Vibriosis (Seafood Vibrio Bacteria Infection) Causes, Symptoms, Treatment

Every year some 80,000 cases of non-cholera Vibrio infections occur in the United States. In fact these bacteria are responsible for the majority of seafood-related gastroenteritis. While it is often a mild gastrointestinal infection, these bacteria may also be responsible for septicemia as well serious skin and soft tissue infections like necrotizing fasciitis which can lead to amputations or may even result in death. Depsite the potential seriouness of this infection, many people are still unaware of these deadly ‘bugs’ that lurk in salt water and seafood.

What is vibriosis?

Vibriosis is a bacterial infection caused by the Vibrio species of bacteria. These infections may be classified as Vibrio cholera infections (commonly referred to as cholera caused by Vibrio cholerae) or non-cholera Vibrio infections. The term vibriosis usually refers to these non-cholera Vibrio infections. Like with cholera (caused by Vibrio cholerae which is another species of the Vibrio bacteria), these non-cholera Vibrio infections are mainly transmitted through contaminated food and water. It is therefore considered as a foodborne infection.

Read more on cholera.

Although vibriosis is not widely known as other infectious diarrheal illnesses, it causes as many as 100 deaths every year in the United States alone. There has been an increase in these infections since tracking began by the Center of Disease Control (CDC). Vibriosis is more likely to affect people who eat raw or undercooked shellfish and seafood but even exposure to salt water can result in an infection.

Causes of Vibriosis

Many different species of non-cholera Vibrio bacteria can cause vibriosis. The two most common of these bacteria are Vibrio parahaemolyticus and Vibrio vulnificus. It produces and secretes several types of cytotoxins which can cause extensive damage to tissue. Some species like Vibrio vulnificus have mechanisms that allow it to avoid immune activity. This increases the bacteria’s virulence and can lead to complications like septicemia (“blood poisoning”).

The bacteria usually enter the body through the mouth as a result of consuming contaminated food or water. This mainly leads to gastrointestinal infections which results in symptoms like watery diarrhea. Vibrio parahaemolyticus is the leading cause of gastroenteritis caused by seafood consumption. However, in severe cases the infection may spread into the bloodstream.

These non-cholera Vibrio bacteria can also infect wounds and cause ear infections if contaminated water makes contact with a wound or enters the ear. People with who use antacids regularly or have diseases that cause weakened immune systems are at greater risk of developing severe vibriosis. Similarly, underlying conditions such as liver diseases like hepatitis, blood diseases like aplastic anemia and kidney diseases increase the risk of severe vibriosis.

Spread of Vibrio Bacteria

As with most Vibrio species, these bacteria require a saltwater environment and tend to thrive in warmer climates. It is therefore more commonly found in warm coastal environments where it occurs naturally although usually in small numbers. A person is more likely to contract the infections when raw or undercooked fish and shellfish are consumed, especially if it is  not refrigerated and exposed to a in a hot environment before consumption.

The bacteria can grow rapidly on fish or shellfish after it is caught and refrigeration is therefore necessary to prevent this growth. However, even fully cooked fish and shellfish may be a risk if proper sanitary practices are not followed. For example if fully cooked fish or shellfish come into contact with saltwater after cooking, then the bacteria may contaminate the meal especially if the environment is warm which speeds up bacterial growth.

Read more on foods that cause gastroenteritis.

Signs and Symptoms

The incubation period varies from 12 hours to 2 days. This is the time from when the infection is contracted to the onset of symptoms. On average, the incubation period is approximately 19 hours. Most commonly, vibriosis results in gastroenteritis. Therefore the following signs and symptoms are present:

  • Nausea
  • Vomiting
  • Abdominal pain or cramps
  • Diarrhea
  • Fever
  • Chills

The diarrhea results in profuse watery stool. Sometimes there may be bloody diarrhea, which is more common with  Vibrio vulnificus infection than with Vibrio parahaemolyticus. Dehydration can develop quickly and may cause additional symptoms. However, there are no specific signs or symptoms for Vibrio gastroenteritis. Vibriosis may also lead to skin and soft tissue infections, including necrotizing fasciitis, or septicemia in severe cases.

Treatment of Vibriosis

Most of the time vibriosis is a mild self-limiting disease. It lasts for approximately 3 days and medical treatment may not be necessary. Supportive measures like proper rehydration and bed rest is important to prevent complications such as dehydration and minimize the chances of a severe illness. However, sometimes vibriosis may result in a severe illness which is potentially life-threatening.

Antibiotics may be required in some cases of vibriosis. The following antibiotics may be considered:

  • Ciprofloxacin
  • Doxycycline
  • Piperacillin and tazobactam
  • Ticarcillin and clavulanate
  • Cefotaxime

However, there is growing concern about resistance to these antibiotics. In some cases, surgical intervention may be necessary. This may include debridement or fasciotomy. Reconstructive surgery may be considered in some cases. Amputation is a possibility if there is severe infection of the limbs and early intervention like debridement is either missed or failed to limit or stop the infection.

Prevention of Vibriosis

Vibriosis can be prevented in the maority of cases. People who handle seafood on an occupational basis are at a greater risk and protective wear, such as waterproof gloves, should be madatory. However, for most people the following measures may be sufficient to prevent an infection.

  • Avoid consuming seafood that is raw or undercooked. Do not rely on the odor as there may be no difference in the smell of seafood with Vibrio bacteria from uncontaminated seafood.
  • Keep raw and cooked seafood separate during the food preparation process. Avoid food establishments where there are questionable hygiene practices.
  • Washing hands after handling raw seafood is crucial. The hands should be thoroughly washed with a suitable antiseptic soap and running. Hand sanitizers may also be helpful.
  • Stay away from salt water and brackish water if there is an open wound. This is particularly important during the summer months. Wounds should be covered with a waterproof bandage and washed with clean water and soap after exposure to possibly contaminated water. Even small cuts may be a risk.



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