KNOY: Just ahead, coffee: a brewing controversy over the future of Ethiopia's economy and environment. First, this Environmental Health Note from Diane Toomey.

TOOMEY: One out of every four people on the planet is infected with parasitic worms called nematodes. Nematodes are also major agricultural pests attacking crops and livestock. Others, like heartworm, infect pets. There has been increasing concern that nematodes are developing resistance to drugs used to treat these infestations. But now, research at the University of California at San Diego offers hope for a safe, low-cost alternative.

For decades, organic farmers have fought off nematodes with a natural insecticide derived from a bacterium known as Bt. A number of genetically-modified crops have also been engineered to produce the Bt insecticide. The toxin acts by dissolving the intestines of insects that ingest it.

Humans and other vertebrates lack the kind of cellular receptors needed for the toxin to work, so exposure to Bt has been shown safe for people. Until now, Bt hadn't been tested on nematodes, but the UC/San Diego team found that all six nematode species used in this experiment were affected by Bt, either killing them outright, damaging their intestines, or reducing their number of offspring. Researchers say it's possible that a drug derived from Bt toxin could be developed as an effective remedy against nematode parasites in humans and other animals.

That's this week's Health Note. I'm Diane Toomey.

KNOY: And you're listening to Living on Earth.