Get the facts on Vibrio

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Vibrio are bacteria that occur naturally in brackish water such as the Chesapeake Bay and its tributaries, and in salt water, especially during warm weather months. Vibrio infections are relatively rare in Maryland 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 liver disease or weakened immune systems.

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 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. 

Are Vibrio levels monitored in Maryland to provide guidance for swimming and other water contact?

No. There is no known numerical threshold or standard that can be linked to risk of infection from Vibrio bacteria.

  • There are at least 80 different species and many different strains of Vibrio bacteria. Not all of them can make people sick.
  • 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 the Chesapeake Bay.
  • Since there is no action level that identifies risk of illness, it is recommended that you protect yourself whenever Vibrio levels may be high, such as when water temperatures are warm. Know and follow the recommendations listed above.

 Learn more about Vibrio bacteria and Vibrio illness


 Vibrio flyers


Centers for Disease Control and Prevention

Contact Information

 Please direct questions or comments concerning this page to (410) 537-3818.​


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