Last Chance for DDT

Thanks to the pragmatism of African health officials and the efforts of some in the U.S. government, the insecticide DDT is still repelling and killing mosquitoes in Africa nations, saving thousands of people from malaria and other infectious diseases each year.

ut its days may be numbered. While the Bush administration and the World Health Organization have argued articulately in favor of DDT over the past two years, so-called environmentalists and those companies selling alternatives to DDT are pushing to prevent it from being deployed.

President Bush launched the President's Malaria Initiative (PMI) in 2005 with the explicit aim of using all the best methods for preventing the disease. As a result, last year DDT was procured with taxpayer funds for use indoors in tiny amounts in Zambia. The tactic, known as indoor residual spraying, or IRS, is cheap and highly effective, repelling and killing mosquitoes before they can bite and transmit disease while avoiding widespread, outdoor spraying. (The PMI has not procured this insecticide for any other nation, but has funded alternatives to DDT, such as deltamethrin, in Uganda, Angola, Tanzania and Rwanda.)

But developing nations are skittish. Their populations have been scared by environmentalists into thinking DDT causes cancer and birth defects; and their farmers have been frightened by EU officials and segments of the Western chemical industry into believing their crop exports will be boycotted. As a result, many African leaders have delayed re-introduction of DDT, perhaps indefinitely.
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Meanwhile, vast swathes of the anti-malaria community, including the malaria teams within national donor agencies, are quietly opposed to DDT. Agencies include insecticide spraying in their literature, but then run No-Spray programs. Aid agencies -- including UNICEF and the World Bank -- have steered clear of DDT, choosing instead to support anti-malaria experiments such as mosquito bed nets for the past decade. The managements of the donor agencies offer spurious explanations as to why DDT and indoor spraying in general shouldn't be used.

The favorite excuse is that DDT campaigns are unsustainable because they require more infrastructure to be delivered than simply handing out bed nets. Yet the evidence is that the distribution of bed nets, without significant educational support on their proper use, is not as effective as hoped. Some of the recent bed-net success stories in Kenya highlight this fact.

With the notable exception of the PMI, and occasionally the Global Fund for AIDS, Tuberculosis and Malaria, no agencies seem to want to sustain a spray program. Yet Mozambique, which has very poor health infrastructure, has managed to sustain a well-run indoor residual spraying program for more than seven years by partnering with neighboring South Africa and Swaziland. As a result of this initiative, the country's malaria burden has dramatically decreased. Rates have dropped by 88% among children in the key target areas. Instead of excuses, regional leaders made malaria control sustainable.

Such success stories about spraying are rarely reported. What is reported is any bad news about DDT. And anti-DDT bias in the academic literature is accelerating. A recent article in The Lancet Infectious Diseases Journal alleges that superior methods for malaria-control exist, yet the authors do not provide a single reference for this claim. The authors also claim that DDT represents a public-health hazard by citing two studies -- studies that, according to a 1995 WHO technical report, do not provide "convincing evidence of adverse effects of DDT exposure as a result of indoor residual spraying."

In fact, after 60 years of use there is still no solid evidence of any human harm from DDT. Yet the article in The Lancet, like so many before it, will be used by those in the field to dissuade Africans from using the insecticide.