A study published in Proceedings of the National Academy of Sciences has found that climate change is increasing the incidence of Vibrio infections in the United States. Long term ecological data analysis has found that climate change is affecting marine animal, plant, and fungi populations.
Marine prokaryotes (single celled organisms), the largest living biomass in the world’s oceans, play a fundamental role in maintaining life on the planet. Evidence has been found that, for the first time, provides a link between climate variability in the North Atlantic and the presence and spread of marine Vibrios, one of the ocean’s prokaryotes. Several species of Vibrio bacteria are responsible for infections in animals and humans.
Humans acquire Vibrio infections by eating raw or undercooked oysters or other seafood, or by swimming in contaminated water or by drinking that water. Some of the species of Vibrio that cause illness, V. vulnificus, V. alginolyticus, and V. parahaemolyticus, live in salt water and brackish water and live in plankton. Another type of Vibrio bacteria, V. cholerae, causes cholera.
The scientists used archived plankton samples collected by the Continuous Plankton Recorder survey from 1958 to 2011 and assessed the abundance of vibrios, including those that are pathogenic to people, in nine areas of the North Atlantic and the North Sea. There was a correlation with climate change and plankton number changes.
Plankton nourish Vibrio species, then oysters and other shellfish ingest the plankton and become contaminated. When people eat raw oysters or oysters that are not thoroughly cooked, they can become ill.
The study states that “long term increase in Vibrio abundance is promoted by increasing sea surface temperature (up to about 1.5°C in the past 43 years) and is positively correlated with the North Hemispheric Temperature and Atlantic Multidecadal Oscillation climate indices.” The actual number of Vibrio bacteria were not measured in the study, but its relative abundance of Vibrio levels in plankton was measured.
There has been an “unprecedented occurrence” of environmentally acquired Vibrio infections in the human population of Northern Europe and the Atlantic Coast of the U.S. in recent years, according to the study. In fact, Vibrio has been found in oysters harvested in the cold waters off Alaska, which is unprecedented.
Lab-confirmed Vibrio infections in the U.S. have increased from about 390 a year on average in the late 1990s to 1,030 recently. And most cases aren’t confirmed and reported to authorities, so those numbers are most likely much higher. About 100 people die from Vibrio infections in the United States every year. Most Vibrio cases occur in the warmer months from May through October.
To avoid acquiring a Vibrio infection, pay attention to warnings that are posted on various government websites about Vibrio in the water where you may swim or harvest shellfish. Don’t eat raw or undercooked shellfish. Wash your hands with soap and water after you handle raw shellfish, and keep raw seafood away from cooked shellfish and other foods that are eaten raw.
Don’t swim in areas that are under Vibrio warnings. If you do swim in salt water, stay out of the water if you have a wound. Wash any cut or wound with soap and water if exposed to sea water. And if you do develop a skin infection after being in contact with raw shellfish or swimming in salt or brackish water, see a doctor.