Mosquito eaters help beat dengue fever

TINY crustaceans that eat mosquito larvae could make a big difference in the fight against dengue fever.

“We’ve had almost total success eliminating mosquitoes in 37 communes in Vietnam, and it’s been done by the local people,” says Brian Kay of the Queensland Institute of Medical Research in Brisbane, who set up a control programme with Vu Sinh Nam of Vietnam’s health ministry. There have been no cases of dengue in these communes, and the scheme will be extended to other areas.The scheme relies mainly on freshwater copepod crustaceans about a millimetre long that eat young mosquito larvae (The Lancet, vol 365, p 613). The team teach people to recognise local species of the genus Mesocyclops and transfer them to water tanks and wells where there are none. “The kids can pick them out very quickly,” Kay says.The most severe form of dengue fever, dengue haemorrhagic fever, has spread to 60 countries across the tropics. The new approach might help fight it in rural areas but is unlikely to work in cities, where there are usually too many small containers that hold water in which mosquitoes can breed. And it cannot be used in Africa because copepods can transmit the guinea worm parasite.(Source: New Scientist, February 2005)