Wednesday, August 15, 2007

Kenyan fish joins fight against malaria A native Kenyan fish could be used to help fight the spread of malaria, according to researchers. The study was published last week (9 August) in the journal BioMed Central Public Health.

Lead researcher Francois Omlin of the International Centre of Insect Physiology and Ecology, and colleagues from the US-based College of Health Sciences at the University of California, introduced Nile tilapia (Oreochromis niloticus) into several ponds containing mosquito larvae in the Kisii Central District of western Kenya.

Nile tilapia is known to feed on mosquito larvae, but has not previously been tested in the field as a method of mosquito control.

Fifteen weeks after the fish were introduced, the number of anopheline mosquito larvae (Anopheles gambiae s.l. and Anopheles funestus) in the ponds had decreased by more than 94 per cent, compared with a nearby control pond. Anopheline species are the main malaria-carrying mosquitoes in the region. The authors write that this is likely to reduce the number of adult anopheline mosquitoes in the area.

Omlin told SciDev.Net that fighting malaria requires an integrated approach and Nile tilapia could be one of the tools used alongside others such as insecticide-treated nets. Using the fish has other benefits, they write, namely that it is self-sustaining, does not need mosquitoes to survive, and is already an accepted food source for the people in the region.

Kenya's director of medical services, James Nyikal, welcomed more research into biological control methods, especially because mosquitoes are increasingly developing resistance to some pesticides.

But he was doubtful about the usefulness of the research. Mosquitoes often breed in small pools of water, such as pots, where you can't put fish, he told SciDev.Net.

The authors argue that fishponds of the size used in the study are a significant producer of malaria-carrying mosquitoes in the region. Omlin told SciDev.Net they are working with local fisheries on how their research can be implemented on a large scale.

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