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Joan Stephenson, PhD

JAMA. 2002;287:1794.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

River blindness, or onchocerciasis, the second-leading infectious cause of blindness worldwide (after trachoma), has long been attributed to a parasitic nematode—Onchocerca volvulus—that is transmitted by the bite of black flies commonly found along rivers and streams in the tropics. Now, an international team of scientists from the United States, Germany, and England has found evidence that the main culprit responsible for disease isn't the worms themselves but bacteria that they carry (Science. 2002;295:1892-1895).

The parasitic nematode Onchocerca volvulus (shown here in a specimen from a skin nodule) carries Wolbachia bacteria that have been implicated as the cause of river blindness. (Credit: CDC/Mae Melvin)

After a person is bitten by a fly carrying O volvulus, the larvae mature into adults in nodules under the skin, eventually releasing millions of tiny offspring called microfilariae. The microfilariae can migrate and invade the eye, and their . . . [Full Text of this Article]