29 September 2006

Uganda: DDT Might Fail, Scientists Warn

Kampala — THE impending move by the Government to use Indoor Residual Spraying (IRS) of DDT to combat malaria might not succeed due to lack of vital information on the malaria-carrying vectors, leading scientists have warned.

IRS involves spraying DDT (dichloro-diphenyl-trichloroethane) in small amounts on walls and other surfaces to kill mosquitoes that rest on them.

In Uganda, two mosquito species - Anopheles gambiae and Anopheles funestus - are responsible for transmitting the disease.

Anopheles gambiae is the most notorious and predominant in Uganda.

However, scientists have warned that lack of information on the vectors, particularly Anopheles gambiae, could flaw the proposed IRS and even worsen the situation.

The scientists are attending the Uganda National Academy of Science forum on health and nutrition at Speke Resort, Munyonyo. The forum is intended to provide evidence-based advice for the Government to make an informed decision.

Dr. Louis Mukwaya, an entomologist at the Virus Research Institute in Entebbe, said there was more than one species of Anopheles gambiae with distinct characteristics and behaviours.

Mukwaya said while some species were susceptible to pesticide because they fed and rested inside the house, a host of other species fed inside and rested outside. Others feed and rest outside the house.

He regretted that the Government, particularly the ministry of health, preferred operational researches to basic studies, leading to lack of basic but vital information necessary for policy making.

Kate Kolaczinski of the Malaria Consortium said, "If you are going to spray few houses leaving majority untouched then I envisage a flawed process. Resistance to insecticide could be a possibility."

Prof. William Banage of Makerere University said Anopheles gambiae has many population generations, which changed by season and surrounding factors, thus an attempt to spray DDT would spur the resistance.

Prof. Bob Snow of the Nairobi-based Malaria public health and epidemiology group, said although DDT helped the US and Europe eliminate malarial mosquitoes, that type of malaria was directly linked to the length and intensity of the rainy season, when mosquitoes are active.

In Uganda, he said, malaria is endemic because it rains throughout the year thus it would be a mistake to apply the same formula here.

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