40 Countries Will Try Fighting Malaria Without DDT

The non-chemical techniques range from eliminating potential mosquito breeding sites and securing homes with mesh screens and bed nets to deploying mosquito-repellent trees and fish that eat mosquito larvae.

The goal is to achieve a 30 percent cut in the application of DDT worldwide by 2014 and a total phase-out by the early 2020s if not sooner, while staying on track to meet the malaria reduction targets set by the World Health Organization.

"WHO faces a double challenge - a commitment to the goal of drastically and sustainably reducing the burden of vector-borne diseases, in particular malaria, and at the same time a commitment to the goal of reducing reliance on DDT in disease vector control," said WHO Director-General Dr. Margaret Chan.

A couple in Kenya sleeps under an insecticide-treated bed net. (Photo by Andy Crump courtesy TDR/WHO)

The new projects planned for Africa, the Eastern Mediterranean and Central Asia follow a successful five-year demonstration of alternatives to DDT in Mexico and Central America where pesticide-free techniques and management regimes have helped cut cases of malaria by over 60 percent.

The new projects were announced in Geneva during the ongoing meeting of the Parties to the Convention on Persistent Organic Pollutants, known as the Stockholm Convention.

Under the Stockholm Convention, governments have agreed to ban a "dirty dozen" persistent organic pollutants, including DDT, on environmental and health grounds.

A specific and limited exemption was made for the use of DDT to control malaria, because it was recognized that in some situations adequate alternative control methods were not available.

High levels of DDT can affect the human nervous system causing excitability, tremors and seizures. Studies in rats have shown that DDT can mimic the action of natural hormones and so affect the development of the reproductive and nervous systems.

Health officials have expressed a long-standing and growing concern over the use of DDT and evidence that in many countries there is increasing mosquito resistance to the pesticide.

Still, concern over DDT is matched by concern over the global malaria burden. Close to 250 million cases a year result in over 880,000 deaths. So any techniques used to reduce the use of DDT must ensure that a spike in malaria cases does not result.

The funding agency Global Environment Facility will contribute close to $40 million to the new DDT-free projects being spearheaded by the World Health Organization and the UN Environment Programme.

"The GEF is investing in these projects to take decisive action toward ridding the world of dangerous chemicals now and forever," said Monique Barbut, chief executive and chair of the GEF, which is funding over half of the initiative. "The dividends from these investments will mean a cleaner, safer and sustainable environment for future generations," she said.

Projects are now going global with several new, five-year regional demonstrations of sustainable alternatives to DDT launched, or set to be launched over the next 12 months.

One involves Eritrea, Ethiopia and Madagascar and another, larger regional initiative involves Djibouti; Egypt; Jordan, Morocco; Iran, Sudan, Syria and Yemen.

A third project involves Georgia, Tajikistan and Kyrgyzstan in the Southern Caucasus and Central Asia with a possibility of adding neighboring countries.

Another project is focusing on Kenya, Tanzania and Uganda in order to develop a "Decision Taking Tool for Governments" that allows them to evaluate health, social and environmental impacts and policy tradeoffs.

Bed nets keep out mosquitoes in Nicaragua. (Photo by Roaming Leah)

The first of the demonstration projects, which began in 2003, was coordinated by the Pan American Health Organization of the WHO in partnership with the ministries of health of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama where DDT has been sprayed in homes and onto water bodies to combat malaria since the 1950s.

More than 89 million people in Central America live in areas suitable for malaria transmission; of these, 23.5 million live in highly endemic areas.

Various malaria control strategies and techniques have been tried and evaluated including community participation as central axis of the control activities.

Parasites were destroyed through rapid diagnosis and treatment, including improved counseling and supervision of oral treatments.

Reduction of contact between mosquitoes and people was achieved with treated bednets, meshes on doors and windows, the planting of repellent trees like neem and oak and the liming of households

Mosquito breeding sites were controlled by clearing vegetation, draining stagnant water ditches and channels and the use of biological controls such as fish and bacteria in some countries.

Places near houses that attract and shelter mosquitoes were eliminated by the cleaning areas in and around homes and the promotion of personal hygiene.

The project achieved a 63 percent reduction in malaria cases and a more than 86 percent cut in ones linked with Plasmodium falciparum, the malarial parasite that causes the most severe kind of infection and the highest death rate globally.

The researchers point to other benefits including the strengthening of national and local institutions involved in combating malaria; improved scientific data on DDT contamination of communities and action on stockpiles of persistent organic pollutants.

During the Central American demonstration project, more than 136 tons of DDT and over 64 tons of chemicals such as toxapehene and chlordane were scheduled for export and destruction under a separated but related UNEP treaty, the Basel Convention on transboundary hazardous waste.

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