Green solution to dengue peril

Green solution to dengue peril

PARIS : Dengue fever, a growing threat in poor tropical countries in Asia and Africa, is being gradually rolled back in Vietnam thanks to a low-tech, grassroots and environmentally friendly strategy, a study says. Dengue, of which there are some 50 million infections per year, is transmitted to humans by a day-biting mosquito, Aedes aegypti.

The disease is proliferating in shanty towns in many poor tropical countries, mainly because lack of a reliable piped-water supply forces people to keep water in barrels and tanks, and this is where the mosquitoes breed.

In research published on Saturday in the British medical weekly The Lancet, an Australian-Vietnamese team believe they are making inroads into the problem without having to resort to expensive and potentially damaging insecticides.

Their approach is based on a microscopic water predator called a Mesocyclops copepod, which feasts on mosquito larvae. The researchers innoculated large water tanks with a local species of Mesocyclops, which mopped up the larvae before they hatched. They also enrolled local communities in campaigns to distribute the helpful Meso bug to inhabitants and to clean up discarded containers that become a breeding ground for mosquitoes. Schoolchildren gave support to the aged and sick; songs, plays and quiz nights were organised which conveyed the campaign message; and one district even staged a competition for a "Meso" football trophy.

A pilot project to test the approach from 1998-2003 eradicated A. aegypti in nine communes in northern and central Vietnam, in areas where nearly 77,000 people live. That success caused the scheme to be extended, wiping out the mosquito in an additional 37 communes in Nam Dinh, Hung Yen and Hai Phong provinces, which have a population of 309,000. Incidence of dengue in the controlled areas, which reached as high as 112.8 per 100,000 population, has been zero since 2002.

The most extreme form of dengue is dengue haemorrhagic fever, of which there about 500,000 cases per year, at least 12,000 of them fatal. Before 1970, only nine countries in the world had dengue haemorrhagic fever. Today, the figure is 60, a result of air travel, surging population growth and rural exodus towards slums and shanties. The authors of the study are Brian Kay, a professor of tropical health at the Queensland Institute of Medical Research in Australia, and Vu Sinh Nam, an expert in preventive medicine at the Vietnamese health ministry. - AFP