A recent study may be the first one to link a warming trend in sea surface temperatures to the spread of vibrios and the human diseases which can be caused by pathogenic strains. “In this study, for the first time to our knowledge, experimental evidence is provided on the link between multidecadal climatic variability in the temperate North Atlantic and the presence and spread of an important group of marine prokaryotes, the vibrios, which are responsible for several infections in both humans and animals,” the researchers wrote in the study, which was published earlier this month in the Proceedings of the National Academy of Sciences. http://www.dreamstime.com/royalty-free-stock-photography-raw-oysters-image23648417People can be exposed to vibrio illnesses by eating raw oysters or other raw or undercooked seafood, or by drinking or swimming in contaminated water. The incidence of such illnesses has been increasing during the past 20 years. According to the U.S. Centers for Disease Control and Prevention (CDC), there are about a dozen species of vibrio known to cause illness in humans. The most common are V. parahaemolyticus, V. vulnificus, and V. alginolyticus. The ones that cause the illness known as vibriosis live naturally in brackish or salt water, and those who contract vibriosis become infected by consuming raw or undercooked seafood or exposing a wound to seawater. Most infections occur from May through October when water temperatures are warmer, according to CDC. About 100 deaths per year on average can be blamed on vibrio. The agency also reports that U.S. vibrio infections have gone from an average of about 390 lab-confirmed cases per year in the late 1990s to about 1,030 annually on average in recent years. Lead study author Rita Colwell of the University of Maryland told ABC News that the confirmed case numbers show “a remarkable increase on an annual basis.” She noted that Alaska, where sea water is generally colder and therefore less hospitable to vibrio bacteria, has been getting cases after people there ate infected oysters. The researchers used DNA and a 50-year database of reports on plankton, water temperatures and diseases to put together a comprehensive picture of the relationship between global warming and increasing vibrio illnesses. “Now we have linked very directly the increase and the trend in number of cases, so it’s all coming together in great detail,” Colwell said. CDC advises people not to eat raw or undercooked oysters or other shellfish, but to cook them before eating. Other tips from the agency to reduce the chances of vibrio infection include:

  • Always wash your hands with soap and water after handing raw shellfish.
  • Avoid contaminating cooked shellfish with raw shellfish and its juices.
  • Stay out of brackish or salt water if you have a wound (including cuts and scrapes), or cover your wound with a waterproof bandage if there’s a possibility it could come into contact with brackish or salt water, raw seafood, or raw seafood juices.
  • Wash wounds and cuts thoroughly with soap and water if they have been exposed to seawater or raw seafood or its juices.
  • If you develop a skin infection, tell your medical provider if your skin has come into contact with brackish or salt water, raw seafood, or raw seafood juices.

(To sign up for a free subscription to Food Safety News, click here.)