Connecticut Department of Agriculture

Important Vibrio Information - Updated 8/18/2023

Vibrio bacteria naturally occur in coastal waters and are more abundant during the summer as the water warms. There are multiple Vibrio species that can cause human illness, but the most talked about currently in CT is Vibrio vulnificus. Vibrio vulnificus can cause severe infections when open cuts and wounds, including recent surgeries, piercings, and tattooed skin, are exposed to water containing the bacteria. In severe cases, Vibrio vulnificus wound infections can result in limb amputation, sepsis (blood infection), necrotizing fasciitis (tissue death), and death. Following CDC guidelines can prevent Vibrio vulnificus wound infections.

Connecticut shellfish have never been associated with Vibrio vulnificus infections. 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. Two of these individuals have, unfortunately, died. Additionally, an individual in Suffolk County, New York, has died from a Vibrio vulnificus wound infection in 2023.

Vibrio are being referred to in the media as “shellfish bacteria;” however, these bacteria are naturally occurring in the salt and brackish water. Shellfish can accumulate any contaminants, including bacteria, that are present in the water, which is why they are a highly regulated food commodity. The Department of Agriculture, Bureau of Aquaculture (DoAG) is responsible for ensuring all CT shellfish growing waters meet the national standards and that CT shellfish in interstate commerce are free of pathogens. As required by DoAG, all commercial harvesters implement Vibrio controls that include rapidly cooling the shellfish while on harvest vessels from June-September, when Vibrio are more prevalent in the water (learn more information on the State's Vibrio controls).

From July-September, the DoAG tests Vibrio levels in commercial shellfish from statewide locations each month as part of the routine monitoring program. The DoAG laboratory uses an FDA-approved DNA-detection method to monitor for two Vibrio species, Vibrio parahaemolyticus and Vibrio vulnificus (learn more about the Bureau of Aquaculture Laboratory Services). The DoAG lab has been analyzing samples for Vibrio parahaemolyticus since 2013, and Vibrio vulnificus since 2022. The Vibrio vulnificus testing was added to the DoAG lab’s platform in 2022, partly in response to the five Vibrio vulnificus wound infections that occurred in 2020. While Vibrio vulnificus is present in Long Island Sound, it has not been detected in CT shellfish. The routine Vibrio parahaemolyticus monitoring, annual Vibrio control plans, and illness investigations conducted nation-wide have demonstrated that CT has not had a Vibrio outbreak since the control plans were established in 2014. The most recent testing was conducted by the DoAG on 8/1/23 with results on 8/3/23.

Questions regarding Vibrio vulnificus wound infections should be directed to the CT Department of Public Health. Questions regarding bathing beaches should be directed to CT DEEP Beach Monitoring.