text: Malaria is nothing new to Nairobi. Outbreaks occurred there in the 1920s, 1930s, and 1940s. What got malaria "under control" there as well as in other areas, including parts of the United States, was the introduction of DDT after World War II. The World Health Organization specifically credited DDT use for preventing a malaria epidemic from reoccurring there after a flood in the early 1960s. But after DDT use stopped due to environmental pressure, malaria returned in many places where it had been nearly eliminated, such as Sri Lanka. And DDT was banned before a malaria eradication program could be launched for most of southern Africa, where the disease now kills to million a year. In fact, the World Health Organization recently just reversed its long-held policy and now encourages DDT use there to combat malaria.