DDT, the miracle insecticide turned environmental bogeyman, is
once again playing an important role in public health. In the
malaria-plagued regions of Africa, where mosquitoes are becoming
resistant to other chemicals, DDT is now being used as an indoor
repellent. Research that I and my colleagues recently conducted
shows that DDT is the most effective pesticide for spraying on
walls, because it can keep mosquitoes from even entering the
room. The news may seem surprising, as some mosquitoes worldwide
are already resistant to DDT. But we’ve learned that even
mosquitoes that have developed an immunity to being directly
poisoned by DDT are still repelled by it. Malaria accounts for
nearly 90 percent of all deaths from vector-borne disease
globally. And it is surging in Africa, surpassing AIDS as the
biggest killer of African children under age 5. From the 1940s
onward, DDT was used to kill agricultural pests and disease-
carrying insects because it was cheap and lasted longer than
other insecticides. DDT helped