The Massachusetts Department of Public Health (DPH) and the Massachusetts Department of Fish and Game, Division of Marine Fisheries (DMF) today announced the precautionary closure of oyster beds in Katama Bay in the community of Edgartown effective September 3, 2014. This precautionary closure is due to the presence of environmental conditions conducive to the growth of Vibrio parahaemolyticus (Vibrio) in oysters harvested from the area based on information relative to closures in 2013.

Harvesting and possession of oysters from these areas for commercial purposes is prohibited for seven days. This is the first time a specific harvest area in Massachusetts has been closed due to Vibrio this year. The decision to issue a precautionary closure was made jointly between DPH and DMF officials in response to warming waters in Katama Bay, anticipated high air temperatures forecast for this week, and identification of a fourth confirmed case of Vibrio tied to the area. Current water temperatures in Katama Bay are consistent with water temperatures and environmental conditions that were associated with Vibrio illnesses in 2013.

The Vibrio season in Massachusetts runs from May to October. Health officials are reminding all persons who are at high risk, especially those who are elderly or immune compromised, to avoid eating any raw shellfish.

This year, DPH has linked four cases of Vibrio illness to oysters consumed from the Katama Bay area.

Vibrio is a bacteria that occurs naturally in coastal waters in the United States and Canada. It has caused illnesses in the Gulf Coast and West Coast of the United States for a number of years. It is not related to pollution of Massachusetts shellfish.

When ingested, Vibrio causes watery diarrhea, often with abdominal cramping, nausea, vomiting, fever and chills. Usually these symptoms occur within 24 hours of ingestion and last three days. Severe illness, increased risk of infection, and serious complications, including death, may occur in the very young, elderly, pregnant women, and immune impaired individuals such as people with underlying medical issues, such as liver disease or alcoholism. About 10 percent of cases will develop a blood infection that may require hospitalization. Vibrio can also cause an infection of the skin when an open wound is exposed to warm seawater.