Vibrio Infection (Vibriosis)

*Vibrio infection facts medical author: Melissa Conrad Stöppler, MD

• Vibrio bacteria live in coastal waters. Around 12 species of Vibrio can cause a gastrointestinal illness (gastroenteritis) in humans.
• The illness produced by Vibrio bacteria is known as vibriosis.
• In most cases, the illness results from eating contaminated food, such as raw or undercooked shellfish from water that contains the bacteria.
• Exposing a wound to contaminated water can cause a Vibrio infection of the skin.
• Symptoms and signs resemble those of food poisoning and include watery diarrhea, abdominal cramping, nausea, vomiting, fever, and chills.
• Avoiding raw shellfish is one step toward prevention of vibriosis.
• Specific treatment is not necessary in most cases, but it is important to drink plenty of fluids to replace fluids lost through diarrhea or vomiting.
• Most people with a mild case of vibriosis recover after about three days without permanent effects. However, an infection with the species Vibrio vulnificus can cause a severe, life-threatening illness.

Vibrio bacteria naturally live in certain coastal waters and are present in higher concentrations between May and October when water temperatures are warmer.

About a dozen Vibrio species can cause human illness, known as vibriosis. The most common species causing human illness in the United States are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus.

Most people become infected by eating raw or undercooked shellfish, particularly oysters. Certain Vibrio species can also cause a skin infection when an open wound is exposed to brackish or salt water. Brackish water is a mixture of fresh and sea water. It is often found where rivers meet the sea.

People with compromised immune systems, especially those with chronic liver disease, are more likely to get vibriosis. Eating raw seafood, particularly oysters, and exposing open wounds to brackish or salt water can increase a person's chance for getting vibriosis.

About 80% of infections occur between May and October when water temperatures are warmer.

CDC estimates that vibriosis causes 80,000 illnesses each year in the United States. About 52,000 of these illnesses are estimated to be the result of eating contaminated food.

The most commonly reported species, Vibrio parahaemolyticus, is estimated to cause 45,000 illnesses each year in the United States.

Most people with a mild case of vibriosis recover after about 3 days with no lasting effects. However, people with a Vibrio vulnificus infection can get seriously ill and need intensive care or limb amputation. About 1 in 4 people with this type of infection die, sometimes within a day or two of becoming ill.

When ingested, Vibrio bacteria can cause watery diarrhea, often accompanied by abdominal cramping, nausea, vomiting, fever, and chills. Usually these symptoms occur within 24 hours of ingestion and last about 3 days. Severe illness is rare and typically occurs in people with a weakened immune system.

Vibrio bacteria can also cause a skin infection when an open wound is exposed to brackish or salt water. Brackish water is a mixture of fresh and sea water. It is often found where rivers meet the sea.

A clinician may suspect vibriosis if a patient has watery diarrhea and has recently eaten raw or undercooked seafood, especially oysters, or when a wound infection occurs after exposure to seawater. Infection is diagnosed when Vibrio bacteria are found in the stool, wound, or blood of a patient who has symptoms of vibriosis.

Treatment is not necessary in mild cases, but patients should drink plenty of liquids to replace fluids lost through diarrhea. Although there is no evidence that antibiotics decrease the severity or duration of illness, they are sometimes used in severe or prolonged illnesses.

To reduce your chance of getting vibriosis, don't eat raw or undercooked shellfish, such as oysters. If you have a wound (including cuts and scrapes), avoid contact with brackish or salt water or cover the wound with a waterproof bandage if there's a possibility it could come into contact with brackish or salt water, raw seafood, or raw seafood juices.

Vibriosis has been a nationally notifiable disease since 2007.

Health departments report cases to the Cholera and Other Vibrio Illness Surveillance (COVIS) system. COVIS was initiated by CDC, FDA, and four Gulf Coast states (Alabama, Florida, Louisiana, and Texas) in 1989. By the early 2000s, almost all states were voluntarily reporting.

Because Vibrio bacteria are not easily identified with routine testing, many cases are not reported.