DDT spray scares mosquitoes away, study finds

WASHINGTON (Reuters) - Mosquitoes that carry malaria, dengue fever and yellow fever avoid homes that have been sprayed with DDT, researchers reported on Wednesday.

The chemical not only repels the disease-carrying insects physically, but its irritant and toxic properties helps keep them away, the researchers reported in the Public Library of Science journal PLoS ONE.

They estimate that DDT spray reduced the risk of disease transmission by nearly three-quarters.

Malaria affects more 40 percent of the world's population, killing more than a million people every year, most of them young children.

DDT use has been discontinued in most countries because of fears the pesticide may cause cancer and because of its potential effects on animals such as birds.

But the World Health Organization last year recommended the use of DDT in places like Africa where malaria is still common, saying the benefits outweighed the risks.

In the study, Dr. Donald Roberts of the Uniformed Services University of the Health Sciences in Bethesda, Maryland and colleagues tested DDT against Aedes aegypti mosquitoes in Thailand.

This species of mosquito does not carry malaria but it can transmit dengue and yellow fever.

"In huts sprayed with DDT, 59 of the 100 mosquitoes would not enter. Of the 41 that enter, 2 would die and fall to the floor," the researchers wrote.