Water Hyacinth Weeds:
- The organic waste in these waterways acts as plant nutrient and several aquatic weeds are found growing. Water hyacinth is the principal weed that grows abundantly in the waterways. These floating weeds shelter mosquito larvae in between the plants and the green foliage offers a good daytime resting shelter for adult mosquitoes. These plants do not multiply faster in clear water bodies.
- It is pertinent to point out here that the nuisance causing Culex (pest) mosquitoes do not breed in clear water. They need organically polluted water. Therefore prevention of organic pollution in these waterways is the first step towards prevention of mosquito breeding.
Over grown vegetation especially thorny bushes traps the floating hyacinth weeds. These shrubs and bushes reduce the accessibility for spraying. Periodical trimming / pruning of rank vegetation is a pre-requisite for mosquito control.
Shoreline dressing, contour dressing, lidooing forms part of minor engineering towards prevention of breeding.
Sand Barrier Removal:
- The entire effluents generated in the city finds it way into SWD/Minor drains and then into two major rivers namely Adayar and Coovum and finally discharge into Bay of Bengal.
- The sand bar formation at the confluence of these rivers prevent free discharge. Periodical removal of sand bar by the PWD/WRO department is yet another important and vital engineering activity towards mosquito control. If the mouth of these rivers is kept wide open and perpendicular to the Bay, the seawater enters into the river system during high tide and during low tide period the river water gets discharged into the sea. The intrusion of seawater prevents mosquito breeding and the tidal wave action prevents stagnation in the river system.
Almost all the waterways are encroached upon preventing free flow of water besides disabling access for the spray men. Several stretches could not be covered for regular anti-larval spray work.
Solid waste disposal into the waterways by the residents living on the banks and commercial establishments not only prevents free flow of water but also enhances the mosquitogenic conditions.
Storm Water Drains:
- As of now there is 800 Kms length network of storm water drains in the city. These drains are built to carry away rainwater during monsoon period and should remain dry during other seasons. But these drains are found with water stagnation throught the year leading to mosquito menace.
- Geographically Chennai is a plain terrain and lacks natural gradient for free RUN off.
Action Taken By Corporation Of Chennai:
In the interest of protecting the public health, the Corporation of Chennai is under taking anti-mosquito measures at a huge cost.
De-weeding, removal of rank vegetation & floating solid waste, shoreline dressing, contour dressing followed by spraying of chemical and biolarvicides is undertaken in all the water ways on weekly frequency to control the mosquito breeding. Spraying of larvicide's in all the storm water drains is undertaken weekly once to control the mosquito breeding. Fogging of the Storm water drains with portable fog machines is undertaken during daytime to control the adult mosquitoes resting inside the drains. Vehicle mounted fog machines are operated during dusk hours to control the adult mosquito density.
Malaria In Chennai:
Chennai City has become an endemic area for malaria since few decades. Nearly 70% of the malaria cases recorded in the State of Tamil Nadu is occuring in Chennai City alone. The problem is more acute in Northeast coastal areas like Tondiarpet, Washermanpet, Royapuram, Harbour, Muthialpet, Mannady, Sowcarpet, Elephantgate, Periamet, Pattalam and Pulianthope.
Bio-environmental method for Malaria control:
ACTION PLAN FOR MALARIA CONTROL ( Long Term Measures )
ENFORCEMENT OF SOURCE REDUCTION MEASURES UNDER SEC. 83 & 84 OF T.N.P.H. ACT 1939 TARGET AND ACHIEVEMENT TILL AUGUST 2005
"Anopheles Stephensi" the mosquito that transmit malaria in Chennai breeds in clear water men-made sources like wells, Over-Head-Tanks, sumps, Cisterns and other receptacles.
In order to bring down malaria a time bound Action Plan has been launched since November 2003 for source reduction by invoking sections 83&84 of Tamil Nadu Public Health Act 1939, under this enforcement, notices are served on the house owner/occupier to mosquito-proof the open wells, OHT's and sumps existing in their houses. Those who fail to comply are being prosecuted.
Q.B.C Test for Malaria - Free of cost:
Q.B.C.(Quantitative Buffycoat Analyser) Centres:
- Corporation of Chennai is also contemplating to mosquito proof the source and recover the cost of doing so from the owner/occupier as though property tax.
- Chemical larvicide's is being applied to wells, tanks, sumps, cisterns and other such clear water bodies once a week to prevent vector mosquito breeding.
- Blood smear examination for malaria detection is made available at all Corporation dispensaries free of cost and on the spot diagnosis facility and treatment for malaria is available. In order to detect hidden cases which are not detectable under conventional peripheral blood smears examination technique, expensive QBC equipment is made available for highly specific diagnosis of malaria at the following centres free of charges for the benefit of the people.