MALARIA: Cleaner environment lowers incidence

For over half a century, the battle against malaria has been waged with powerful anti-malarial drugs and potent mosquito-killing insecticides, weapons born from the wonders of synthetic chemistry. In recent years, however, fed up with the financial and ecological drawbacks of chemical warfare, malarious communities from China to Tanzania to Mexico have been forging a new way to fight the scourge, one that draws inspiration from the lessons of ecology more than chemistry. Rather than attempt to destroy mosquitoes and parasites outright, these new methods call for subtle manipulations of human habitats and the draining of local water bodies — from puddles to irrigation canals — where malarial mosquitoes hatch.The most striking example comes from Mexico, which has completely abandoned its previously lavish use of DDT in malaria control for insecticide-free methods and has seen malaria cases plummet.Like many countries, Mexico for decades relied upon insecticides to fight the disease, by spraying mosquito-killing chemicals on the interior walls of homes where blood-feeding mosquitoes rest, among other methods. Between 1957 and 1999, taming Mexico’s malaria required 70,000 tons of DDT.New, environmentally-sensitive methods, such as clearing vegetation along waterways and around homes, were introduced in Oaxaca, the country’s most malarious region, in 1998. By 2002, malaria cases had fallen from more than 17,500 to just 254, and Mexico incorporated the new methods
In Oaxaca, officials recruited volunteers to remove algae and trash from rivers and streams.into its national anti-malaria program. By 2000, Mexico had completely phased out use of DDT in malaria control; by 2002, it had phased out all other insecticides in malaria control as well, while simultaneously keeping malaria in check. No deaths from malaria were reported in Mexico in 2008, the most recent year of data available from the World Health Organization.Similarly, in Sichuan, China, new, non-chemical methods involving the manipulation of water flow in irrigation canals have led to the near cessation of malaria, with malaria rates plummeting from 4 per 10,000 in 1993, to less than 1 per 10,000 by 2004. In several counties of the province, no malaria cases were reported at all between 2001 and 2004. Similar non-chemical gains against the disease have been achieved in Dar es Salaam, Tanzania, as well.
http://www.e360.yale.edu/content/feature.msp?id=2270