The leech that clung to the back of a 12-year-old girl's throat in Herat, Afghanistan, for about a week was doing what leeches do best: keeping blood flowing. The girl ended up with repeated nosebleeds, worsening trouble swallowing, and moderate anemia.
That same biology has earned leeches a place in American medicine. Leech saliva contains substances that stop blood from clotting, and the best known of them, hirudin, helped inspire bivalirudin, a blood thinner used during procedures to open blocked heart arteries. Live leeches themselves have been cleared by the FDA for marketing since 2004.
