The Massachusetts Department of Public Health (DPH) and the Massachusetts Department of Fish and Game’s Division of Marine Fisheries (DMF) today announced a 14-day closure of oyster beds located in Duxbury Bay, Kingston Bay, Bluefish River, Back River, and Plymouth Harbor. This closure is due to two additional confirmed illnesses traced to oysters harvested from the area. A total of six cases of Vibrio parahaemolyticus (Vibrio) have now been linked to consumption of oysters harvested from these waters within a 30-day period. This number of illnesses triggers a federally mandated 14-day closure under the U.S. Food and Drug Administration/National Shellfish Sanitation Program’s Model Ordinance. A 7-day precautionary closure of the area was announced last week.

Vibrio parahaemolyticus/CDC
Vibrio parahaemolyticus/CDC

Harvesting and possession of oysters from these areas for commercial purposes is prohibited for a total of 14 days in harvest areas CCB-42, CCB-43, CCB-45, CCB-46, and CCB-47, inclusive of the days accrued during the existing 7-day precautionary closure. Commercial oyster beds are scheduled to reopen at sunrise on October 8, 2015. If 10 or more confirmed Vibrio illnesses are linked to oysters harvested from an area within a 30-day period, the FDA-enforced closure would be extended to 21 days.

Vibrio is a bacteria that thrives in warmer temperatures, multiplying as water and ambient air temperatures increase. The more Vibrio present in oysters, the greater the risk of infection. Current water temperatures in Duxbury Bay are consistent with water temperatures and environmental conditions that have been associated with Vibrio illnesses.

DPH and DMF have successfully partnered with industry to develop controls to mitigate risk of Vibrio associated with Massachusetts harvested oysters. A statewide Vibrio Control Plan has been in effect since 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.