Link: Parasite is a growing concern for healthcare professionals – Los Angeles Times.

In 1996, using an experimental test, the American Red Cross found that one in 9,850 blood donors in the L.A. area tested positive for the parasite, Trypanosoma cruzi. Two years later, it was one in every 5,400. By 2006, a more refined test detected the parasite in one in 3,800 donors. About 10% to 30% of infected people develop symptoms of chronic disease, experts say.