Watery diarrhea, often with abdominal cramping, nausea, vomiting, and fever. Less commonly, wound or soft tissue infections. Occasionally bloodstream infections.
Vibrio parahaemolyticus, a halophilic (salt-requiring) gram- negative bacterium naturally and commonly found in warm marine and estuarine environments.
Nationwide, an average of 215 culture-confirmed cases, 30 hospitalizations, and 1-2 deaths are reported each year. However, it is estimated that there are truly as many as 4500 cases (most not culture confirmed).
Most persons recover after 3 days and suffer no long-term consequences. Bloodstream infections and death are uncommon and usually occur in persons with underlying medical conditions.
Eating raw or undercooked shellfish, particularly oysters. Less commonly, wound infections may occur when wounds or soft tissues are exposed to warm seawater.
All persons. Persons with underlying medical conditions, such as alcoholism and liver disease may be at increased risk of infection and serious complications.
Surveillance for infections has been conducted in the Gulf Coast states of Alabama, Florida, Louisiana, Mississippi, and Texas since 1988, and expanded to include FoodNet sites in 1996. In January 2007, infections caused by V. parahaemolyticus and other Vibrio spp. became nationally notifiable. Thirty-three states have now implemented this reporting to state public health officials and CDC.
Infections are seasonal; approximately 70% occur between May and October when water temperatures are warmer. Large outbreaks linked to the consumption of raw oysters occurred in 1997, 1998, and 2006. Environmental factors, such as warm water and moderate salinity, can increase the number of V. parahaemolyticus organisms in shellfish.
Many persons prefer to consume oysters and other shellfish raw. Not all strains cause illness. Large outbreaks have occurred when counts of V. parahaemolyticus in oysters from implicated sites were very low. Therefore, monitoring and responding to elevated counts of V. parahaemolyticus in the harvesting waters and in shellfish does not adequately protect the public health.
Education focusing on the risks associated with consumption of raw and undercooked shellfish, especially in warm months. Implement refrigeration from harvesting to consumption. Revision of the standards used for closing and re-opening of oyster beds to take into account the role of environmental factors.