Nuke the mosquitoes!

Wired News has an encouraging story which introduces a possible solution to malaria in sub-Saharan Africa – nuke the mosquitos.

It’s not quite as wacky as it sounds. The IAEA – yep, the guys responsible for monitoring nuclear programs in Iraq and Iran – evidently have entomology labs where they’re breeding sterile male mosquitoes. The mosquitoes are irradiated – enough to sterilize, but not enough to kill – and then released by airplane into mosquito-infested areas. The sterile males compete with breeding males to fertilize females. Since females mate only once in their two-week lives, every female a sterile male reaches is one that won’t produce offspring.

And it works. The IAEA used this technique to eliminate tsetse flies – and the sleeping sickness they carry – from Zanzibar. It requires a lot of sterile mosquitoes – 10 to 50 times as many as fertile, wild males. Previously, Sterile Insect Technique was used to eliminate New World Screwworm in North Africa. (I don’t know if NWS was a particularly nasty insect, or whether people just found the name so unpleasant that they worked to eradicate the buggers…)

Elimination of malaria from sub-Saharan Africa would have amazing economic and development consequences. An African child dies of malaria every 20 seconds. Economist Jeffery Sachs estimates that malaria retards economic growth in African nations by 1.3% annually, due to cost of treatment and lost productivity. Given that 90% of malaria cases annually are in sub-Saharan Africa, it’s worth asking whether malaria has been a major contributor to Africa’s economic stagnation.

Mosquito sterilization isn’t the only approach to eliminating malaria. Another possible strategy involves the reintroduction of DDT. Up until the early 1960s, DDT was viewed as a miracle chemical, used in enormous quantities (80 million kilograms in 1962!), especially by American cotton farmers. In 1962, Rachel Carson published “Silent Spring”, an emphatic condemnation of the impact of chemicals on the environment. She argued that DDT accumulated in the environment, leading to the weakening of eggshells in quail and, possibly, to carcinogenic effects in humans. (Many now argue that her science was shaky, at best, notably Junkscience.com, which condemns her work in excruciating detail.) Carson’s advocacy led to an EPA ban on the chemical in 1972.

As a result, DDT finds itself in funder limbo – the US generally won’t fund programs that use DDT for malaria control as they’re afraid of the question: “If it’s not safe for Americans, why are we spraying it on Africans?” (South Africa doesn’t share this concern, and has had great success, spraying houses in malarial areas once a year – in some villages, annual malaria cases have gone from thousands a year to single digits.) But concerns over the environmental impact of DDT suggest that USAID and WHO will continue to discourage countries from using it.

Some Africans are understandably resentful of the idea that environmental concerns outweigh concerns about human life. In a moving essay, Ugandan scholar Semakula Kiwanuka observes:

Developed countries and Western environmentalists who today lead the crusade against the use of DDT, cannot escape the accusation of criminal callousness about poor helpless peoples in Africa and elsewhere in the developing world. They used DDT to eliminate Malaria in their own countries including the USA. They used DDT to eliminate Malaria in Southern Europe. Now that they are free from the deadly scourge, they care more about the birds than about African children.

Maybe sterilizing mosquitoes with radiation will get us out of this conundrum… but don’t bet on it. The IAEA acknowledges that their sterilization program has a high risk of failure. Unfortunately, efforts to balance humanitarian and environmental concerns likely do, too.

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