I’m not your guy, pal: Raw oysters risky for wine drinkers

When Canada’s food safety agency announced a recall of B.C. oysters last August, it meant producers like Steve Pocock had to ensure every last oyster they had shipped after a certain date was accounted for.

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]

Along with a recall – issued by the Canadian Food Inspection Agency (CFIA) after dozens of people got sick as a result of eating raw oysters contaminated with Vibrio parahaemolyticus – there was a ban on restaurants serving raw oysters from British Columbia.

The inconvenience and forgone sales added up to a big hit for Mr. Pocock and other producers in British Columbia’s oyster sector.

Over the past few months, they have been working to prevent a repeat scenario.

“The recall had a very serious impact on our industry – and it should be taken very seriously,” Mr. Pocock said in a recent interview. He owns and operates Sawmill Bay Shellfish and is also president of the BC Shellfish Grower’s Association.

“And I’m not just talking about the farmers; I’m talking about everyone right through to the server in the restaurant,” he added.

A workshop last November spawned a national working group focused on Vibrio with representatives from the Canadian Food Inspection Agency, Fisheries and Oceans Canada, Health Canada, the BC Centre for Disease Control (BCCDC) and provincial health authorities.

That group developed a prevention program for Vibrio, focusing on education, enhanced testing and improved communication between producers and government agencies.

On the education front, workshops for producers emphasized measures to control Vibrio, such as proper refrigeration during transport.

Oysters represent a relatively small chunk of British Columbia’s aquaculture sales – $13-million, compared with $380.4-million for salmon, according to a 2015 report by British Columbia’s Ministry of Agriculture – but are prized for their taste and local appeal.

“Shellfish are an important part of our business, and especially in the summertime, when patios are open, [oysters] go great with wine and it was disappointing we were unable to offer B.C. product for raw consumption,” said Guy Dean, vice-president of seafood distributor Albion Fisheries.

Yeah, especially since Vibrio produces a toxin that attacks the weak livers of persistent wine drinkers.

Raw is risky.

And this Guy ain’t your buddy. Or friend.

I don’t eat raw oysters: Gross and may have Vibrio

Following up a scientific report, Timothy B. Wheeler of the Bay Journal reports a 6-year-old outbreak of food poisoning linked to eating raw Chesapeake Bay oysters has left behind a lingering mystery. Scientists seeking to identify the water-borne pathogen that sickened a pair of Baltimore restaurant patrons have tracked the culprit to Asia.

Raw oystersHow a potent strain of Vibrio bacteria seemingly from so far away wound up in the Bay continues to puzzle Maryland health officials, who worked with researchers at the U.S. Food and Drug Administration to investigate the 2010 cases.

The microorganism could have gotten here in the ballast water of the many oceangoing ships that ply the Chesapeake every year, state and federal scientists suggested in a recently published journal article. Or, they added, perhaps it came via the introduction of non-native oysters or some exotic fish.

“It really is speculation,” acknowledged Dr. Clifford Mitchell, environmental health bureau director for the Maryland Department of Health and Mental Hygiene. “We didn’t sample ballast water. We didn’t take specimens that would lead us to know that we had fish coming over, or migration.”

But the case, published in the June issue of Applied and Environmental Microbiology, illustrates how disease-carrying organisms may travel around the world, researchers said. And while steps have been taken since 2010 to prevent the unintentional transport of pathogens, parasites and other potentially harmful organisms via ships’ ballast water, those safeguards still have significant gaps in them.

The bacterium involved in the 2010 food poisoning outbreak was Vibrio parahaemolyticus, strains of which are commonly found in coastal waters worldwide — including the Bay — though only some have been found to cause illness. When those are ingested, they can cause acute gastrointestinal distress, including diarrhea, stomach pain, nausea, fever and chills. It usually passes within a few days, but in rare cases can be more severe, especially in people with weakened immune systems.

There were 45 cases of Vibrio infections reported in Maryland in 2010, but it’s not that often, state health officials said, that they’re able to pinpoint the source of the bacteria that may have sickened a particular person. By the time laboratory tests identify Vibrio as the cause of someone’s GI distress and the information gets reported to the state, days or even weeks may have passed, and the food that person had eaten is long gone.

In this case, though, state health investigators got a lucky break. Two individuals who got sick said that shortly before they became ill that summer, they had eaten raw oysters at different Baltimore restaurants. They hadn’t traveled out of state or done anything else that likely could have exposed them.

When investigators visited the restaurants, they found the half-shells eaten by the two victims were from the Bay. And when they visited the Maryland aquaculture operation that supplied both eateries, investigators pulled some oysters from the water and discovered that they had Vibrio in them as well — 11 different potentially disease-causing strains, in fact. One of those appeared to match the Asian strain found in the two food poisoning victims.

Coos Bay Oyster Co.The investigation ended there, for the time being. Even though the Vibrio involved were similar, researchers couldn’t positively identify them as the same, using the analytic techniques they had at the time. “The chromosome patterns matched, but we weren’t sure how common that pattern was in the environment,” explained Robert Myers, director of the state health department’s laboratory administration. “We hadn’t seen it before.”

A few years later, though, “whole genome sequencing” technology became available, Myers said, giving researchers the ability to draw a more detailed map of an organism’s genetic makeup.

With that new, more powerful analytical tool, FDA researchers re-examined the Vibrio strains involved in the 2010 outbreak and those from the oysters that state health investigators had sampled. They identified them as belonging to a family of strains known as “sequence type 8.” 

When researchers consulted a worldwide Vibrio database, they found that the Maryland strains were unlike any seen to date in the United States. Instead, they were closely related to strains reported only in Asia, most recently in Hong Kong about four years before the outbreak.

Changes were made to shellfish safety protocols after a larger outbreak in 2013of Vibrio parahaemolyticus illnesses associated with eating raw oysters harvested along the Atlantic Coast. More than 100 people in 13 states, including Maryland and Virginia, became ill.  According to a spokesman for the Maryland Department of the Environment, which regulates shellfish harvest waters in the state, the Interstate Shellfish Sanitation Conference, a joint state-federal body, tightened its requirements for investigating such cases, closing implicated harvest areas and ordering a product recall when more than 10 cases are traced to a given area. 

But officials caution that the protocols are not foolproof, and cases like this are a reminder of the risk people run in consuming raw seafood, Mitchell said, especially if they have underlying health conditions.

The number of reported Vibrio infections in the state varies from year to year, but has been trending upward since 2005, according to state health data. Concentrations of the bacteria increase in warmer weather, and climate change could be a factor as Bay water temperatures tick upward. But Mitchell cautioned that the bacteria are present year-round.

“Given the number of people who eat oysters, certainly it’s a relatively small number of infections, but it can be a very significant one,” Mitchell said.

3 sick from Norovirus in raw oysters in Hong Kong

The Centre for Health Protection (CHP) of the Department of Health is today (January 12) investigating a food poisoning outbreak and reminds the public to maintain personal, food and environmental hygiene to prevent food-borne diseases.

Raw oystersThe outbreak has affected three women, all aged 27. They developed vomiting, abdominal pain, diarrhoea and fever about 24 to 40 hours after having dinner in a food premises in Quarry Bay in the evening of January 3. The trio then sought medical attention and no hospitalization was required.

They have remained in stable condition.

The stool specimen of one of them tested positive for norovirus upon laboratory testing by the hospital. The CHP’s initial enquiries revealed that the trio had consumed raw oysters.

Raw is risky: I only eat cooked oysters (and didn’t get any for our 7 fishes feast tonight)

Although Salmonella has been isolated from 7.4 to 8.6% of domestic raw oysters, representing a significant risk for food-borne illness, little is known about the factors that influence their initial colonization by Salmonella.

oysters.grillThis study tested the hypothesis that specific regulatory changes enable a portion of the invadingSalmonella population to colonize oysters.

An in vivo promoter probe library screen identified 19 unique regions as regulated during colonization. The mutants in the nearest corresponding downstream genes were tested for colonization defects in oysters. Only one mutation, in ssrB, resulted in a significantly reduced ability to colonize oysters compared to that of wild-type Salmonella. Because ssrBregulates Salmonella pathogenicity island 2 (SPI-2)-dependent infections in vertebrate macrophages, the possibility that ssrB mediated colonization of oyster hemocytes in a similar manner was examined. However, no difference in hemocyte colonization was observed.

The complementary hypothesis that signal exchange between Salmonella and the oyster’s native microbial community aids colonization was also tested. Signals that triggered responses in quorum sensing (QS) reporters were shown to be produced by oyster-associated bacteria and present in oyster tissue. However, no evidence for signal exchange was observed in vivo.

The sdiAreporter responded to salinity, suggesting that SdiA may also have a role in environmental sensing. Overall, this study suggests the initial colonization of live oysters by Salmonella is controlled by a limited number of regulators, includingssrB.

 Influence of Salmonella enterica Serovar Typhimurium ssrB on colonization of eastern oysters (Crassostrea virginica) as revealed by a promoter probe screen

Appl. Environ. Microbiol. January 2016 82:328-339; Accepted manuscript
posted online 23 October 2015, doi:10.1128/AEM.02870-15

Clayton E. Cox, Anita C. Wright, Michael McClelland, and Max Teplitski

http://aem.asm.org/content/82/1/328.abstract?etoc

6 sick from Vibrio in oysters in Mass.

State health and fishery officials are extending the closure of several oyster beds in Boston’s South Shore area because of illnesses linked to seasonal shellfish bacteria.

SUN0705N-Oyster7The beds in Duxbury Bay, Kingston Bay, Bluefish River, Back River and Plymouth Harbor have been under a 7-day precautionary closure since last week. Tuesday’s announcement extends that until Oct. 8. It could be extended again if more illnesses arise.

The Massachusetts Department of Health and the state Division of Marine Fisheries say six illnesses linked to contaminated oysters have been confirmed. The illnesses are blamed on the Vibrio bacteria that thrive in warmer ocean waters.

81 sick: Vibrio outbreak linked to raw oysters grows in Canada’s west

The Public Health Agency of Canada reports 5 additional cases of Vibrio parahaemolyticus that have been reported in British Columbia (4), and Saskatchewan (1).

Coos Bay Oyster Co.PHAC is collaborating with provincial public health partners, the Canadian Food Inspection Agency, the Department of Fisheries and Oceans and Health Canada to investigate 81 Canadian cases of Vibrio parahaemolyticus infections in British Columbia, Alberta, Saskatchewan and Ontario linked to raw shellfish. The majority of the illnesses have been linked to eating raw oysters.

The risk to Canadians is low, and illnesses can be avoided if shellfish are cooked before being eaten. People with weakened immune systems, young children, pregnant women and older adults are at increased risk for developing complications if they get sick.

Individuals became sick between May 26 and August 26, 2015 and all reported consumption of raw shellfish, primarily oysters.

Based on the investigation of the foodborne illness outbreak by the Canadian Food Inspection Agency, oysters harvested from British Columbia coastal waters for raw consumption on or before August 18, 2015 have been recalled from the marketplace. See the food recall warning for more information on the recalled products that were distributed nationally. Consumers should not consume the recalled products.

Growers upset, but ‘it’s not the handling’ Oyster farms in Mass. remain closed as more Vibrio illnesses reported

Katama Bay oyster farms will remain closed for another week following additional confirmed cases of Vibrio illness tied to the area, a state Department of Marine Fisheries official said Tuesday afternoon.

SUN0705N-Oyster7The 12 shellfishermen harvesting oysters out of Katama Bay were scheduled to resume operation on Thursday morning after a one-week precautionary closure announced last Wednesday by state health and fisheries officials. The closure was prompted because of three reported cases of Vibrio parahaemolyticus caused by consumption of raw oysters from Katama Bay.

Now the closure will be extended for another seven days due to three more confirmed cases of Vibrio from mid-August, state Vibrio program coordinator Chris Schillaci told the Edgartown shellfish committee at a meeting Tuesday. The meeting was attended by a small group of Katama Bay oyster farmers.

Under state guidelines, two to four illnesses within a 30-day period would result in a seven-day closure, while four or more illnesses require a 14-day closure. More than 10 illnesses would require a 21-day closure and a recall.

There have been six Vibrio cases reported from Katama Bay in the past 45 days, Edgartown shellfish constable Paul Bagnall said, and three in the last 30 days.

The Katama Bay closure is the first Vibrio-related shellfish closure in Massachusetts this year.

Katama and other oyster-producing areas around New England have seen more reported cases of Vibrio in recent years. This marks the third year in a row that Katama Bay oyster farms have been closed for some period of time in the late summer because of Vibrio.

Ryan Smith, a member of the shellfish committee and a Katama oyster farmer, said while demand remains high for farmed oysters, the repeated closures are stressful and there is a loss of business.

“It seems like nobody really knows what’s going on,” he said, adding that the closures seemed to start “out of nowhere” three years ago.

Oyster farmers peppered Mr. Schillaci with questions about how the illnesses were reported, accounted for and traced to the growing area, and discussed whether more stringent measures might be put in place in future years. In 2013 the state adopted strict protocols for handling oysters, and Mr. Schillaci said he’s observed Katama oyster farmers following those guidelines.

“It’s not the handling that’s the problem here and I truly believe that,” he said.

 

Mass. closes oyster beds on Martha’s Vineyard after three sickened

With west coast growers in B.C. fuming about a Canadian Food Inspection Agency recall of oysters, east coast Massachusetts has ordered closed an area of oyster beds in Martha’s Vineyard’s Katama Bay after three people became sick from consuming raw oysters from the area.

Raw oystersThe Katama Bay oyster beds will be closed for one week, DPH officials said.

The department confirmed three cases of vibrio — a bacteria that causes watery diarrhea, vomiting, fever and chills for up to three days when ingested — linked to oysters in the area.

 If additional cases of vibrio are confirmed, DPH said, the U.S. Food and Drug Administration could enforce an extended closure of the beds, located between Edgartown and Chappaquiddick Island.

 

Raw and risky: Hepatitis A cluster linked to oysters and clams in Taiwan

Our friends are off to China and Indonesia at the end of the week (start of summer holidays) so we’re having them over for dinner tomorrow, where I’ll offer up a seafood pasta (I simply cannot compete with Susan’s stir-fry and other Chinese dishes).

SUN0705N-Oyster7But with the holiday season approaching, there will – like no raw egg dishes — be no raw shellfish served in this house.

The Taiwan CDC reports 30 indigenous cases of Hepatitis A from Oct. to Nov. 2014, in which more than 80 percent of the patients required hospitalization for their illness.

According to the epidemiological investigation, most patients consumed raw bivalves such as oyster and clams during the disease incubation period.

This has prompted the Taiwan CDC to remind the public to pay attention to personal dietary hygiene and consume only thoroughly cooked bivalves.

Bivalves such as oysters and clams concentrate the pathogens that are present in harvest waters.