Vibriosis

Epidemiology Corner

April 23, 2004

Vibriosis is an illness caused by a group of bacteria in the genus Vibrio. Pioneer microbiologists claimed that these bacteria seem to vibrate, hence their name Vibrio. Perhaps the most notorious species is Vibrio cholerae, the bacteria that causes the disease cholera. In 1849, the English investigator John Snow successfully linked cholera to water consumption in London. This discovery launched epidemiology as a reputable science.

The germs causing vibriosis are usually transmitted to humans via food, particularly seafood, but contact between an open wound and water contaminated with Vibrir may also cause infection. Though rare, vibriosis is more severe than other bacterial foodborne illness such as Salmonella or Shigella. A Vibrio infection by food or water consumption is characterized by a sudden onset of diarrhea, nausea or abdominal cramps. Fever is often involved. Depending on the species, symptoms may begin as soon as one hour after ingestion (in the case of V. cholerae), four to 30 hours in the case of V. parahaemolyticus, or as long as 12 hours to three days in the case of V. vulnificus. Symptoms begin quickly compared with other bacterial foodborne diseases. Occasionally, infection is caused by infiltration of bacteria in a break in the skin or wound. Lesions on the skin that develop rapidly characterize this type of Vibrio infection. People with fishhook puncture wounds or scratches from stepping on seashells have been infected in this manner.

According to the Centers for Disease Control (CDC), about 8,000 illnesses due to Vibrio occur each year in the U.S., but only 200-300 are confirmed through laboratory culture. Approximately 60 of these Vibrio illnesses result in death each year. In Houston, roughly five cases of Vibrio infection occur each year.

Vibrio is one of the most common organisms in surface waters throughout the world. Because of this, areas adjacent to warm sea or ocean waters are the most prone to its dangers. Filter-feeding mollusks (oysters, mussels, clams and scallops, for example) ingest Vibrio easier than other sea creatures. Thus, the number of Vibrio infections tends to peak during the summer months when more people are outside for recreation and fishing and when the warm and salty environments favor bacterial growth. The peak month for Vibrio infection occurs in June for the Gulf Coast states and in August for the non-Gulf states.

According to the CDC, in the U.S, 99% of people who were diagnosed with Vibriosis in 2000 had consumed seafood during the week before illness began. Of those eating just a single seafood item, 56% ate oysters (the majority which were raw) and 20% ate shrimp.

The populations most at risk are those who consume raw or undercooked shellfish, fishermen and people who prepare crabs, lobsters or Tilapia fish. Immunocompromised persons and/or people with chronic liver disease, alcoholism or high levels of iron should be especially wary about a shellfish diet. Cooking seafood thoroughly can diminish hazards from Vibrio. Cross contamination of seafood with other foods during food preparation should be avoided.

You can read more about vibriosis on the CDC website at