Troubling new research indicates that a common pesticide used in mosquito nets is increasingly ineffective, weakening the cheapest and easiest way to combat malaria deaths in sub-Saharan Africa. The study, , compared malaria infection rates before and after nets treated with deltamethrin were introduced to a village in Senegal. Initial results indicated that the nets were highly effective, but by December 2010 scientists found a resurgence in new cases of the disease. Worse, nearly 40 percent of mosquitoes tested showed a genetic resistance to the pesticide, four times the amount found before the nets were first introduced. Aid agencies insecticide-treated nets as an inexpensive, technologically simple way to beat malaria, a disease that kills more than 800,000 people each year. But some analysis of nets’ and the success of the broader suggest more mixed results.
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