Trap them all

MCD adapts new measure to combat dengue and malaria

By Sarita Bahl
Published: Thursday 15 July 2004

after the failure of its fogging drive and public awareness campaigns aimed at combating dengue and malaria, the Municipal Corporation of Delhi (mcd) has decided to use oviposition (ov) traps. This tool is widely used in Singapore -- a hot spot for the diseases.

The trap is a wide-mouthed, pint-sized jar, which is partially filled with water. It is placed in an area where mosquitoes are likely to spawn. It contains chemicals whose 'smell' attracts the female mosquitoes to lay eggs inside it. Regular search rounds are then undertaken to destroy the eggs. Based on weekly breeding data, it is also possible to identify the most vulnerable areas, which in turn can lead to effective surveillance.

In Singapore, the traps have helped keep the national annual breeding intensity of Aedes aegypti -- the dengue vector -- below two per cent since 1979. For dengue transmission not to occur, the intensity should be less than 0.001 per cent. Currently, 2,000 traps are being used by the island nation, with each costing Rs 115. mcd has acquired around 2,700 traps at the cost of Rs 2.75 per piece. There is still a shortage of about 1,000 traps, as Delhi has 185 wards. mcd plans to use 20 traps in each ward, with 10 installed permanently and the others used on a rotational basis.

Officials hope this method will help save many lives. Already four persons have died this year due to dengue. At present, the stakeout is restricted only to fogging and controlling mosquito breeding in coolers and waterbodies. "These measures are not foolproof," asserts M A Ansari, senior deputy director of the Malaria Research Centre (mrc), New Delhi. mcd has started using the traps on the behest of mrc. "The traps can help overcome the drawbacks of the present system. Moreover, they are cheap and ecofriendly," claims K N Tewari, municipal health officer of mcd.

Some experts however refute the claim. "The mosquito population is quite large, and the traps are too less. If they were the ideal solution then why undertake any other control measures?" avows R S Sharma, joint director of the National Anti Malaria Programme -- the advisory body for all vector control measures undertaken across the country.

It remains to be seen whether the new measure will prove Sharma wrong or not. At any rate, educating the community about the traps and their positioning should be high on mcd's agenda for the technology to prove successful.

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