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 infection, called paragonimiasis, is caused by a parasite common in crayfish throughout North American. The parasitic worms invade the lungs but can migrate to the brain or under the skin. The infection is generally not fatal, and it is easily treated if properly diagnosed. But the illness is so unusual that most doctors are not aware of it. Credit: Washington University in St. Louis