Raw is risky: Searching for answers behind Vibrio-in-raw-oyster outbreaks

Michael Casey of The Charlotte Observer reports that for the past 25 years, researcher Stephen Jones has tried to understand the threat that bacteria may pose to oysters in New Hampshire’s Great Bay estuary. He often couldn’t get funding to study the problem. But that is beginning to change as scientists notice “something is going on.”

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]

Scientists are recognizing that a waterborne disease sickening tens of thousands of people each year is associated with warmer waters of the Gulf of Mexico moving northward, partly due to climate change. The problem is extremely rare in New Hampshire and neighboring Maine, but scientists have seen cases elsewhere in New England and expect it to become a bigger problem.

Cases of human illness have been piling up since Sept. in Florida, Massachusetts and Western Canada.

“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, of the Northeast Center for Vibrio Disease and Ecology at the University of New Hampshire. “In the last 10 or 20 years, it’s become very apparent that there is something going on.”

In a paper in the science journal PLOS One, Jones and other scientists reported their findings that illnesses from vibrio bacteria have jumped significantly in New England — from five cases in 2000 to 147 in 2013. Disease-causing bacteria can contaminate oysters, leading to infections such as diarrhea, vomiting and abdominal pain.

Jones and his colleague, Cheryl Whistler, concluded that warmer waters in the Great Bay, higher salinity and the presence of chlorophyll all contributed to higher concentrations of one of the more common vibrio species that makes people sick — vibrio parahaemolyticus. The researchers are hoping their findings will serve as the foundation of an early warning system for the region’s booming oyster industry.

oysters-grillCurrently, all experts can do is monitor the waters and rapidly cool harvested oyster to halt bacteria growth.

An August report in the Proceedings of the National Academy of Sciences found that warming waters were linked to waterborne food poisoning, especially from eating raw oysters.

“There is similar reporting in Alaska where it has been found that increased cases have been occurring where it has not been reported before because of the temperature rise,” said the study’s lead author, Rita Colwell, of the University of Maryland.

The industry has welcomed Jones and Whistler’s work, noting that outbreaks like the one that occurred last month in Massachusetts need to be avoided. Nearly 75 people were sickened.

“When you are involved with a recall because people have gotten sick, you are a losing tremendous amount of money and a tremendous amount of credibility,” said Tom Howell, president of Spinney Creek Shellfish Inc., in Eliot, Maine, which harvests oysters from the Great Bay. A predictive model would allow the industry to move more aggressively to avoid an outbreak, he said.

But Howell and Chris Nash, New Hampshire’s shellfish program manager, said that day could be far off.

“We are still learning what seems to trigger these pathogenic strains to multiply … We don’t have that knowledge yet and it may be that we never do,” Nash said. “We are talking about biological organisms … They react to their environment different, the same way humans do.”

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.

Climate change to drive up NZ Salmonella risk

Increasing temperatures caused by climate change are expected to bump up New Zealanders’ likelihood of getting sick with Salmonella, according to new findings from Kiwi scientists.

crisis.what.crisisUsing current climate projections for Auckland, Christchurch and Wellington, the researchers calculated inhabitants’ future risk of getting salmonella. They found that Aucklanders will be the most likely to get sick followed by Cantabrians, whereas Wellingtonians won’t see much of a difference.

 Australian and New Zealand Journal of Public Health

Objective: Modelling the relationship between weather, climate and infectious diseases can help identify high-risk periods and provide understanding of the determinants of longer-term trends. We provide a detailed examination of the non-linear and delayed association between temperature and salmonellosis in three New Zealand cities (Auckland, Wellington and Christchurch). 
Methods: Salmonella notifications were geocoded to the city of residence for the reported case. City-specific associations between weekly maximum temperature and the onset date for reported salmonella infections (1997–2007) were modelled using non-linear distributed lag models, while controlling for season and long-term trends. 
Results: Relatively high temperatures were positively associated with infection risk in Auckland (n=3,073) and Christchurch (n=880), although the former showed evidence of a more immediate relationship with exposure to high temperatures. There was no significant association between temperature and salmonellosis risk in Wellington.
Conclusions: Projected increases in temperature with climate change may have localised health impacts, suggesting that preventative measures will need to be region-specific. This evidence contributes to the increasing concern over the public health impacts of climate change.