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article imageUNH researchers one step closer in predicting vibrio outbreaks

By Karen Graham     Dec 4, 2016 in Environment
Reports from state health departments in New England show that the annual number of reported human cases of vibriosis from eating oysters have increased in recent years. Researchers wanted to know why this is happening.
In the past decade, there has been a decided increase in the number of vibriosis cases in the New England area. This is unusual because the northeastern Atlantic is usually cooler than other climes and food-borne illnesses from eating raw seafood have not been a problem.
Stephen Jones has been doing research on the bacterial contamination of oysters in New Hampshire's Great Bay Estuary for the past 25 years, trying to understand the threat bacteria may pose to the shellfish. And for many years, it didn't appear to be a problem big enough to justify funding, but then things changed.
"We have this situation in the northern part of the United States and other cooler climates where people haven't thought this had been a problem," said Jones, who is with the Northeast Center for Vibrio Disease and Ecology at the University of New Hampshire.
In a study published in the journal PLOS One, Jones, his colleague Cheryl Whistler and other scientists detailed their findings that show illnesses from vibrio bacteria have increased significantly in New England in the past 10 to 20 years.
They also developed a predictive modeling tool for estimating the likelihood of Vibrio parahaemolyticus in coastal oysters in Great Bay Estuary. The model takes into account salinity, temperature and phytoplankton biomass.
The study found that the waters of Great bay Estuary have become warmer and have an increased salinity. These factors, along with chlorophyll have all contributed to higher concentrations of Vibrio parahaemolyticus, the more common of the vibrio species that make people sick.
The researchers are hoping that their findings will help in the creation of an "early warning system" for the region's oyster industry. As of the present time, about all the experts can do is monitor water conditions and use rapid cooling to stop the bacterial growth in harvested oysters.
"Eventually, we would want shellfish managers to have access to these models that would allow them to communicate to the growers that conditions have changed and that we now need this to manage the potential risk to reduce whether there will be exposures," Whistler said, according to ABC News.
The study's lead author, Rita Colwell, of the University of Maryland, cited the increase in the number of cases of vibriosis in Alaska, another area where ocean temperatures have been rising. And just last month, in Massachusetts, 75 people became ill with norovirus after eating raw oysters.
One hundred and four Vibrio parahaemolyticus isolates with the same DNA “fingerprint” were repor...
One hundred and four Vibrio parahaemolyticus isolates with the same DNA “fingerprint” were reported to PulseNet from persons in 13 states who became ill from May 12, 2013 through August 19, 2013. Of the 104 Vibrio parahaemolyticus isolates, 76 have been serotyped and all 76 were found to be serotype O4:K12.
CDC
Tom Howell, president of Spinney Creek Shellfish Inc., in Eliot, Maine harvests oysters from the Great Bay. He said, "When you are involved with a recall because people have gotten sick, you are losing a tremendous amount of money and a tremendous amount of credibility." He told CTV News Canada having a predictive model would allow the oyster industry to react more aggressively to outbreaks.
But the time when predictive modeling will prove useful may be a long way off. Warming ocean temperatures, along with other environmental factors, such as turbidity, suspended sediments, nutrients, and dissolved organic carbon also play a role in stimulating the growth of vibrio.
More about vibriosis, Oysters, Warming oceans, Great Bay Estuary, New hampshire