S Nair and Dr G D Gothi; who had shaped many of the studies quoted in the Report, for
meticulously reviewing it at the draft stage.
5. Dr Nagraj Medical Officer ICMP attached to Regional Health Office Bangalore for assistance with
regard to creation of some of the Figures.
APP.P.No.VII
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