Human paragonimiasis after eating raw or undercooked crayfish --- Missouri, July 2006-September 2010.

Paragonimiasis is a parasitic disease caused by Paragonimus trematodes, commonly known as lung flukes. Humans become infected by eating raw or undercooked crayfish (also known as crawfish and crawdads) or freshwater crabs that harbor the parasites. Paragonimiasis most frequently involves the lungs, but can affect other organs, including the brain and skin. In North America, Paragonimus kellicotti causes infections among dogs, cats, and wild carnivores, but rarely infects humans. Paragonimiasis is not a nationally notifiable condition. In September 2009, physicians from the Washington University School of Medicine (WUSM) in St. Louis published details of three paragonimiasis cases diagnosed since July 2006 in persons who had eaten raw crayfish from rivers in Missouri, prompting the Missouri Department of Health and Senior Services (MDHSS), CDC, and WUSM to collaborate in paragonimiasis surveillance and prevention. During September 2009-September 2010, six additional cases were diagnosed in Missouri. These nine patients, aged 10-32 years, had fever, cough, pleural effusion, and eosinophilia. All had eaten raw or undercooked crayfish from rivers in Missouri while on canoeing or camping trips within 4 months of illness onset. Health-care providers should consider paragonimiasis when examining patients with unexplained fever, cough, eosinophilia, and pleural effusion or other chest radiographic abnormalities and should ask those patients whether they have eaten raw or undercooked crayfish.