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Using DDT to Battle Malaria

A malaria control worker in protective mask and clothing sprays DDT in a hut in South Africa's KwaZulu-Natal province.
Jason Beaubien, NPR News /
A malaria control worker in protective mask and clothing sprays DDT in a hut in South Africa's KwaZulu-Natal province.

The United States banned DDT in 1972 and environmental groups are trying to outlaw the pesticide worldwide. But in developing countries, it continues to be a cost-effective way to combat malaria, a disease that kills more than 1 million people a year in Africa.

South Africa has resumed the use of DDT in its fight against mosquitoes that carry malaria. Public health officials in Pretoria say DDT has been dramatically successful. Since South African health officials resurrected a program to spray houses with DDT, the number of malaria cases and deaths has plummeted, NPR's Jason Beaubien reports.

Malaria is the second-leading cause of death in Africa after AIDS. After South Africa stopped using DDT against the disease in 1996 malaria cases climbed steadily -- from 11,000 in 1997 to 42,000 just three years later. In 2001, South Africa went back to spraying houses with DDT and malaria cases plummeted to pre-1997 levels.

In the town of Ndumo near the South African border with Mozambique, the regional health clinic is very quiet this year. Three nurses sit in a back room with nothing to do, Beaubien reports. One of them, Chabuli Ngongo, has worked at the facility for 10 years, and says things haven't always been so peaceful.

"In 1999 and year 2000 all the staff here were suffering from malaria," Ngongo says. "I had malaria myself four times."

During the malaria season of 2000, more than 7,000 people were diagnosed with the disease at the regional clinic. Almost 100 of those patients eventually died. During the first two months of 2003, the clinic has seen only 21 people with malaria. Ngongo attributes the dramatic decline primarily to the reintroduction of DDT.

"It has gone down a lot," Ngongo says. "I think it's because of the spraying."

South Africa also distributes insecticide-laden bed nets in malaria-prone villages and sprays mosquito breeding pools with larvicide.

The U.S. Environmental Protection Agency describes DDT as a "persistent, bio-accumulative and toxic pollutant." The EPA says it damages the liver, the nervous system and can make people infertile. It was banned in the United States in 1972, but it is so potent that traces of DDT can still be found in the Great Lakes and other waterways.

DDT's longevity makes it a dangerous pollutant but it also makes it a highly effective mosquito killer. In South African towns, DDT sprayed on the interior walls of houses will still be lethal to mosquitoes eight to 12 months later, making for a cheap weapon in the anti-malaria arsenal.

Though other African countries use DDT -- including Swaziland, Madagascar, Uganda and Ethiopia -- its use remains controversial. Mozambique health officials worried about the long-term effects of the pesticide and have refused to use it. Zimbabwe gave up DDT out of concern that traces of the pesticide might be found on its lucrative tobacco crop.

The World Wildlife Fund has called for a global ban on DDT but supports South Africa's limited use of the substance for malaria control.

Richard Tren with the group Africa Fighting Malaria says the campaign to ban DDT worldwide is coming from Western environmentalists who don't appreciate how lethal malaria is in Africa. "The chances that someone is going to die of malaria in the U.S. is practically zero… so you don't need to worry about it. But the risks that people face in Africa are completely different and we need different tools."

Tren and officials with the South African Ministry of Health say they've seen no adverse effects from DDT on the people whose houses have been sprayed. Health officials say DDT has been a lifesaver and that the country's dramatic reduction in malaria couldn't have happened without it.

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Jason Beaubien is NPR's Global Health and Development Correspondent on the Science Desk.