The Hindu : Tamil Nadu / Chennai News : Fight against mosquitoes: some home truths

Online edition of India's National Newspaper
Monday, Sep 04, 2006

Tamil Nadu

Tamil Nadu - Chennai

Fight against mosquitoes: some home truths

Karthik Subramanian

Chikungunya-causing Aedes aegypti proliferating

CHENNAI : Chennai residents are learning to swing a tennis racquet and it has nothing to do with their fascination for the sport.

"Fly swatter," a Made in China contraption, available in several departmental stores in the city, is a handy weapon against mosquitoes. Instead of the tennis strings, the Rs.120-swatter has two sets of coils -- connected separately to the positive and the negative nodes of a rechargeable battery. When the user swats the mosquito, the insect is trapped between the coils and gets electrocuted. The device is safe for users though.

With the mosquito menace assuming irritating proportions in some parts of the city, residents are willing to buy even the tackiest device that promises relief. There has been an unusually high number of the Aedes aegypti or the `day-biting' mosquito that is responsible for spreading chikungunya. The fear among the residents has been so pronounced that doctors say they receive patients who diagnose themselves with cikungunya even before they reach their clinics.

There is also the lurking suspicion that the traditional means of fighting mosquitoes, including mosquito repellent coils or electronic vapours, are no longer effective. S. Raman, an Anna Nagar resident, claimed he had tried every popular brand of mosquito repellent in the market but in vain. "There seems to be just no end to the menace."

Fogging efforts

Chennai Corporation has 250 portable mosquito-fogging machines and 18 vehicle-mounted fogging machines to spray three different chemicals -- pyrethrum, malathion and deltametron.

Health officials say they carry out fogging in areas susceptible to mosquito breeding once every 20 days as per the guidelines of World Health Organisation and National Vector Borne Diseases Control programme.

Yet the menace remains. A senior health official with Corporation says the reasons are manifold. "Fogging is not an end-all solution but can only be a part of a multi-pronged approach." The two waterways of the city - Adyar and Cooum - regularly get clogged at the sea-mouth. "The normal flushing of the river that happens during the tides get restricted because of the clogging and water stagnation occurs at several points of the waterways. This leads to large scale mosquito-breeding and it is impossible to carry out fogging operation along the entire stretch of the river."

Since last year, the civic agency has also carried out extensive `non-chemical' ways of tackling the mosquito menace. It has sent notices under the Public Health Act directing owners of buildings with uncovered overhead tanks to proof them.

It was estimated last year that the city had 69,283 uncovered overhead tanks. Notices have been issued in the case of 64,238 tanks so far and proofing completed for 53,318 tanks.

The civic agency has also penalised 872 persons for not responding to their notices.

Officials note that the penalty under the Act for defaulters is just Rs.50, hardly a deterrent.

Health officials say residents could help them in curtailing the mosquito menace by clearing out mosquito-breeding points within their households. (see info box). "The Aedes aegypti mosquito has a flying span of just 100 metres. So if there are too many mosquitoes in your house in daytime, chances are they are breeding right within your house or in your neighbour's house. The best thing to do would be to identify the stagnant water and cover it up."

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