Vibriosis also known as vibrio infections are largely classified into two distinct groups: Vibrio cholera infections also known as cholera and noncholera Vibrio infections. Vibrio are Gram-negative bacteria that are naturally found in warm, salty marine environments, such as salt water and brackish water and are present in higher concentrations between May and October when water temperatures are warmer. More than 20 Vibrio species can cause the human illness vibriosis. The most common species causing human illness in the United States are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus. Illnesses caused by Vibrio cholerae O1 and O139 strains that produce cholera toxin are defined by the World Health Organization as cholera. People with vibriosis become infected by consuming raw or undercooked seafood or exposing a wound to seawater. Most infections occur from May through October when water temperatures are warmer. Vibriosis causes an estimated 80,000 illnesses, 500 hospitalizations and 100 deaths in the United States every year 1.
Vibriosis is typically characterized by watery diarrhea, usually with abdominal cramping, nausea, vomiting, and fever. Vibrio bacteria can also cause wound or soft tissue infections. In people with underlying medical conditions, especially liver disease, Vibrio bacteria can cause bloodstream infections characterized by fever, chills, dangerously low blood pressure, blistering skin lesions, and sometimes death.
Anyone can get sick from vibriosis, but you may be more likely to get an infection or severe complications if you:
- Have liver disease, cancer, diabetes, HIV, or thalassemia
- Receive immune-suppressing therapy for the treatment of disease
- Take medicine to decrease stomach acid levels
- Have had recent stomach surgery.
Some Vibrio species, such as Vibrio vulnificus, can cause particularly severe and life-threatening infections. Many people with Vibrio vulnificus infections require intensive care or limb amputations, and about 1 in 5 people with this infection die, sometimes within a day or two of becoming ill.
Vibriosis should be considered if someone 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. However, people with Vibrio vulnificus infection can get seriously ill and sometimes need intensive care or limb amputation. About 1 in 5 people with this type of infection die, sometimes within a day or two of becoming ill.
Vibrio vulnificus and wounds
You may have heard that you can get Vibrio infection from eating raw or undercooked oysters and other seafood. But did you know you can also get a Vibrio infection through an open wound? This can happen when a wound comes into contact with raw or undercooked seafood, its juices, or its drippings or with saltwater or brackish water.
One species, Vibrio vulnificus, can cause life-threatening wound infections. Many people with Vibrio vulnificus infection require intensive care or limb amputations, and about 1 in 5 people with this infection die, sometimes within a day or two of becoming ill.
Some Vibrio vulnificus infections lead to necrotizing fasciitis, a severe infection in which the flesh around an open wound dies. Some media reports call this kind of infection “flesh-eating bacteria,” even though necrotizing fasciitis can be caused by more than one type of bacteria.
Who is more likely to get a Vibrio wound infection?
Anyone can get a Vibrio wound infection. But some people are more likely to get an infection and have severe complications—for example, people who have liver disease or take medicine that lowers the body’s ability to fight germs.
How can I prevent a Vibrio wound infection if I have a wound?
You can reduce your chance of getting a Vibrio wound infection by following these tips:
- If you have a wound (including cuts and scrapes), stay out of saltwater or brackish water, if possible. This includes wading at the beach.
- Cover your wound with a waterproof bandage if it could come into contact with saltwater, brackish water, or raw or undercooked seafood and its juices. This contact can happen during everyday activities, such as swimming, fishing, or walking on the beach. It could also happen when a hurricane or storm surge causes flooding.
- Wash wounds and cuts thoroughly with soap and water after they have contact with saltwater, brackish water, raw seafood, or its juices.
Most people with vibriosis 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 salt water, brackish water, raw seafood, or juice or drippings from raw seafood. Brackish water is a mixture of fresh and salt water. It is often found where rivers meet the sea. Although infections occur throughout the year, about 80% occur from May through October when water temperatures are warmer.
Anyone can get vibriosis. People more likely to get an infection or serious complications:
- Have liver disease, cancer, diabetes, HIV, or thalassemia
- Receive immune-suppressing therapy
- Take medicine to decrease stomach acid levels or had part of the stomach removed
You can reduce your risk of vibriosis by following these tips:
- Don’t eat raw or undercooked oysters or other shellfish. Cook them before eating.
- Always wash your hands with soap and water after handing raw shellfish.
- Avoid contaminating cooked shellfish with raw shellfish and its juices.
- Stay out of salt water or brackish water if you have a wound (including cuts and scrapes), or cover your wound with a waterproof bandage if there’s a possibility it could come into contact with salt water or brackish water, raw seafood, or raw seafood juices. Brackish water is a mixture of fresh and salt water. It is often found where rivers meet the sea.
- Wash wounds and cuts thoroughly with soap and water if they have been exposed to seawater or raw seafood or its juices.
- If you develop a skin infection, tell your medical provider if your skin has come into contact with salt water or brackish water, raw seafood, or raw seafood juices.
- Wear clothes and shoes that can protect you from cuts and scrapes when in salt water or brackish water.
- Wear protective gloves when handling raw seafood.
Vibrio and Oysters
Many people enjoy eating raw oysters, and raw oyster bars are popping up at some of the trendiest restaurants. But eating raw oysters and other undercooked seafood can put you at risk for infections, including vibriosis, which is caused by certain strains of Vibrio bacteria.
Vibrio bacteria naturally inhabit coastal waters where oysters live. Because oysters feed by filtering water, bacteria can concentrate in their tissues. When someone eats raw or undercooked oysters, viruses or bacteria that may be in the oyster can cause illness.
You can get very sick from eating raw oysters.
Most Vibrio infections from oysters result in only diarrhea and vomiting. However, some infections, such as those caused by Vibrio vulnificus, can cause more severe illness, including bloodstream infections and severe blistering skin lesions. Many people with Vibrio vulnificus infections require intensive care or limb amputations, and about 1 in 5 people with this infection die, sometimes within a day or two of becoming ill.
It is impossible to tell that an oyster is bad by looking at it. An oyster that contains harmful bacteria doesn’t look, smell, or even taste different from any other oyster.
You can get sick from eating oysters during any month of the year.
While most vibriosis cases occur during warmer months of the year, cases have been reported year-round.
The way to kill harmful bacteria in oysters is to cook them properly.
Hot sauce and lemon juice don’t kill Vibrio bacteria. Drinking alcohol while eating oysters doesn’t kill Vibrio bacteria either. Cooking oysters properly kills harmful bacteria.
Tips for cooking shellfish
Before cooking, discard any shellfish with open shells.
For shellfish in the shell, either:
- Boil until the shells open and continue boiling another 3-5 minutes, or
- Add to a steamer when water is already steaming, and cook for another 4-9 minutes.
Only eat shellfish that open during cooking. Throw out any shellfish that do not open fully after cooking.
For shucked oysters, either:
- Boil for at least 3 minutes,
- Fry in oil for at least 3 minutes at 375° Fahrenheit (191 °C),
- Broil 3 inches from heat for 3 minutes, or
- Bake at 450° Fahrenheit (232 °C) for 10 minutes.
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 salt water or brackish water. Brackish water is a mixture of fresh and salt water. It is often found where rivers meet the sea.
Signs and symptoms of Vibrio vulnificus infection can include:
- Watery diarrhea, often accompanied by stomach cramping, nausea, vomiting, and fever
- For bloodstream infection: fever, chills, dangerously low blood pressure, and blistering skin lesions
- For wound infection, which may spread to the rest of the body: fever, redness, pain, swelling, warmth, discoloration, and discharge (leaking fluids).
Your health care provider may suspect vibriosis if you have watery diarrhea and has recently eaten raw or undercooked seafood, especially oysters, or when you have a wound infection that 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.
Management of mild cases of vibriosis
Treatment is not necessary in mild cases, but patients should drink plenty of liquids to replace fluids lost through diarrhea. Antibiotics can be lifesaving in severe illnesses. Most people with mild illness recover after about 3 days and suffer no long-term consequences.
Management of Vibrio vulnificus wound infections
Vibrio vulnificus should be considered as a possible cause of infected wounds that were exposed to coastal waters. Treatment should be initiated promptly because antibiotics improve survival. Careful attention should be given to the wound site; aggressive debridement or amputation of the infected limb is sometimes necessary.
- Culture of wound or hemorrhagic bullae is recommended, and all V. vulnificus isolates should be forwarded to a public health laboratory.
- Blood cultures are recommended if the patient is febrile, has hemorrhagic bullae, or has signs of sepsis.
- Necrotic tissue should be debrided; severe cases may require fasciotomy or limb amputation.
- Antibiotic therapy:
- Doxycycline (100mg oral/IV twice a day for 7–14 days) and a third-generation cephalosporin (e.g., ceftazidime 1–2g IV/IM every 8 hours) is generally recommended.
- A single-agent regimen with a fluoroquinolone such as levofloxacin, ciprofloxacin, or gatifloxacin has been reported to be at least as effective in an animal model as a regimen with doxycycline and a cephalosporin.
- Doxycycline and fluoroquinolones are sometimes contraindicated in children. Treat children with trimethoprim-sulfamethoxazole plus an aminoglycoside.
Early fasciotomy within 24 hours after development of clinical symptoms can be life saving in patients with necrotizing fasciitis.
Early debridement of the infected wound has an important role in successful therapy and is especially indicated to avoid amputation of fingers, toes, or limbs.
Expeditious and serial surgical evaluation and intervention are required because patients may deteriorate rapidly, especially those with necrotizing fasciitis or compartment syndrome.
Reconstructive surgery, such as skin graft, is indicated in the recovery phase.
Vibriosis prognosis is excellent in immunocompetent patients who have acute Vibrio gastroenteritis.
In patients with Vibrio wound infection or septicemia, the prognosis is very grave 2 and depends on the following:
- Underlying medical conditions such as cirrhosis or leukemia
- Pathogen (Vibrio vulnificus infection is associated with a 50% mortality rate.)
- Prompt initiation of effective antibiotic therapy
- Early fasciotomy and debridement
- Availability of intensive monitoring and medical care for serious complications
- Availability of reconstructive surgery and physical rehabilitation
- Vibrio Species Causing Vibriosis. https://www.cdc.gov/vibrio
- Miyoshi S, Nakazawa H, Kawata K, Tomochika K, Tobe K, Shinoda S. Characterization of the hemorrhagic reaction caused by Vibrio vulnificus metalloprotease, a member of the thermolysin family. Infect Immun. 1998 Oct. 66(10):4851-5.