In some African villages, nearly everyone is infected with Mansonella perstans, a parasitic worm that’s remarkably hard to kill. It’s resistant to standard anti-worm medications, but researchers have learned that an old antibiotic can vanquish the tiny beasts — in a roundabout way.
The parasites are stuffed with a type of bacteria called wolbachia, and apparently they depend upon those microbes for their own survival. By killing the bacteria inside of the worms, doctors can destroy the worms themselves.
To test that concept, an international team recruited volunteers with M. perstans infections from four villages in Mali, and gave 69 of them a dose of doxycycline each day. After one year, all but two of the patients who took the antibiotic were free from worms in their blood.