SYMPTOMS and SIGNS
Disease caused by Vibrios may range from mild to severe diarrhea. V. cholerae causes epidemic cholera, which produces severe profuse diarrhea that can be rapidly life-threatening. Fortunately, virulent strains of this species are rarely seen in the US. However, epidemics do occur elsewhere in the world, and travelers to Central and South America, India or Asia should contact health authorities to be informed of possible risks and appropriate precautions. V. parahaemolyticus causes a much milder diarrhea than cholera, but has been involved in several epidemics in US, including ones in New York, Texas, and even Alaska. Another Vibrio pathogen, V. vulnificus, is not a problem for healthy persons and rarely causes diarrhea. However, people with underlying complications like HIV, hemochromatosis, diabetes, and liver disease are susceptible to systemic infections that produces fever, general discomfort, and secondary fluid-filled lesions on the extremities. This disease may be lethal within 24 hours, and immediate medical attention is advised.
Vibrio diseases are generally treated effectively with antibiotics. In cases where severe diarrhea causes dehydration, forced intake of fluids and salts is prescribed orally or intravenously. A vaccine is available for V. cholerae but is only recommended for persons traveling to countries where the disease is endemic.
CAUSES and RELEVANCE to FLORIDA
In the U.S. most Vibrio diseases are transmitted by consumption of raw seafood, particularly oysters that are contaminated with either V. parahaemolyticus or V. vulnificus. These bacteria grow naturally in coastal waters and thrive with increased water temperatures during summer months in Florida. Consequently, most cases are seen only in the summer. The availability and greater consumption of fresh seafood in Florida may place certain persons at greater risk. Since the incidence of underlying conditions that predispose someone to Vibrio infections increase with age, Florida may have disproportionate numbers in the at-risk population compared to other states.
Persons with conditions that affect their resistance to disease should avoid raw seafood. In fact persons in this risk group should probably avoid uncooked foods altogether, as they may contain other potential pathogens. The cooking process rapidly destroys these bacteria and eliminates the problem. The adage of eating oysters in months with "R" in them also applies, since these are the colder months when water temperatures decline and bacterial numbers go down. However, anyone with HIV, hemochromatosis (iron overload), diabetes, any type of liver or immune disease, or taking immunosuppresive medications should avoid all raw seafood at all times.
Prepared by Anita C. Wright, Ph.D.
Associate Professor of Food Microbiology
University of Florida Food Science and Human Nutrition Department