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What Are Vibrio bacteria?

Vibrios are bacteria that occur naturally in estuarine and marine waters worldwide. Vibrio are in the same family of bacteria that cause cholera. There are over 80 species of Vibrio bacteria. Vibrio vulnificus, Vibrio parahaemolyticus, Vibrio fluvialis, Vibrio mimicus, and Vibrio alginolyticus are some of the species known to cause infection when people are exposed by open wounds or punctures that occur while swimming, wading, crabbing, or fishing. Not all strains of Vibrios cause human illness. Vibrio

Vibrios are naturally-occurring bacteria, and pollution is not considered a factor for finding these bacteria in surface waters. The most significant factors for finding them in surface waters are temperature, salinity (a measure of how much salt is in the water), and chlorophyll. Vibrio bacteria are not commonly found in the winter when water temperatures are low, but may be common in the summer and early fall when water temperatures are warm.

Since Vibrios can be naturally found in warm estuarine and marine waters, people with open wounds may be exposed to Vibrio through direct contact with the water.  When open wounds are exposed to warm seawater with Vibrio, a skin infection may result; these infections may lead to skin breakdown and ulcers. People with weakened immune systems are at higher risk for very serious life threatening illness from V. vulnificus. Though rare, cases do occur sporadically. Anyone who suspects this type of infection following contact with marine or estuarine waters should see a doctor as soon as possible.

How Can You Prevent Vibrio Infection?
The only way to prevent infection is to avoid contact with the water. However, the incidence of infection from swimming and other recreational activities in Maryland waters is relatively rare. 

When water contact cannot be avoided:

  • Cover wounds with water proof bandages
  • Carry hand sanitizer to swimming areas and when fishing or crabbing so that wounds that occur can be cleansed immediately or have ready access to soap and water
  • Wear water shoes to avoid cuts and scrapes
  • Always shower following swimming in natural waters and wash hands before handling food or eating. 

CDC provides more information on Vibrio vulnificus and Vibrio parahaemolyticus.

MDE has created fact sheets about Vibrio for Citizens and Health Providers.

Maryland Department of Health & Mental Hygiene provides a fact sheet on Vibriosis (Non-cholera).

When are levels of Vibrio elevated in the Chesapeake and Coastal Bays?
Scientists with the National Oceanic & Atmospheric Administration have developed two models that can predict the likelihood of V.vulnificus and V. parahaemolyticus in the Chesapeake Bay. They have found that the environmental conditions that are most associated with levels of V. vulnificus and V. parahaemolyticus are water temperature, salinity, and chlorophyll. This experimental model is an example of how knowledge gained through Vibrio research is being used by scientists. 

The models include all strains of V. vulnificus and V. parahaemolyticus – those that can cause human illness and those that do not. They are designed to show when the likelihood of the presence of these bacteria may be relatively high in the Chesapeake Bay. The 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. Due to the complexity between exposure, dose, and an individual’s vulnerability for infections, there is no known threshold or standard that determines risk of infection from Vibrios. Rather, the models illustrate that the seasonal precautions people can take to prevent infection are very important to avoid or reduce the risk of infection. Below is a link to the experimental models developed by the National Oceanic & Atmospheric Administration National Centers for Coastal Ocean Science (NOAA/NCCOS/ Oxford Lab) that illustrate the association between Vibrios and water temperature, salinity, chlorophyll, and other factors. 

Link to NOAA website: http://chbr.noaa.gov/oxfordlab/pathogen_monitoring.aspx


© 2008 Maryland Department of the Environment and Maryland Department of Health and Mental Hygiene
Maryland Department of the Environment / Maryland Department of Health & Mental Hygiene / US Environmental Protection Agency