http://news.bmn.com/news/story?day=020322&story=1

21 March 2002 17:00 GMT

by Fred Pearce, BioMedNet News

[caption and credit]

Widespread criticism is emerging about the ambitious plan to rid Africa of the tsetse fly by flooding the continent with male flies that have been irradiated to sterilize them. Experts in tropical medicine, insect physiology and ecology say the multibillion-dollar scheme is unworkable, even if the cash can be found.

"We think it is crazy. It will never work," said Hans Herren, director of the International Centre for Insect Physiology and Ecology in Nairobi.

The risk of re-infestation is particularly great because there are 22 species, which would each have to be tackled individually, he says. "When one species is eliminated, you create an ecological niche for another," Herren told BioMedNet News.

David Molyneux, director of the Liverpool School of Tropical Medicine, is equally scathing. "The approach is an insult to scientists and public health practitioners," he noted.

Sleeping sickness, the disease caused by the trypanosome parasite that the fly carries, kills an estimated half-million Africans a year, mostly in a belt between Angola and Sudan.

The parasite also causes a disease known as nagana in cattle. Its presence means most breeds of cattle cannot live in a third of the continent, which means no meat, no milk, and no traction for ploughing.

Many African governments greeted with joy the first successful program to eradicate the tsetse fly, from the Tanzanian island of Zanzibar. Last month the International Atomic Energy Agency (IAEA), which was in charge of the Zanzibar operation, announced that it had agreed with the Organisation of African Unity to a continent-wide blitz against the tsetse, using the method field-tested in Zanzibar.

The idea is to breed billions of male flies in captivity, sterilize them using a nuclear source, cobalt-60, and then spray them across the bush. The theory is that they will swamp the fertile wild males and, after a few generations, the population will die out.

"We don't deny it's ambitious," said Arnold Dyck, the IAEA scientist in charge of the Zanzibar project. The huge logistical operation to banish the fly from the entire continent could take decades and cost "five, ten or even twenty billion dollars," he admitted.

"It is hope as well as science. But we can't deny Africans the technology," Dyck said.

David Rogers, an ecologist at the University of Oxford, condemns the philosophy. "Scientists are telling lies to make their approach look feasible," he said.

The critics argue that it will never be possible to wipe out all the flies and that populations will inevitably recover in the bush, especially in Africa where vital follow-up programs rarely work.

Tsetse flies travel much farther than the IAEA claims, Rogers says, and they will re-infest any area that is cleared, he adds.

Similar efforts to clear the fly from Nigeria, Burkina Faso, Tanzania and Ghana all failed, note the critics. They argue that far cheaper strategies of limiting the tsetse fly through traps and insect repellents are much more likely to work.

Picture caption and credit:
Tsetse fly, USGS. Trypanosoma in blood smear, CDC/Dr. Myron G. Schultz.

Send us your comments for publication.

Sign up for BioMedNet News weekly email alerts

ALL INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE.  THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.