Fish and seafood harvested from seawater can be contaminated with Vibrio species bacteria, natural inhabitants of the marine environment. The two species with the greatest national public health concern are Vibrio parahaemolyticus and Vibrio vulnificus. Vibrio cholera, along with these two species, are pathogens of public health concern in other areas of the world. Fortunately, the bacteria are destroyed with heat, so thoroughly cooking seafood is effective at controlling these pathogens in food. Eating raw or undercooked seafood, or contaminating other food preparation surfaces or foods are risk factors for infection and progression to foodborne illness.
Symptoms of illness
Symptoms of Vibrio parahaemolyticus infection are diarrhea, abdominal cramps, nausea, vomiting, headaches, fever, and chills. The infection is usually mild and will resolve without medical treatment in 2–3 days. Vibrio vulnificus infection in healthy individuals resembles Vibrio parahaemolyticus infection. Vibrio vulnificus infection in immune-compromised persons, especially those with chronic liver disease, is very serious and is often fatal. Following initial infection, symptoms will progress to bacteremia (bacteria in the bloodstream), septic shock, and blistering skin lesions. If Vibrio vulnificus infection is suspected, treatment should be sought immediately, as antibiotic therapy has been shown to increase survival rates.
Public health consequences
The exact number of Vibrio species cases that occur each year is hard to determine because many people attribute their illness to a virus or flu. The local Health Department and Centers for Disease Control and Prevention (CDC) cannot record the number of cases accurately unless the ill person seeks medical care, which is unusual in mild cases. As of 2007, diagnosed infections with Vibrio bacteria are required to be reported to the CDC in order to help monitor trends in the disease. The CDC has calculated an estimate of the number of cases of vibriosis based on corrections for underreporting, misdiagnosis, and the number of cases that are not caused by contaminated food.
The CDC estimates that there are almost 35,000 cases of Vibrio parahaemolyticus (86% foodborne); 22.5% cases will result in hospitalization with 4 fatalities estimated. The more severe, but fortunately less common, Vibrio vulnificus will cause an estimated 96 cases (47% foodborne) each year in the United States. Most cases (91%) will require hospitalization and 36 cases will be fatal.
The age group that has the most severe illnesses requiring hospitalization, and perhaps causing death, is the elderly over the age of 60 years (0.8 cases/100,000 population), but anyone of any age group who is immune-compromised, especially by chronic liver disease, is susceptible. The elderly are susceptible because of aging and also because of the increased incidence of other chronic diseases that affect the immune system.
Infection with Vibrio species bacteria is mostly associated with consumption of seafood, especially raw oysters, or undercooked seafood. Contamination of these filter-feeding shellfish often occurs during the warmer months, May through October. Contamination of cooked seafood could occur if combined with raw or undercooked seafood or the containers used to store the raw seafood are then used to store the cooked product. Non-food infections usually occur because of open-wound contact with contaminated seawater or contaminated seafood products.
How to control this pathogen in your home
1. Avoid eating raw or undercooked seafood.
- Obtain shellfish from approved sources.
- Keep cooked seafood from contact with unheated seawater or unwashed storage containers used for the raw product.
- Keep seafood refrigerated at all times.
2. Knives, cutting boards, and food preparation surfaces should be washed with hot water and soap after contact with raw seafood.
- Clean sinks and counters with paper towels or clean cloths and hot soapy water before and after cooking food.
- Keep foods that are ready to eat away from raw seafood.
- Wash knives, cutting boards, and counters with hot water and soap after you work with raw seafood.
- Scrub your cutting board with dish soap. If your cutting board is not made of wood, you can put it into the dishwasher.
- Wash your hands with soap and warm water after working with raw seafood.
- Put thawing seafood in a dish in the refrigerator to keep juices from leaking onto the food below.
3. Wash hands with warm, soapy water before and after handling raw foods.
- First, wet your hands.
- Add soap to your hands.
- Rub both sides for at least 20 seconds.
- Rinse thoroughly.
- Air dry, or dry your hands with a clean towel or paper towel.
- Always wash your hands after using the toilet, after changing a baby's diaper, after touching pets or other animals, and after sneezing or coughing.
Centers for Disease Control and Prevention. Vibrio parahaemolyticus. cdc.gov/nczved/divisions/dfbmd/diseases/vibriop/. Accessed: August 8, 2011.
Centers for Disease Control and Prevention. Vibrio vulnificus. cdc.gov/nczved/divisions/dfbmd/diseases/vibriov/. Accessed: August 8, 2011.
Centers for Disease Control and Prevention. Vital signs: Incidence and trends of infection with pathogens transmitted commonly through food—foodborne diseases active surveillance network, 10 U.S. sites, 1996–2010. Morbidity and Mortality Weekly 2011; 60 (22):749–755.
Hillers, V.N., Medeiros, L.C., Kendall, P., Chen, G., & DiMascola, S. Consumer food handling behaviors associated with prevention of 13 foodborne illnesses. Journal of Food Protection 2003; 66:1893–1899.
Scallan, E., Hoekstra, R.M., Angulo, F.J., Tauxe, R.V., Widdowson, M.A., Roy, S.L., Jones, J.L., & Griffin, P.M. Foodborne illness acquired in the United States—major pathogens. Emerging Infectious Diseases 2011; 17:7–15.
U.S. Food and Drug Administration. Vibrio parahaemolyticus. The Bad Bug Book. fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm070452.htm. Accessed: February 11, 2010.