As summer continues and Chesapeake Bay waters remain warm, we’re reminding residents to take simple precautions to protect themselves from Vibrio bacteria.
Vibrio bacteria occur naturally in brackish waters like the Chesapeake Bay and its tributaries, as well as in salt water, particularly during the warmer months. While Vibrio infections remain relatively uncommon in Maryland, case numbers have been on the rise over the last few decades and health experts are encouraging people to be aware of the risks—especially when swimming, fishing, crabbing, boating, or working in and around the water.
Why the Reminder?
According to recent reporting and Maryland health officials, warming Chesapeake Bay waters are creating favorable conditions for Vibrio bacteria to thrive. Scientists have observed that Vibrio levels tend to increase when water temperatures rise above approximately 60°F, and the bacteria may remain present for a longer portion of the year as waters stay warmer.
Although infections are still rare, they can become very serious if bacteria enter the body through an open wound.
Who Is Most at Risk?
Anyone can develop a Vibrio infection, but the risk of severe illness is higher for people who:
- Have liver disease
- Have diabetes
- Have a weakened immune system
- Have certain chronic medical conditions
People in these groups should take extra precautions when entering brackish or salt water.
How Infection Happens
Vibrio bacteria can enter the body when an open cut, scrape, or wound comes into contact with contaminated water. Less commonly, some Vibrio illnesses are associated with eating raw or undercooked shellfish, particularly oysters.
Early treatment is important because some wound infections can progress rapidly.
Protect Yourself
If you’re spending time on or near the Chesapeake Bay or its tributaries:
- Avoid entering the water if you have open cuts, scrapes, or wounds.
- If water contact cannot be avoided, cover wounds with a waterproof bandage.
- Wear water shoes to help prevent cuts and scrapes.
- Wear gloves or use extra care when handling crab pots, fishing gear, or other equipment.
- If you receive a cut or scrape while in or around the water, wash it immediately with soap and clean water. If soap and water aren’t available, use hand sanitizer until you can wash the wound thoroughly.
- Shower after swimming in natural bodies of water and wash your hands before eating or preparing food.
Know When to Seek Medical Care
If you develop a wound that becomes:
- Increasingly red
- Swollen
- Painful
- Draining fluid
Seek medical attention immediately and tell your healthcare provider that the wound was exposed to brackish or salt water. Prompt treatment can be critical.
Why Doesn’t Maryland Monitor Vibrio Like Beach Water Quality?
Unlike bacteria used to determine beach closures, there is no established Vibrio level that predicts when the water is safe or unsafe.
There are more than 80 species of Vibrio, and not all cause illness. An individual’s health status, the specific bacteria present, water temperature, salinity, and other environmental conditions all influence risk. While researchers can model where Vibrio is more likely to occur, those models cannot predict an individual’s risk of infection and are not intended to guide decisions about swimming or other recreational activities.
Because there is no action threshold for Vibrio, the best approach is to practice preventive measures whenever Bay waters are warm.
Learn More
For additional information about Vibrio bacteria and water safety, visit:
- Maryland Department of the Environment – Get the Facts on Vibrio
- Maryland Department of Health – Vibrio
- Centers for Disease Control and Prevention (CDC) – Vibrio Illness (Vibriosis)
Enjoy Maryland’s waterways this summer—but remember that a few simple precautions can help protect you and your family while enjoying everything the Chesapeake Bay has to offer.