Disease-causing and harmless forms of Vibrio parahaemolyticus bacteria exist naturally in marine and estuarine environments throughout the world, including the coastal waters of the United States and Canada. The bacteria are capable of infecting marine fish and shellfish, especially oysters harvested from coastal areas.
Vibrio parahaemolyticus is transmitted mainly via the consumption of infected/contaminated raw and improperly cooked, or cooked and then re-contaminated fish and shellfish. A higher risk of transmission has been linked to the warmer months of the year when the bacteria, which reside in marine silt during the cooler months, live freely in the water and within fish and seafood. Person-to-person transmission is rare and is fecal-oral in nature.
On rare occasions the bacteria are also capable of causing wound infections, which can occur either through the exposure of a new wound caused by an immediate injury or pre- existing wound to brackish, estuarine or marine waters. An infection can also occur if the wound is exposed to raw fish or shellfish, or their drippings.
Illness onset can occur between 4 to 96 hours after exposure. The intestinal presentation of the illness is typically moderate in severity and resolves within 1-7 days.
- Watery diarrhea
- Nausea and vomiting
- Abdominal cramps
- Fever and headache
Severe symptoms occur in a quarter of those affected and include:
- Dysentery-like illness
- Bloody or mucoid diarrhea
- High fever
- Elevated white blood cell count
- Rarely - Systemic infection and death
Severe illness is more common in individuals with weakened immune systems.