Drug used to treat parasites in animals may offer new treatment for river blindness, study finds

Feb 10 2010

"Closantel, an older drug used to treat a parasitic liver disease in animals, may prove effective at combating river blindness in humans, a major cause of infection-related blindness, U.S. researchers said on Monday," Reuters reports (Steenhuysen, 2/8). 

"People contract river blindness, also known as onchocerciasis, when bitten by black flies that carry a nematode known as Onchocerca volvulus," ScienceNow reports. "The worm larvae mature and mate, producing up to 1000 'microfillariae' offspring per day, which migrate to the surface of the skin and to the eyes. When the microfillariae die, they cause itchy lesions that can lead to blindness," writes ScienceNow. According to researchers, river blindness affects more than 37 million people worldwide (Schenkman, 2/9).

In a study published in the journal Proceedings of the National Academy of Sciences, researchers document how closantel disrupts the life cycle, effectively preventing the worm from entering adulthood, Reuters reports (2/8).

Ivermectin is currently used to treat river blindness, but the drug "doesn't target the nearly-mature worms that cause new infections from a black fly's bite," ScienceNow continues, adding that ivermectin "controls the symptoms until the worms eventually die out. Scientists are still searching for a compound that would block infection altogether, for example by killing the adolescent worms upon arrival."

"If closantel has the same effect in humans, it could prevent infections from starting, says Roger Prichard, a parasitologist at McGill University in Montreal, Canada," who was not an author on the study, ScienceNow writes. "And because it works in a completely different way from ivermectin, he says, any strains of O. volvulus that show resistance to ivermectin in the future could be treated with closantel."

The article highlights the next steps for scientists to determine whether closantel can be used in humans (2/9).