WHO Calls for Spraying Controversial DDT to Fight Malaria
WHO Calls for Spraying Controversial DDT to Fight Malaria
The World Health Organization, in a sign that widely used methods of fighting malaria have failed to bring the catastrophic disease under control, plans to announce today that it will encourage the use of DDT, even though the pesticide is banned or tightly restricted in much of the world.
The new guidelines from the United Nations public-health agency support the spraying of small amounts of DDT, or dichloro-diphenyl-trichloroethane, on walls and other surfaces inside homes in areas at highest risk of malaria. The mosquito-borne disease infects as many as 500 million people a year and kills about a million. Most victims are in sub-Saharan Africa and under the age of 5.
For public-heath officials in countries losing the fight against the disease, the new guidelines promise difficult choices between fighting malaria and protecting the environment. The technique the WHO backs involves less DDT than what the U.S. and other countries sprayed over crops and residential areas decades ago. Still, the agency's push is certain to trigger fierce criticism from environmentalists who insist that DDT, which can take as long as 20 years to break down in the environment, is a threat to humans and animals.
It isn't clear which countries have agreed to test the new guidelines and ramp up spraying with DDT or other pesticides. Agency officials have discussed the idea with India, Indonesia, Sudan and Yemen, according to people familiar with the situation. The WHO guidelines don't address outdoor spraying of DDT, which isn't approved for malaria control.
DDT already is on a list of WHO-approved chemicals for indoor spraying. But until now, the agency hadn't strongly endorsed its use, and donors funding malaria programs were reluctant to finance purchases of it. As a result, countries hit hardest by malaria generally have been unable to afford substantial supplies. The WHO's new stance is aimed partly at encouraging even countries that ban the pesticide to help finance its use in areas ravaged by the disease.
The spraying of DDT has led to a sharp reduction in malaria cases in the few countries where it has been used, such as South Africa. Malaria experts say it is one of the cheapest and most effective forms of prevention. But it must be sprayed in more than 70% of the homes in targeted areas, and nearby regions also must be sprayed to halt mosquitoes there from reintroducing the disease.
Some environmentalists link DDT with cancer and disruptions of the endocrine system, but scientists disagree about DDT's effects on human health. The fear is that spraying DDT in high-risk areas would increase other health risks without eliminating breeding grounds of mosquitoes that spread the disease.
Wider use of DDT "is shortsighted and doesn't recognize the long-term problems and hazards," said Jay Feldman, executive director of Beyond Pesticides, a Washington group pushing for the elimination of toxic pesticides. "It behooves us to advocate the phase-out of this chemical around the world and find solutions to malaria that go to the cause of infestation." He says officials need to focus more on eliminating mosquito breeding grounds, such as standing pools of water.
Some African government officials have expressed concern that increased use of DDT could hurt exports of agricultural products to the European Union, where the pesticide has been widely banned for more than 20 years. The EU is the main trading partner for most African countries, with EU imports from developing African, Caribbean, and Pacific countries totaling some $36.04 billion in 2004.
The malaria parasite, borne by infected mosquitoes, clogs a patient's circulatory system, impeding blood flow to the brain and other vital organs. There are drugs for the disease, but some of the cheapest and most commonly used aren't very effective because the parasite has developed resistance.
Other pesticides and malaria-fighting methods have often proved to be less-effective and more costly than DDT. Insecticide-treated mosquito nets hung in sleeping areas are successful, but cost, distribution problems and varying usage make them less effective than they could be. Malaria experts say deployment of a malaria vaccine that is now in development could still be years away.
Pressure has been growing in the past few years for the WHO to support DDT more aggressively. Jon Liden, a spokesman for the Global Fund, which pays for indoor spraying of DDT or other pesticides in 41 countries, says the organization welcomes the WHO's move. "The Global Fund....is ready to finance increased use of the strategy if affected countries request it," he says.
The U.S. government has stepped up support for indoor pesticide spraying of homes in Africa. While it spent less than $1 million on such programs in 2005, it plans to spend $20 million in fiscal 2007, according to Admiral R. Timothy Ziemer, coordinator of the President's Malaria Initiative and the U.S. Agency for International Development's malaria programs. This year, the U.S. government purchased DDT for a spraying program in Zambia.
In a June letter, U.S. Sen. Tom Coburn, an Oklahoma Republican, urged European Union Prime Minister José Manuel Barroso not to boycott agricultural products from countries using DDT for malaria control. "As the experiences of South Africa, Swaziland, Mozambique and Zambia have demonstrated, DDT alone can reduce malaria disease and death rates by 75% in less than two years," he wrote. In a reply to Sen. Coburn, Mr. Barroso said that agricultural exports from African countries had not been disrupted due to DDT contamination, and that the EU adheres to the Stockholm Convention, which allows for the use of DDT for malaria-control purposes.
DDT, once hailed as a "miracle" pesticide, was first used widely during World War II to help control everything from typhus to the body lice on U.S. soldiers. Within a few years, the U.S. was free of malaria. In 1955, the WHO endorsed DDT use for a global campaign that within 12 years freed developed countries, along with parts of Asia and Latin America, from risk of infection.
But reports in the 1960s, launched by environmentalist Rachel Carson in the book "Silent Spring," that DDT was killing off bald eagles, in part by thinning their eggshells, and seeping into the food chain, raised concerns about the powerful chemical's heavy use. Environmental protest led the Environmental Protection Agency to ban the use of DDT in the U.S. in 1972. It currently is made by one company in India and two in China.
The WHO's new endorsement of DDT partly reflects a push to reinvigorate the agency's malaria-fighting operation under its chief since October, Arata Kochi. The 57-year-old Japanese public-health expert has been shaking up policies and personnel, hoping to repeat his success in the 1990s overseeing the WHO's comprehensive tuberculosis-control strategy.
Dr. Kochi has pressed pharmaceutical companies to stop selling a malaria medication that he fears will promote resistance to the only remaining, consistently effective drug against the disease. Last month, Dr. Kochi called on AIDS activists to pressure African countries that import insecticide-treated mosquito nets to remove high tariffs that sharply increase the price of the nets.
In southern Africa, where malaria is epidemic, indoor spraying is an increasingly common method of controlling the disease. Governments use a variety of pesticides, not just DDT, and more and more countries, such as Zambia and Mozambique, are combining indoor spraying with increased distribution of insecticide-treated nets. While community and other local organizations carry out other malaria efforts, indoor spraying is usually conducted by government health or malaria-control officials, because of the need to keep tabs on the chemicals.
While DDT is effective, there are alternatives, including a class of insecticides called synthetic pyrethroids, some of which are used to treat bed nets, says Kent Campbell, program director for MACEPA, a malaria control program at PATH, a Seattle nonprofit organization, and a former malaria branch chief at the U.S. Centers for Disease Control and Prevention.
The political debate over DDT impedes its effectiveness in preventing the disease, he adds. "It's extremely effective when used – as long as the discussion is not moved to pro or contra DDT," he adds.