Vibrio – A Dirty Word

by Kevin A. Savoie

Vibrio vulnificus is a bacterium that occurs naturally in warm, salty, waters of estuaries and oceans. It may be found in a wide variety of environmental sources such as water, sediment, plankton, fish, crabs, shrimp, oysters, and clams. The organism is able to cause infection in humans through ingestion (typically by eating raw oysters) or through a wound caused while handling or cleaning fish, crabs, oysters, etc. An existing wound may also serve as a source of infection from the bacteria in seawater.

Fortunately, most healthy people are resistant to infection. However, individuals with certain types of chronic underlying diseases are at serious risk. Persons with diabetes, cirrhosis and other liver diseases, gastric disorders, leukemia, cancer, lung carcinoma, acquired immune deficiency syndrome(AIDS), AIDS – related complex(ARC), or asthma requiring the use of steroids, should avoid consuming raw shellfish or inadequately cooked seafood. For such individuals, Vibrio vulnificus is one of the most invasive and rapidly fatal human pathogens known. Infection in this group of individuals could result in the “primary septicemia” form in which the mortality rate is over 50%. Symptoms following ingestion generally occur within 16 to 38 hours, and include fever, chills, a decrease in blood pressure, and the development of “secondary lesions”, typically in the legs. These lesions begin as fluid-filled blisters which progress to result in extensive destruction of muscle tissue, frequently requiring amputation of the affected limb.

Persons infected with V. vulnificus through wounds also develop fever and chills, with redness, swelling, pain, and tissue destruction at the site of the wound, but do not develop the secondary lesions typical of ingestion cases. The fatality rate for wound infections is approximately 25%, with deaths occurring primarily in persons with the underlying diseases listed above.

Individuals who are considered in the “at risk” group should take the following special precautions to avoid vibrio infections:

-Never eat raw shellfish or improperly cooked seafood.

-Avoid contaminating wounds with seawater, fish or other sources.

-Avoid handling crabs, fish, oysters, shrimp with bare hands, wear gloves, long sleeves, long pants, and shoes if you must handle these products.

– Clean any wounds received from fish or other seafood or wounds contacted by seawater, mud, etc. with alcohol or other appropriate disinfectant.

Sources: and “Bad Bug Book” U.S. Food and Drug Administration.


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