URBAN MOSQUITO CONTROL AND CIVIC BODIES

Item

Title: URBAN MOSQUITO CONTROL
AND
CIVIC BODIES
extracted text: Misc. Pubn. V.C.R.C. (9) 1989

URBAN MOSQUITO CONTROL
AND

CIVIC BODIES

P.K. Das and P.K. Rajagopalan

VECTOR CONTROL RESEARCH CENTRE

Magnitude of Problem:
Urban centers like towns,cities,and metropolises play
an important role in the national economy and various
fronts of socioeconomic development.

According to 1981 census,in India 159 million (23.3%)
people were living in 3245 urban settlements of dif
ferent shapes and sizes. It needs no scientific forecast
ing to visualize that by 2000 A.D. 338 million or 31.3%
of the total population will be living in 5583 urban
centers. The growth of urban centers is also not
uniform. It is the class I cities which has grown much
faster than the others. This is evident from the fact that
the 216 class I cities contain more than 60% of the total
urban population whereas the remaining 40% of the
urban population is scattered over 3029 centers of dif
ferent shape and sizes.
This projection is based on the census definition of
urban center (the area is classified into urban area
where more than 50% of the population are engaged
in nonagricultural activity). However such classifica
tion has little or no relevance in the context of vector.

An urban area from the • jint of view of vector control
could be defined as an area where Cx. quinquefasciatus
is major man biting mosquito.

If one considc this classification more than 50% of
the Indian population will be living in areas identical
to urban area from the vector point of view but clas
sified as rural according to census. This is mainly due
to the fact that under the influence of urban centre
many peripheral villages have themselves undergone a
process of semi-urbanization.

Such unplanned urbanization manifests itself in the
form of sprawling slums with environmental pollution
and unprecedented strain on basic sanitary services
leading to prolific breeding of vectors and nonvector
mosquitoes.
Thus the enormity of urban vector and vector bome dis
ease control problem in terms of distribution shows that
over 50% of the population in India would require some
son ofprotection from urban vector.

Urban Vector and
vector borne diseas :
In India, Cx. quinquefasciatus, Anopheles stephensi
and Aedes aegypti, the respective vectors of filariasis,
malaria and dengue hemorrhagic fever are abundant
in urban centers. It is estimated that approximately 82
million people (more than 50% of urban population)
are exposed to risk offdarial infection in urban areas.
The actual malaria situation in urban areas is not clear,
as the urban malaria scheme is in operation only in 125
urban centers which alone contributes to more than 10
% of total malaria cases in the country. The gravity of
the problem due to other vector borne disease can not
be assessed as they either remain undetected under the
garb of PUO (Pyrexia of Unknown Origin).
Amongst the vector mosquito Cx. quinquefasciatus is
the dominant species in almost all the urban centers,
whereas density of An. stephensi and Ae. aegypti vari
es from place to place and season to season. In addi
tion, Cx. tritaeniorhynchus (vector of Japanese en
cephalitis) and An. culicifacies (vector of Malaria)
are also present in peripheral areas of some of the
urban centers.

The high vector density in the urban areas is the direct
consequence of unplanned urbanisation and gross mis
management of the environment over the years. The
problem is further aggravated by faulty engineering
practices.

Present Vector Control Strategy:
At present vector control in urban area is linked with
disease control programmes like Filaria and Malaria.
Since vector control is a part of disease control
programme, efforts are made only when malaria ap
pears in epidemic proportion. However, the most
common urban vector Cr. quinquefasciatus does not
evoke much response from disease control program
mes as it transmits filariasis, a disease which causes low
morbidity and no mortality and mostly the poorer sec
tion of the community suffers. Therefore it will not be
an exaggeration if one concludes that the vector con
trol in urban area is practically non existent. Whatever

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is being done by the disease control programme is pal
liative in nature and no sustained effort is made to con
trol vectors. These measures at best can be termed as
public relations measure rather than public health
measures. The national strategy on filariasis control is
directed against the immature stages of the vector and
relies heavily on insecticides, Inspite of heavy finan
cial inputs for many years the programme did not make
any dent in the vector problem. This is mainly due to
the fact that more and more breeding places are added
every year to already existing ones, whereas the resour
ces to control were not increased proportionately.
Moreover these methods have to be repeated because
of the temporary effect of these methods and des
tabilisation of host - parasite interaction. Most impor
tant of all is the improper utilization of insecticides.

What should be done ?
Choice of method in urban vector control: Integrated
Vector Management should be followed with the em
phasis on source reduction and environmental
methods.

Integrated vector management emphasizes the utiliza
tion of all appropriate technological and management
techniques to bring about an effective degree of suppres
sion in a cost-effective manner (WHO. 1983).
Since urban vector problem is due to gross mis
management of environment, only environmental
management can provide long term solution which is
known to reduce the carrying capacity of the environ
ment. Breeding of vectors in the habitats present in an
urban areas is preventable by various environmental
methods and are described elsewhere. The VCRC ex
perience at Pondicherry, Bangalore, Mangalore,
Kovur, Hyderabad and other urban centers clearly
shows that the vector problem is purely related to the
poor sanitary condition of the town. The Government
of India is aware of these and had issued the following
guidelines in 1969.

However, while nothing is done about the first two
recommendations, only part of the recommendation
No.3 is being implemented i.e carrying out recurrent
antilarval measures without minor engineering work.
Recommendations 1 and 2 can not be implemented by
the national programme since these fall under the
purview of departments dealing with Housing and
urban development, water supply and sanitation.

Who should do vector control
Since urban vector problem is related to sanitation,
vector control has to be delinked from the disease
control programmes and linked with sanitary services
under the direct supervision of a public health en
gineer. If urban vector control is linked with sanita
tion,vector control can be achieved by environmental
methods in a most cost effective manner by the least
trained manpower. This could be done best if local
bodies are made responsible for all local problems in
cluding health. Local bodies are accountable to the
public. Multiplicity of departments only increase the
cost of health delivery and reduces the effectiveness of
the programme. The coordination of functions of
these departments by various (inexpert) committees
has not been very successful.
(i) A Public health engineer should be delegated with
the authority as well as responsibility of Sanitation and
Public health in urban areas. The health department
of municipality should only monitor and advice the
public health engineer from time to time.
(ii) All the operational staff available in urban areas
for malaria or filaria control should be transferred to
municipalities which should be made the nodal agen
cy for vector control in urban areas.

Following steps should be taken by the local bodies
before undertaking any control measure.

i.

prevention of filariogenic condition in town
expansion and in new townships.

Identifying the Problem

ii.

adequate arrangement for disposal of
sewage and sullage

a. Extensive studies on disease epidemiology and ecol
ogy and behaviour of the vector species should
precede the starting of planning process.

recurrent antilarval measures using malaria
oil throughout the year along with minor
engineering work.

b. Study the functioning of ongoing control
programme to identify the constraints, with scope for
improvement,if any. i.e.

iii.

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i.

Technical (changes in control strategy)

ii.

Administrative (Reorganisation of power
structure)

iii.

Financial (generating resource by introducing
service oriented tax).

c.

Analyse the administrative machinery and line
of power flow.

d.

Define the role of different departments in
prevention and control of mosquito breeding.

f.

Work out operational procedure and logistics within
a time frame.

Define the role of community/beneficiary in
prevention and control of mosquito.

g.

Standardise evaluation and monitoring parameters
and methodology to be used.

Assess the expectation of the community by
assessing tolerance level.

h.

b. Survey the area for breeding places and estimate
the relative contribution from each habitat during
different season and fix of control priority

c.

e.

f.

g.

h.

Assess the resource available for mosquito
control and sanitation.
Assess the real need and priorities of the
community.

With the information collected a macrolevel plan can
be presented to the elected members of the local
bodies and should assess the political will. At this stage
a firm commitment for implementation of Public
health Act, resource allocation, and structural reor
ganisation, if any should be obtained. If a firm commit
ment is not obtained from the elected member of the
local body, the programme should be dropped at this
stage itself. Any ambiguity at this stage may create
problems later and the programme may fail later.

If the elected members unanimously decide to support
the programme then the following steps should be
taken.
i. Specify goal and objective of the programme by
spelling out what can be accomplished within the
resource available.
ii Fixing up responsibilities and duties of different
departments of local government.

Having reached an agreement,detailed microlevel
plan should be drawn by following steps.

a.

Demarcate the area into operationally
convenient zones.

Initiate laboratory and field studies to select
appropriate control strategy and dosage of different
insecticide to be applied.

d.

Reallocation of staff,assign duties,and,training.

e.

Procurement of supplies.

Implementation of the programme with a time
bound plan.

IL ROLE OF ENGINEERS
Engineers have an important role in planning, design
ing and implementing projects which are important for
the socio-economic development of the country. For
example, construction of dams for developing irriga
tion facilities have revolutionized food production,
construction works for better transport and com
munication facilities, housing and industrialisation,
etc. However, the positive impact of such develop
mental activities is overshadowed by the negative im
pact (resulting from inadequate planning, faulty
execution and lack of maintenance) on the environ
ment and well being of mankind.

"A well meant piece of engineering ill done, can give rise
to insanitary condition which may injure the health of
the very people for whose benefit it is intended" - Menon
and Pillai 1958

The major casualty of developmental process has been
found to be sanitation and health.High mosquito den
sity in industrial areas, construction sites and urban
cities are mainly due to man-made mosquito breeding
habitats. Though the urban centres are extremely
heterogenous, the common factor identified as early
as 1958 is that:

"For the most part, man made foci of mosquito breed
ingcan be attributed to the negligence and carelessness
of construction engineers" - (Leprince in Mosquito
Control in Panama).

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Therefore this manual aims at highlighting some of the
factors in engineering design and implementation con
tributing to mosquitogenic condition,and the ways and
means of eliminating the lacunae. The defects leading
to increasing mosquitogenic conditions are not neces
sarily intentional and is mainly due to either their ig
norance of certain basic tenets of sanitation of
administrative constraints.

"Engineered Mosquito
Breeding Sites"
Mosquito breeding sites can be broadly classified into
the following categories for convenience of the users
of this manual and they are:-

1. Breeding sites related to water supply
2. Breeding sites related to water disposal,
3. Breeding site related to defective construction
4. Breeding sites due to irrigation facilities and
5. Miscellaneous breeding grounds.

stagnation. This happens mainly because extensive
pipelines were laid without considering the actual
available quantum of water. Hence the engineers
should assess the real need of the people and
availability of water before laying the pipelines. Poor
quality pipes with defective joints lead to leakage of
water and formation of puddles facilitating mosquito
breeding. Engineers should make provision for
routine maintenance and arrangements for monitor
ing the water lines which are liable to be tampered, at
the planning stage itself. It has been observed that
during planning most of the engineers do not indicate
the running cost of different schemes to decision
makers. As a result once the scheme is executed it
never functions. For example in many multistoryed
building sumps are provided to collect the water to be
pumped to overhead tanks. But they do not anticipate
that the pumps may breakdown. In many instances
such pumps are never replaced and the people living
in these apartments are forced to remove the lead and
use these sumps as well which serve as ideal breeding
ground for malaria mosquito Anoheles stephensi.
This type of problem is common in government apart
ments built for the poorer sections of the society.

1. Breeding sites related to water supply:
Various methods are employed by the community to
obtain potable water. In rural India, it is usually
through tubewells or wells while in an urban set-up
piped water supply is also provided. Several
mosquitogenic conditions arise in this process. Ex
amples are:
1.1. Pipe line leakages: Supply of water in many urban
areas is inadequate and pressure is so low that water
do not reach the level of tap. As a result, the in
habitants tap the main pipeline below the ground level
by digging pits resulting in extensive leakage and water

12. Overhead Tanks: The majority of the overhead
tanks are ideal breeding ground for anopheline
mosquitoes transmitting malaria in urban areas. Egg
laying by mosquitoes can be stopped by providing a
mosquito proof lid. If it is covered with slab they should
be of the interlocking type so as to prevent any cracks.

1.3. Water Meter Boxes/ Valve chambers: Meter
Boxes are generally located below ground level and
water accumulates due to leakage from the pipes and
joints or stagnation of rain water within them thus
creating an ideal niche for mosquito breeding. Water

Plate 1

Breeding site related to water supply, (a) pipe line leakages,
(b) valve chambers, (c) public tap, (d) overhead tank, (e) unused
sump and (f) ornamental tanks.

P;.ate 2

Breeding sites due to poor maintenance (a) storm water canal, (b)
storm water drain with cavities at regular intervals, (c) improperly
closed septic tank, (d) electrical insulators, (e) storm water canal
with underground man hole in between and (f) sewage treatment
plant.

Plate 3

B

Breeding sites related to water disposal (a) cess pit, (b) box
drain, (c) gully trap, (d) blind end drain, (e) cement tank and
(f) storm water canal carrying sullage and sewage.

Plate 4

Engineered breeding sites (a) unfinished drain, (b) pillar erected
on the storm water canal, (c) electric pole in the drain, (d) curing
yard, (e) water stagnates on the roof and (f) sun shade.

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meters should always be located above ground. If due
to aesthetic reasons, metre boxes cannot be fixed
above the ground level, then the base of the box should
not be lined so that the soil around would be able to
absorb the accumulated water . However, in areas
where water table is high this method will not work. In
such areas the meter box should be located above the
ground level. Similar measures have to be imple
mented even in valve chambers which gets filled with
water and can facilitate mosquito breeding.
1.4. Temporary storage tanks which remain unused:

Temporary tanks are constructed to tide over the
period of water scarcity. These tanks are left unused
soon after rains and facilitates rapid proliferation of
mosquitoes. Most of these tanks also accumulate solid
wastes apart from water and Cx. quinquefasciatus is
well known to exploit such conditions. Such situations
could be avoided by closing these tanks or by stocking
them with larvivorous fishes.
1.5. Disused wells: Provision of protected water supp
ly has led to the disuse of many existing wells. The
dumping of garbage and letting out the effluents into
these wells converts them into ideal breeding ground
for Cx. quinquefasciatus. Breeding could be
prevented either by permanently closing them or by in
troducing expanded polystyrene beads.

2. Breeding sites related to
waste water disposal:
2.1. Drains : Mosquito density in a locality is related
not only to the type of construction of drains but also
to their maintenance. Generally there are two types of

drains - one meant for sewage and sullage disposal and
the other for storm water. Sewage disposal in several
cities is cither through underground drainage system
or the surface drainage system.
A properly maintained underground drainage should
not create any mosquitogenic condition. But due to
lack of in built maintenance component the under
ground drainage frequently gets blocked and the
backflow of water creates mosquitogenic conditions.
The sullage water starts overflowing at various points
and forms small puddles. In order to solve this
problem, the engineers generally divert this water to
storm water canals as a temporary measure, but this
flow continues unabated permanently creating
mosquito breeding grounds all along the canal.

As far as the surface drainage is concerned most of the
towns have either a pukka (permanent) drain or a
kutcha (temporary) one. These surface drains are the
chief means of waste water disposal in most cities. Due
to faulty construction pukka drains generally do not
have any gradient along its course, and undersuch cir
cumstances when the flow of water is not rapid enough,
Cx. quinquefasciatus can breed in large numbers.
Surface drains can be kept mosquito free if properly
designed and maintained. Following points should be
kept in mind during design construction and main
tenance of the drains:

2.1.1. It should be noted that covering surface drains
the drainage system dose not become an underground
system. Covering surface drain for any reason will in
crease mosquitogenic condition. Therefore it should
never be closed so as to facilitate cleaning and larviciding if necessary. I f for aesthetic reason open drains are
to be closed the engineers should opt for proper un
derground drainage system using pipes.

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2.1.2. Construction of deep drain and deep culverts
should be avoided. The drains should not be deeper
than their width, to facilitate cleaning. The base should
slope to the centre.The design of the drains should be
U shaped and not box type. Since there is no way to
prevent entry of sullage water into storm water canals,
most of the storm water canals should be provided with
a central cunette so as to ensure proper flow of sullage
during dry weather.

2.1.3. Occasionally piecemeal construction of drains
is commonly resorted to with no proper alignment.
Before undertaking any construction work engineers
must ensure that the land along the proposed align
ment is handed over to them up to the final disposal
point. Otherwise drainage construction has to be in
terrupted due to pending cases in courts which usual
ly take years with unpredictable outcome. In this
situation the completed part of drainage will provide
ideal site for breeding. Provision must be made for
culverts across any open drain. If this is not provided,
individuals are likely to place stepping stones, fill the
channels with earth or obstruct them in other ways so
as to be able to drive vehicles or walk across and these
result in drains which are partly open and partly closed
(by the bridges). As mentioned above, this is the worst
possible situation.

pcrvision of the contractor is required, with daily
checking of the levels. Sophisticated instruments are
not needed for this.
2.1.5. Gully traps, Silt Traps and Culverts: are the
potential mosquito breeding sites and should there
fore be avoided. If calculation for culvert capacity in
dicate a depth so large that the invert level would be
below that of down stream, a w’der, shallower culverts
or a number of small culvert should be used. Other
wise, water standing in the culvert in dry weather will
produce mosquitoes.
2.1.6. Finally, a town’s rainwater drainage system can
not be allowed to discharge into a tank or lake within
5 km of a residential area. Otherwise the wastes in the
drainage water will pollute the standing water and
cause mosquito breeding in that body of water, creat
ing a health hazard. This also happens when the
drainage system discharges into a natural stream of
watercourse which in turn runs into such a body of
water. The problem could be overcome by channell
ing the flow to discharge downstream of the body of
water, or by treating it first. This is necessary only for
the dry weather flow and additional flow during
rainstorms can be discharged untreated from an over
flow weir.
2.2. Cesspits: The town and country planning

2.1.4. In general, construction of drains should always
begin at the downstream extremity and work progres
sively upstream. This order of construction will make
it possible to see that there is a continuous downward
slope along each drain.
Culex quinquefasciatus
mosquitoes can breed in water only a few centimeters
deep, so that any small departure from this rule, even
on a short section of drain, will provide a breeding site
if the water is retained at the low point. Rigorous su

authorities approve the layouts without making any ar
rangement for waste water disposal and as a result, in
many rapidly expanding towns and cities, the
authorities concerned with sanitation are unable to
provide disposal facilities to newer residential
colonies, mainly due to administrative delay and
paucity of funds. Under such conditions every
household makes a cesspit in their premises, and al
lows the waste water to stagnate. Such pits are excel

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lent breeding grounds for Cx. quinquefasciatiis and
Anuigeres stibalbatus. This could be prevented if the
engineers and town planners concerned with the ap
proval of residential areas ensure proper drainage and
sewage facilities before approving the layouts. They
should also prevent the development of unauthorised
colonies. It is also worth mentioning that due to vested
interests, engineers approve many colonies.
Mosquitoes produced in these low lying areas and un
authorised slums fly to neighbouring well planned
residential colonies.

2.3. Septic Tanks:
Septic tanks are among the most productive breeding
sites for mosquitoes. Most of the localities which
depend on drains for waste water disposal, use septic
tanks for sewage disposal. These tanks are provided
with vent pipes for the escape of obnoxious gases and
an outlet for excess water to be let out. Since a majority
of these outlets are left open, mosquitoes manage to
enter through these pipes for egg laying and prolific
breeding takes place inside these tanks. The vent
pipes have to be closed with muslin cloth or mosquito
net. Care should also be taken to ensure that the tanks
arc hermetically sealed.
Effluents from septic tanks should not be discharged
into open drains, but to a soakaway. If this is not pos
sible, a T-piece or baffle wall should be installed near
the outflow pipe to ensure that the effluent does not
contain mosquito larvae which may have developed in
side the tank.
A small crack in the cover of a lank, or a gap of only a
few millimeters between the cover and the walls, is

adequate enough for the penetration of mosquitoes
and subsequent breeding. These are commonly
formed when septic tanks arc opened for desludging,
and they may also develop cracks in course of time as
a result ot ground caving in. Septic tanks of public
latrines, should be inspected periodically and all open
ings should be closed. The most practical method
would be to cover the tank with sandy soil.

2.4. Public latrines: Most of the public latrines are very
poorly maintained and the problem is compounded by
the lack of water. The outlets of these latrines as well
as its’ septic tanks are not properly closed and enables
breeding of mosquitoes. In designing public latrines
and urinals one should consider that the sunlight is
ideal disinfectant and many germs can be destroyed by
the UV rays in the sunlight. Therefore the design
should be such that sunlight should enter atleast for
few hours in a day so that the latrines can be kept clean
and dry. The engineers should desist from construct
ing public latrine without first ensuring adequate water
supply.

3. Breeding sites in relation to
construction work:
3.1. Manhole Covers: Faulty construction of covers
for the drains and other sewage system can result in
breeding of mosquitoes. These covers have to be
suitably modified to ensure that no gap exists between
them. At many places, manhole covers are found miss
ing and efforts are neither made to prevent their pil
ferage nor to replace them. Generally the enthusiasm
of the engineers wanes as soon as the construction is
over.

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3.2. Sunshades: These structures do not have a proper
gradient and frequently the outlets are blocked, and
serve as ideal breeding ground for mosquitoes after
rains. Architects should design sunshades without any
cavity within and it should have proper gradient and
outlet pipe of larger size..
33. Roadside ditches: Small shallow pits/ditches are

created by the engineers in the process of repairing
roads on the sides of the road which accumulates
debris and water facilitating the breeding of
mosquitoes. Such stagnant puddles can be avoided if
soil/mud for such work is taken from tank beds. Thus
desilting of tanks and road building can be achieved
with the same effort.
3.4. Incomplete and delayed construction: Paucity of

funds or raw materials or in certain cases strike by the
labourers or pending settlement of claims of contrac
tor could delay the construction work undertaken for
a stipulated period of time. Water accumulates at the
basement of these incomplete edifices facilitating the
breeding of mosquitoes.
3.5. Biogas Plants: Biogas plants accumulate water in

the periphery, which in course of time gets polluted
due to the contamination of cowdung. Cx. quinquefasciatus was found to breed in large numbers in such
water bodies. Regular use of expanded polystrene
beads can curtail this breeding.
3.6. Statues and Monuments: The public as well as

several state Govts, spend a good part of their funds
on the construction of statues and monuments. Several
of these are capable of accumulating water during the
rainy season at its basements (in the case of statues) or
in small crevices formed due to the artistic moulding
of the monument. If the water thus accumulated
remains for more than a week, it can be a site for
mosquito breeding.
3.7. Ornamental tanks : All recreation centres like

parks, avenues, memorials, zoos etc. are provided with
innumerable ornamental tanks. Water in these tanks if
left unchanged for about a week can facilitate
mosquito breeding. These tanks have to be monitored
or stocked with larvivorous fishes. A fountain which
works continuously and disturbs the water surface too
can prevent mosquito breeding.
3.8. Gully traps:Yet another common defective con
slruction is the gully traps through which domestic

waste water is channelised. The cover of these traps
have small depressions in which breeding of
mosquitoes takes place.

4. Breeding sites due to irrigation facilities:
Construction of a dam can have a beneficial effect in
reducing mosquitogenic potential in the upper
reaches. The large number of isolated and scattered
breeding sites in the basin, which are so difficult to
identify or treat before impoundments, are submerged
when the area is flooded to form the reservoir.
However in the lower reaches a number of pockets is
formed due to restriction of flow by dams. In such
situations engineers must channelise the water by
proper drainage.
The major mosquito problem in an irrigation systems
is caused by the canals. In open irrigation canals, water
is distributed through several lateral canals prior to its
entry in the field. The greatest risk of creating
mosquitogenic conditions are in the minor distribution
canals and these areas are often neglected.

Any damage to the channel resulting from heavy
storms and flooding, from heavy machinery, cattle
crossing, etc., will alter the shape of the canal and
produce water pools where mosquitoes would breed.
Courses with twists and sharp bends arc liable to
erosion and silting, resulting in the formation of pock
ets with stagnant water equally suitable for mosquito
breeding.

5. Miscellaneous breeding grounds:
5.1. Electrical insulators: Electrical gadgets if kept in

open grounds can accumulate rain water and facilitate
breeding of mosquitoes till the water evaporates off
completely. Similarly broken pieces of these equip
ments too can breed mosquitoes.
53. Low lying areas : All precautions must be taken

to prevent water stagnation in low lying areas. Similar
ly storm water canals should be constructed before a
layout is given its final stamp of approval by the civil
engineers. With the rapid proliferation of towns and
cities most of the low lying agricultural lands are being
rapidly being converted into housing plots and oc
cupation of these areas without even the approval of
the authorities concerned is a common feature.

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