MALARIA: Haiti

On top of the almost unimaginable devastation caused by January's earthquake in Haiti, the nation is bracing for the ravages of the rainy season. Torrential downpours have already flooded homes and turned tent cities into muddy misery. Ominously, the number of cases of malaria, which is spread by the bite of mosquitoes and which was endemic in Haiti even before the earthquake, is increasing.
To reduce the incidence of malaria, various aid groups are planning to distribute more than 3 million bed nets, an ultra-low-tech, only modestly effective intervention. What is really needed is the chemical DDT, an old, cheap and safe tool to control the vector -- the Anopheles mosquito -- that spreads the disease.
Malaria is a scourge of humanity, particularly for the inhabitants of poor tropical countries. Forty-one percent of the world's population live in areas where malaria is transmitted, and each year 350 to 500 million cases of malaria occur worldwide. The disease imposes huge costs on individuals, families and governments, which are a crushing economic burden on malaria-endemic countries and impede their economic growth. It has been estimated that economic growth per year of countries with a high incidence of malaria was 1.3 percentage points lower than that of similar countries without malaria.
A drug called chloroquine is a useful preventive but many strains of the malaria parasite in Haiti have developed resistance to it. Other drugs called artemisinins are safe and exhibit potent, rapid antimalarial activity, and in combination with other anti-malarials they have been used effectively for several years to treat multiple-drug-resistant malaria. But resistance has arisen and is increasing, so that in the absence of a vaccine elimination of the mosquitoes that spread the disease is the key to preventing epidemics.
Unfortunately, flawed public policy limits the available options.
In 1972, on the basis of data on toxicity to fish and migrating birds (but not to humans), the U.S. Environmental Protection Agency banned virtually all uses of the pesticide DDT, an inexpensive and effective pesticide once widely deployed to kill disease-carrying insects. DDT was subsequently banned for agricultural use worldwide under the 2001 Stockholm Convention on Persistent Organic Pollutants, which stigmatized the chemical and effectively constituted a prohibition.
Although DDT is a (modestly) toxic substance, there is a vast difference between applying large amounts of it in the environment -- as farmers did before it was banned -- and using it carefully and sparingly to fight mosquitoes and other disease-carrying insects. DDT remains largely near where it is sprayed, and no study has ever linked environmental exposure to DDT to harm to human health.
When DDT is used at all now, it is sprayed indoors in small amounts to prevent mosquitoes from nesting, so exposures would be low. A basic principle of toxicology is that the dose makes the poison, and with modern regimens, both environmental and human exposures would be very low.
The regulators who banned DDT failed to take into consideration the inadequacy of alternatives. Because it persists after spraying, DDT works far better than many pesticides now in use, some of which are toxic to fish and other aquatic organisms. With DDT unavailable, many mosquito-control authorities are depleting their budgets by repeated spraying with short-acting, marginally effective insecticides. Read more: http://www.miamiherald.com/2010/05/03/1610610/ddt-can-stymie-malaria-carrying.html#ixzz0oqSp6Fr8