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Information About Vibrio Bacteria



Vibrio are bacteria that occur naturally in brackish waters such as the Delaware Bay, the Inland Bays and tributaries, especially during warm weather months. Vibrio infections are relatively rare in Delaware and nationwide. However, when Vibrio or other bacteria come into contact with an open wound, they can cause serious infections. Vibrio infections can be particularly dangerous for people with weakened immune systems.

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Delaware Shellfish and Recreational Water Programs 302-739-9939

What You Can Do To Protect Yourself

Avoid water contact if you have any skin wounds.

If water contact cannot be avoided, cover wounds with waterproof bandages.

Wear water shoes to avoid cuts and scrapes.

Wear gloves or use extra care when handling crab pots or other equipment.

If you get a cut or a scrape, clean it immediately with soap and clean water after contact. If soap and clean water are not available, clean the wound with hand sanitizer then wash as soon as possible.

Always shower after swimming in natural waters and wash hands before handling food or eating.

If you have been in the water and develop a wound with unusual redness, swelling or drainage, seek medical attention immediately, and let your health care provider know whether you came in contact with brackish or salt water. 

Does Delaware Monitor For Vibrio?

No. There is no known numerical threshold or standard that can be linked to risk of infection from Vibrio bacteria. Therefore, monitoring Vibrio levels in Delaware waters would not result in information that could be used in issuing swimming advisories.

There are at least 80 different species and many different strains of Vibrio bacteria. Not all of them can make people sick.


Learn More About Vibrio Bacteria and Vibrio Illness (Vibriosis) in Delaware

Delaware Department of Health and Social Services fact sheet on Vibriosis

Centers for Disease Control Vibriosis Page

NOAA Vibrio Guidance

NOAA Shellfish Guidance for the Delaware Bay


An individual’s existing health condition and related vulnerability to infection may vary and are significant factors, making it too difficult to determine a risk standard.

Scientists have observed that Vibrio levels are high when water temperature exceeds 60 degrees. There is also a relationship between Vibrio levels and levels of salinity and chlorophyll.

While scientists have developed models to predict the presence of Vibrio in marine and estuarine waters, these models cannot determine individual risk for Vibrio-related illness and should not be viewed with this expectation or used to guide decisions about swimming or other activities in Delaware waters.

Since there is no action level that identifies risk of illness, it is recommended that you protect yourself when Vibrio levels may be high, which occur at such times as when water temperatures are warm. Know and follow the protective recommendations listed above.




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