Raw is risky: Study links global warming to rise in waterborne illnesses

Rising global temperatures are clearly linked to increasing waterborne food poisoning, particularly from eating raw oysters, along with other nasty infections, a new study shows.

Oyster-Vancouver, B.C.- 07/05/07- Joe Fortes Oyster Specialist Oyster Bob Skinner samples a Fanny Bay oyster at the restuarant. Vancouver Coastal Health now requires restaurants to inform their patrons of the dangers of eating raw shellfish. (Richard Lam/Vancouver Sun) [PNG Merlin Archive]

About a dozen species of vibrio bacteria make people sick from eating raw or undercooked seafood or drinking or swimming in tainted water. It also causes cholera, although that was not the focus of the research.

Lab-confirmed vibrio infections in the United States have increased from an average of about 390 a year from the late 1990s to an average of 1,030 in recent years, according to the Centers for Disease Control and Prevention. But most cases aren’t confirmed by tests and reported.

“It’s a remarkable increase on an annual basis,” said study lead author Rita Colwell of the University of Maryland, a top microbiologist who used to head the National Science Foundation.

The study examined Europe and North America, but the most consistent tracking of vibrio illnesses were in the United States. The CDC blames about 100 deaths a year on vibrio on average.

Even Alaska, where such outbreaks used to be unheard of because the bacteria needs warm water, is getting cases from people eating vibrio-infected oysters, Colwell said. Her study, published in Monday’s Proceedings of the National Academy of Sciences , highlights an unprecedented wave of vibrio illnesses from swimming in northern Europe during heat waves in 1994, 1997, 2003, 2006 and 2010.

Climate influence on Vibrio and associated human diseases during the past half-century in the coastal North Atlantic

22.jun.16

DOI: 10.1073/pnas.1609157113

Vezzulli, C. Grande, P.C. Reid, P. Hélaouët, M. Edwards, M.G. Höfle, I. Brettar, R.R. Colwell, C. Pruzzo

http://www.pnas.org/content/early/2016/08/02/1609157113.abstract

Climate change is having a dramatic impact on marine animal and plant communities but little is known of its influence on marine prokaryotes, which represent the largest living biomass in the world oceans and play a fundamental role in maintaining life on our planet. 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. Using archived formalin-preserved plankton samples collected by the Continuous Plankton Recorder survey over the past half-century (1958–2011), we assessed retrospectively the relative abundance of vibrios, including human pathogens, in nine areas of the North Atlantic and North Sea and showed correlation with climate and plankton changes. Generalized additive models revealed that long-term increase in Vibrio abundance is promoted by increasing sea surface temperatures (up to ∼1.5 °C over the past 54 y) and is positively correlated with the Northern Hemisphere Temperature (NHT) and Atlantic Multidecadal Oscillation (AMO) climatic indices (P < 0.001). Such increases are associated with an unprecedented occurrence of environmentally acquired Vibrio infections in the human population of Northern Europe and the Atlantic coast of the United States in recent years.