Toxic DDT the answer to Africa's war on malaria?

At the recent launch of the “Racing Against Malaria” Campaign, South Africa’s health minister Manto Tshabalala-Msimang called on countries in the region to use the much vilified insecticide DDT to combat malaria.

While her call is sure to outrage the environmentalist lobby in the west for whom the highly toxic chemical is the poison celebre of the century, in the poverty stricken third world the call is likely to be given very careful consideration.

DDT, which was phased out in South Africa in the late 1990s but was later reintroduced following a dramatic rise in malaria incidence in its absence, is one of the cheapest and most effective pesticides ever to control malaria.

The chemical almost single-handedly eradicated malaria in America and Europe after the Second World War, but its use in agriculture was subsequently banned following concerns about long term environmental contamination.

Since the agricultural ban, international environmental groups such as the Worldwide Fund for Nature (WWF) have campaigned relentlessly for its elimination, arguing that as long as DDT is used in the world nobody is safe.

Unfortunately, however, in sub-Saharan Africa where almost a million people die annually from Malaria, the phrase “nobody is safe” attaches itself more readily to the malaria-carrying mosquito than to the ecology of the planet.

According to Richard Tren, the Director of Africa Fighting Malaria, “the real problem African countries face is donor agencies who are not only opposed to DDT use but especially reluctant to fund ‘indoor residual spraying’”.

Indoor residual spraying, the foremost malaria control technique, involves the annual controlled spraying of the inside walls of houses with a small amount of DDT. The spraying leaves an unsightly white residue on the walls but has been known to reduce malaria incidence by up to 90%.

“The reason (for donors’ opposition to DDT) is that they don’t consider it environmentally sustainable… but by implication they are saying that a million malaria deaths a year is sustainable.

“Where DDT has been used, thousands of lives have been saved. So you have to wonder, are the donor agencies here to please environmental groups or are they here to save lives,” Tren said.

He pointed out that DDT contaminated the environment and entered the food chain only after farmers sprayed huge quantities of it onto the soil, quantities that do not compare to the amount sprayed on the inside walls of houses.

According to Phillip Kruger, Limpopo province’s malaria programme manager, the provincial government constantly monitors the environmental impact of DDT and has, for the most part, managed to contain its effects.

“We do everything possible to prevent environmental contamination.
Our people are well trained, we only spray the inside walls of human dwellings so no DDT touches the soil and the water we use for mixing DDT is retained and re-used.

“We continuously take soil samples to make sure there’s no slip in our system. We’re also involved in studies on human exposure to DDT but until now there’s been no concrete evidence that we are harming anyone,” Kruger said.

All the same, he maintains that DDT is hazardous and that the search for alternatives is still on. In the absence of a viable alternative, however, Kruger says DDT use must be viewed as a necessary trade off.

Professor Maureen Coetzee, a malaria expert and head of Medical Entomology at the National Institute for Communicable Diseases, concurs.

While acknowledging that DDT is poisonous, has an exceptionally long half life and has been found in the breast milk of lactating mothers, Coetzee says advocating against its use in the developing world is simply inappropriate.

“When it comes down to it, if you give a mother a choice of small amounts of DDT in her breast milk or having her baby die from malaria, it’s not really a choice at all is it?” Coetzee said.

She also points out that studies done to date have not found any evidence that DDT deposits in human or mammal tissue are hazardous to health and that there has never been a single human death recorded from DDT exposure.

“We don’t know whether DDT in breast milk affects mother or child. Those kind of studies haven’t been done and they’re long term studies, the answer to that may be got in only 20 years time,” Coetzee said.

While the environmentalist lobby in the developed world might deride such positions, the gravity of the malaria epidemic in Africa today seems to have changed the minds of local conservationists.

Doctor Rob Little, WWF’s conservation director in South Africa, has the following to say about the accursed insecticide: “We dislike DDT use but we understand that if there’s no alternative right now, it has to be used in a very restricted fashion”. - Sapa

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