Vibriosis

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Vibriosis

Definition

Vibriosis is a disease caused by an infection with bacteria of the Vibrio genus, most commonly Vibrio parahemolyticus or Vibrio vulnificus. Vibrio bacteria cause diarrhea, skin infections, and/or blood infections. The diarrhea-causing Vibrio parahemolyticus is a relatively harmless infection, but Vibrio vulnificus infection, though rare, can lead to blood poisoning and death in many cases.

Description

Vibriosis is a general term referring to an infection by any member of the large group of Vibrio, bacteria. The bacteria that causes cholera is in this group. Alternate names include non-cholera Vibrio infection, Vibrio parahemolyticus infection, and Vibrio vulnificus infection.

Vibrio parahemolyticus and Vibrio vulnificus are found in salt water. Infection with either of these two bacteria primarily occurs through eating contaminated raw seafood. Raw oysters are the usual source, although other seafood can carry the bacteria.

Vibrio parahemolyticus causes severe diarrhea. Vibrio vulnificus may cause diarrhea, but in persons with an underlying disease it may cause severe blood infections (septicemia or blood poisoning). Contact of a wound with seawater or contaminated seafood can lead to a Vibrio vulnificus skin infection.

Vibriosis is not very common in the United States. Most cases occur in coastal states between June and October. Between 1988 and 1991, there were only 21 reported cases of Vibrio parahemolyticus infection in the United States. Between 1988 and 1995, there were over 300 reports of Vibrio vulnificus infection in the United States.

Causes and symptoms

Vibriosis is caused by eating seafood contaminated with Vibrio parahemolyticus or Vibrio vulnificus. These bacteria damage the inner wall of the intestine, which causes diarrhea and related symptoms. Vibrio vulnificus can get through the intestinal wall and into the bloodstream.

Persons at risk for severe, often fatal vibriosis include those with liver disease (cirrhosis), excess iron (hemochromatosis), thalassemia (a blood disorder), AIDS, diabetes, or those who are immunosuppressed.

Symptoms of intestinal infection occur within two days of eating contaminated seafood. Symptoms last for two to 10 days and include watery diarrhea, abdominal cramps, nausea, vomiting, headache, and possibly fever. Symptoms of a blood infection develop one to two days after eating contaminated seafood, and include fever, chills, low blood pressure, and large fluid-filled blisters on the arms or legs. Similar blisters can also be produced by a Vibrio vulnificus skin infection.

Diagnosis

Vibriosis can be diagnosed and treated by an infectious disease specialist. It is diagnosed when Vibrio bacteria are grown from samples of stool, blood, or blister fluid. The symptoms and a recent history of eating raw seafood are very important clues for diagnosis.

Treatment

To counteract the fluid loss resulting from diarrhea, the patient will receive fluids either by mouth or intravenously. Antibiotics are not helpful in treating Vibrio parahemolyticus diarrhea.

However, Vibrio vulnificus infections are treated with antibiotics such as tetracycline (Sumycin, Achromycin V), or doxycycline (Monodox) plus ceftazidime (Ceftaz, Fortraz, Tazicef). One out of five patients with vibriosis requires hospitalization.

Prognosis

Most healthy persons completely recover from diarrhea caused by Vibrio bacteria. Vibrio vulnificus blood infection affects persons with underlying illness and is fatal in half of those cases. Vibrio vulnificus wound infections are fatal in one quarter of the cases.

Prevention

Contamination with Vibrio bacteria does not change the look, smell, or taste of the seafood. Vibriosis can be prevented by avoiding raw or undercooked shellfish, keeping raw shellfish and its juices away from cooked foods, and avoiding contact of wounded skin with seawater or raw seafood.