| Clinical
Features |
Watery diarrhea, often with abdominal
cramping, nausea, vomiting, and fever. Less commonly, wound
or soft tissue infections. Occasionally bloodstream infections.
|
| Etiologic
Agent |
Vibrio parahaemolyticus,
a halophilic (salt-requiring) gram- negative bacterium naturally
and commonly found in warm marine and estuarine environments.
|
| Incidence |
Nationwide, an average of 190 culture-confirmed
cases, 30 hospitalizations, and 1-2 deaths are reported each
year. However, it is estimated that there are truly as many
as 3000 cases (most not culture confirmed), 40 hospitalizations
and 7 deaths. |
| Sequelae |
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. |
| Transmission |
Eating raw or undercooked shellfish,
particularly oysters. Less commonly, wound infections may
occur when wounds or soft tissues are exposed to warm seawater.
|
| Risk
Groups |
All persons. Persons with underlying
medical conditions, such as alcoholism and liver disease may
be at increased risk of infection and serious complications. |
| Surveillance |
Twenty states require reporting
of Vibrio infections to public health officials. Surveillance
for culture-confirmed 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. |
| Trends |
Infections are seasonal; approximately
70% occur between May and October. Four outbreaks linked to
the consumption of raw oysters occurred in 1997 and 1998 involving
over 700 cases combined. Environmental factors, such as warm
water and moderate salinity, can increase the number of V.
parahaemolyticus organisms in shellfish. |
| Challenges |
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. |
| Opportunities |
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. |
|
December 2003
|
