LSUHSC Research Identifies New Risk Factors for Parasitic Infection

A study conducted by Dr. James Diaz, professor of public health and preventive medicine and program director of the Environmental/Occupational Health Sciences Program at the LSU Health Sciences Center New Orleans School of Public Health, analyzed cases of a parasitic lung infection and found new modes of transmission and associated behaviors, identifying new groups of people at risk. Diaz hopes to raise the index of suspicion among medical professionals so non-traditional patients and those not exhibiting all symptoms but who are at risk can be diagnosed and treated to avoid potentially life-threatening lung or brain complications. The work is published in the July 2013 issue of Clinical Microbiology Reviews.

Among the organisms that can harbor the Paragonimus parasite are freshwater Asian crabs as well as native U.S. crawfish. Most cases of infection are reported from Asia or in those who have recently traveled to or immigrated from a region where the parasite is prevalent. Cases in the U.S. were rare prior to 1984. However, these days Asian crabs are being served far from home and in new ways. The parasitic infection, paragonimiasis, can occur when the crabs are eaten raw in sushi bars or alcohol-pickled called drunken crabs in martinis.

The one indigenous Paragonimus species can transmit infection through undercooked mudbugs at a crawfish boil and through exposure while floating, paddling, canoeing or camping on waterways and in areas where crawfish live. Some cases have followed consumption of raw crawfish while intoxicated. A person can become ill from eating only one. Less commonly, the parasite has been transmitted by contaminated food utensils and consumption of undercooked meat from infected animals.

The incubation period can vary from 2 to 16 weeks. Although some people can remain asymptomatic for prolonged periods, this parasitic infection can produce symptoms ranging from fever, recurrent cough, and night sweats, mimicking tuberculosis, to bloody cough, pleurisy, and pneumonia. It can cause headaches, seizures, stiff neck, and loss of vision. It can also result in death.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) now advise cooking or boiling crawfish to reach an internal temperature of 145° F. before eating. Other prevention strategies include frequent hand-washing when preparing crustaceans, avoiding contamination of utensils and serving platters, as well as cooking crustaceans to the recommended temperature of 145°F.

New laboratory and other diagnostic tests can confirm infection with Paragonimus parasites, and there is effective treatment available.

"Doctors should consider this infection in vacationers and weekenders returning from areas of the U.S. where the parasite is endemic and ask about raw or undercooked crawfish in all patients with unexplained fever, cough, high white blood cell count, and fluid around the lungs," notes Diaz. "Even without microscopic evidence, any patient with a positive history of raw or undercooked freshwater Asian crab or native crawfish and clinical symptoms should be evaluated and treated to prevent serious complications."