Vibrio vulnificus

Clinical Features

Wound or soft tissue infections. In persons with underlying medical conditions, especially liver disease, can cause bloodstream infections characterized by fever, chills, decreased blood pressure, blistering skin lesions, and often, death. In otherwise healthy persons, causes diarrhea, vomiting, and abdominal pain.

Etiologic Agent

Vibrio vulnificus, a halophilic (salt-requiring) gram-negative bacterium naturally and commonly found in marine and estuarine environments.

Incidence

An average of 50 culture-confirmed cases, 45 hospitalizations, and 16 deaths are reported each year from the Gulf Coast region (reporting states are Alabama, Florida, Louisiana, Mississippi, and Texas). Nationwide, there are as many as 95 cases (half of which are culture confirmed), 85 hospitalizations, and 35 deaths.

Sequelae

Bloodstream infections in persons with liver disease are fatal approximately 50% of the time. Persons who recover suffer no long-term consequences.

Transmission

Eating raw or undercooked shellfish, particularly oysters harvested from warmer waters. Wound infections may occur when wounds or soft tissues are exposed to warm seawater.

Risk Groups

All persons. Persons with underlying medical conditions, especially liver disease, may be at increased risk of infection and serious complications.

Surveillance

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. vulnificus  and other Vibrio spp. became nationally notifiable.  Thirty-three states have now implemented this reporting to state public health officials and CDC.

Trends

Infections are seasonal; over 85% occur between May and October. Environmental factors, such as warm water and moderate salinity, can increase the number of V. vulnificus organisms in shellfish.

Challenges

Many persons prefer to consume oysters and other shellfish raw. Many persons with liver disease are unaware of the hazards of raw oyster consumption and exposure to warm seawater.

Opportunities

Education focusing on the risks associated with consumption of raw and undercooked shellfish, especially in warm months. Implement refrigeration from harvesting to consumption. Timely reporting of V. vulnificus infections. Revision of the standards used for closing and re-opening of oyster beds to take into account the role of environmental factors.