The Connecticut Department of Agriculture’s Bureau of Aquaculture routinely monitors oyster harvest areas statewide for vibrio levels during the summer months. Samples are screened for levels of total vibrio bacteria and then vibrio vulnificus and pathogenic Vibrio parahaemolyticus levels. The bureau’s laboratory will have updated results on Friday, August 4, of Vibrio, both vibrio parahaemolyticus and vibrio vulnificus, from harvest areas statewide.
Since 2014, Connecticut has implemented Vibrio control plans for oyster harvest, which includes:
- In high-risk areas rapid cooling is required. Harvested oysters are immediately placed in an ice slurry, which drops the internal temperature to <50F within 3 hours of harvest. However, this process typically takes less than 20 minutes.
- In lower risk areas, harvesters are required to refrigerate, or ice, all oysters within 5 hours of harvest. Under this control plan, oysters must be <50F within 5 hours of refrigeration/icing. However, most harvesters choose to rapidly cool oysters statewide.
- ALL harvesters are required to shade oysters while on vessel.
Since the implementation of these controls Connecticut has not experienced an outbreak of Vibrio parahaemolyticus.
All certified Connecticut shellfish dealers are required to implement Vibrio time-to-temperature controls, which have been successful in preventing Vibrio outbreaks since implementation in 2014.
Vibrio vulnificus can cause severe infections when in contact with saltwater, brackish waters or contact with raw or undercooked shellfish. No Connecticut shellfish have ever been associated with Vibrio vulnificus illnesses.
- Two of the three Vibrio vulnificus infections reported to CT DPH in 2023 were wound infections not associated with seafood. The third infection was a CT resident that consumed raw oysters not harvested from Long Island Sound at an out-of-state establishment. Additional information about Vibrio controls can be found on the Department of Agriculture’s website.
