If you’re headed to a freshwater stream this summer and a friend dares you to eat a raw crayfish – don’t do it. You could end up in the hospital with a severe parasitic infection. Physicians at Washington University School of Medicine in St. Louis have diagnosed a rare parasitic infection in six people who had consumed raw crayfish from streams and rivers in Missouri. The cases occurred over the past three years, but three have been diagnosed since last September; the latest in April. Before these six, only seven such cases had ever been reported in North America, where the parasite, Paragonimus kellicotti, is common in crayfish.