Martha’s Vineyard oysters could cause foodborne illness

Now that it’s September, it’s unofficially oyster season in New England. Having grown up amongst Greater Boston’s idyllic fishing communities, I’ve abided by the old adage only eat oysters during months that end in ‘ber.’ September is no exception; except for the fact that oyster beds off the coast of Edgartown on Martha’s Vineyard have been closed.

Coos Bay Oyster Co.On Wednesday afternoon, the Massachusetts Department of Public Health and the Massachusetts Department of Fish and Game, Division of Marine Fisheries announced the precautionary closure of the oyster beds in Katama Bay. The two departments determined that a certain environmental condition has become present which can often lead to an infestation of Vibrio parahaemolyticus – a bacteria that can cause gastrointestinal illness when ingested.

Vibrio outbreak prompts changes in oyster handling

I’ve only once had raw oysters, on a trip to New Zealand while in graduate school where some Kiwi food safety folks urged me to try the delicacy.

They were slimy.

I determined that the taste benefit wasn’t worth the risks for me.

According to the Vineland Gazette, a 2013 outbreak of Vibrio parahaemolyticus, linked to Katama Bay (MA) oysters prompted the Massachusetts Massachusetts Department of Fish and Game, Division of Marine Fisheries and the Department of Public Health, Bureau of Environmental Health, Food Protection Program to develop a plan to limit Vibrio risks.SUN0705N-Oyster7

A Vp control plan takes effect next month that will require faster cooling and delivery of oysters, changes in handling methods for harvesters, specific requirements for icing and new rules for record keeping among commercial oyster growers.

Backed by the state Division of Marine Fisheries, the rules will be in effect from May 19 through Oct. 19. The U.S. Food and Drug Administration recommended last year that Massachusetts develop a plan to control Vp during the warm weather months to prevent illness. 

FSA seeking for research on norovirus removal from oysters

Norovirus in oysters is a global issue and the UK Food Standards Agency, home of piping hot, is looking for some research help. As the virus bioaccumulates and is tough to cook out of shellfish, lots of folks are looking for virus removal strategies.Beautiful-Opened-Oyster

According to Fish Farmer, the Food Standards Agency (FSA) is inviting tenders to design and execute a research study to identify and evaluate possible enhancements to improve norovirus removal from live oysters during shellfish depuration processes.

The FSA wants to commission work to quantify and optimise the effectiveness of standard UK depuration practices in reducing norovirus in oysters and to explore the potential for novel approaches to significantly improve the effectiveness of this process.

The study should include reviews of relevant available evidence (published and unpublished) as the starting point for a fully justified laboratory-based project which will improve the controls that can be applied to current UK depuration practices, to reduce the levels of norovirus in oysters sold for public consumption.

Maybe Heston Blumenthal is on the review panel.  If so, research into food handlers working while ill might predictably be next on the docket.

2013 Colchester Oyster Feast source of outbreak

The Colchester Oyster Feast is kind of a big deal. Dating back to the 14th century and boasting a couple of to-be-kings as former guests (King Edward VIII and King George VI) it is the place to be in October. The event even has its own Wikipedia page.

And in 2013, it also was the source of an outbreak.1891cs

According to the Essex County Standard, 54 attendees became ill after eating Irish oysters at the annual festival.

A total of 200 guests attended the civic event at Colchester’s Moot Hall last October.
Within days, 13 guests reported they were unwell and an investigation was launched by Public Health England.

Questionnaires were sent out and 54 people reported they had been sick, including Colchester Council chief executive Adrian Pritchard.

3 sick with Campylobacter in Oregon, Coos Bay Oyster recalls shucked and in-shell oysters

Lynne Terry writes that Coos Bay Oyster Co. is recalling oysters over a food poisoning outbreak that has sickened at least three people in Oregon.

The company, based in Charleston, said it is pulling all of its shucked oysters and in-shell oysters sold to retail stores and wholesalers in Oregon and California.

The shucked oysters were sold in 1/2 gallon, quart, pint and half-pint containers with sell-by dates from Jan. 15 to Feb. 17. The containers carry the Coos Bay Oyster Co. label and Coos Bay Oyster Co.are marked raw/ready-to-eat shucked oysters.

The oysters in-shell were distributed in red onion sacks, each containing five dozen oysters of various sizes. They, too, have the company’s label, with harvest dates from December 2013 to January 2014.

59 sick; summer of shellfish outbreaks

In Seattle, King County health officials report there were 13 suspected cases of the saltwater bacteria Vibrio parahaemolyticus in the county during July, compared to an average of four reported in that month in recent years. Since the beginning of seven.fish.girls.2.dec.12August, an additional eight cases have been confirmed, while King County would typically only see six for the entire month.

Across Washington state, more than 40 residents have gotten sick with vibriosis.

“This is probably the tip of the iceberg,” said Dr. Jeff Duchin, chief of communicable disease for Seattle & King County Public Health. “For every case that is reported, an estimated 142 additional cases go unreported.”

People typically get vibriosis from eating raw or undercooked shellfish, particularly oysters. Residents who have pre-existing medical conditions or who take antacids regularly are at higher risk for illness from the vibrio infection.

Since June 2013, Connecticut has reported 19 confirmed cases of Vibrio parahaemolyticus infection, compared to an average of seven cases reported during the same time period in the past two years.

Shellfish should be cooked to an internal temperature of 145 degrees for at least 15 seconds, according to the U.S. Centers for Disease Control.

Not sure where that number came from, but I grill mine.

The Canadian Food Inspection Agency (CFIA) is warning the public not to serve or consume the raw shellfish products seven.fish.bbq.dec.11described below because they may contain paralytic shellfish toxins that can cause illness if consumed.

These shellfish products were primarily distributed to wholesalers and institutional clients such as restaurants. However, the affected shellfish products may also have been sold in smaller quantities at some retail seafood counters. Consumers who are unsure whether they have the affected products are advised to check with their retailer or supplier.

These products have been distributed in Alberta and British Columbia. However, they may have been distributed in other provinces and territories.

Norovirus, Vibrio risk in raw oysters is global

Those same Korean oysters the U.S. banned because of norovirus sickened at least 62 people who dined at three different outlets of a well-known chain buffet restaurant in China in June.

According to China NewsNow, the Department of Health will fine the importer NT60 000 to 6 mil and 150,000 oysters prohibited from sale have been ordered to be destroyed.

The U.S. Food and Drug Administration also reiterated earlier advice Friday not to eat raw or partially cooked oysters and clams (shellfish) with tags listing Oyster Bay Harbor, in Nassau County, N.Y., as the harvest area, following illnesses reported in several states caused by Vibrio parahaemolyticus bacteria.

Washington state says, please cook your oysters

I don’t know any food microbiologists who eat raw oysters; they may exist, but maybe I only know the drunks and they know better than to play with Vibrio and its liver-specific toxins.

And every time we post something about raw oysters, producers and government-types say we have no idea what we’re talking about – and provide no data.

So this isn’t me, it’s from the Washington state department of health via Seattlepi, which is telling Washingtonians to thoroughly cook their oysters.

The department says that cooking shellfish until the shells open is not enough for kill harmful bacteria.

Summer’s warmer temperatures mean that levels of the bacteria Vibrio parahaemolyticus increase in state waters. Eating an oyster with the Vibrio bacteria can lead to diarrhea, stomach cramps, nausea, vomiting, headache, fever, and chills. It says that symptoms usually appear within 12-24 hours after eating infected shellfish and usually last from two to seven days.

The department recommends oysters should be cooked to an internal temperature of 145 degrees for at least 15 seconds to thoroughly kill the bacteria.

Yes, I temp my oysters with a thermometer. Because I know a few drunks and don’t want to kill them.

Freezing oysters doesn’t do much for food safety, except make clusters of illnesses hard to connect

There are lots of food safety myths floating around like color is a good indicator of safe temperatures or the 3-second rule. One that popped up last week in a class I was guest lecturing in: freezing food kills things. I think this comes from some old parasite-reducing practices (fish especially) but someone asked specifically about shellfish – and whether freezing things like oysters, shrimp or clams does anything. Depends on the target pathogen, the risks with oysters specifically are viral (Noro or Hep A). So freezing might do something for the worms, but it’s not going to do much of anything to reduce viruses.

In this week’s Morbidity and Mortality Weekly Report (still my favorite publication title) investigators discuss a Washington State outbreak associated with frozen raw oysters.

Some highlights:

On October 19, 2011, Public Health – Seattle & King County was contacted regarding a woman who had experienced acute gastroenteritis after dining at a local restaurant with friends. Staff members interviewed the diners and confirmed that three of the seven in the party had consumed a raw oyster dish. Within 18–36 hours after consumption, the three had onsets of aches, nausea, and nonbloody diarrhea lasting 24–48 hours. One ill diner also reported vomiting. The four diners who had not eaten the raw oysters did not become ill.

An inspection of a walk-in freezer at the restaurant revealed eight 3-pound bags of frozen raw oysters, which the restaurant indicated had been an ingredient of the dish consumed by the ill diners. The oysters had been imported from South Korea by company A and shipped to a local vendor, which sold them to the restaurant. All eight bags were sent to the Food and Drug Administration’s Gulf Coast Seafood Laboratory for norovirus testing and characterization by real-time reverse transcription–polymerase chain reaction (rRT-PCR).

A stool specimen from one of two ill diners collected 17 days after symptom onset tested positive for norovirus; sequence analysis identified GI.1 and GII.17 strains. Sequence analysis of the oysters identified a GII.3 strain. Because oysters can harbor multiple norovirus strains that are unequally amplified by rRT-PCR, discordance between stool specimens and food samples in shellfish-associated norovirus outbreaks is common and does not rule out an association. On November 4, 2011, company A recalled its frozen raw oysters.

The frozen oysters implicated in this outbreak were distributed internationally and had a 2-year shelf-life.
Such contamination has potential for exposing persons widely dispersed in space and time, making cases difficult to identify or link through traditional complaint-based surveillance

Don’t add poop: how to prevent norovirus in oysters

 The most effective public health measures to protect consumers from exposure to norovirus in oysters are to produce oysters in areas which are not contaminated or to prevent contamination of mollusc production areas.

And current methods used to remove norovirus in shellfish are not an effective means of reducing contamination.

So says the European Food Safety Authority (EFSA) Panel on Biological Hazards (BIOHAZ Panel) in a new risk assessment.

The Panel recommends establishing acceptable limits for the presence of virus in oysters that are harvested and placed on the market in the European Union. In addition, an EU-wide baseline survey on norovirus in oysters should be carried out to provide information on overall consumer exposure as well as the public health impact of control measures.

Norovirus is transmitted through the consumption of food or water contaminated with fecal matter or through person-to-person contact or contact with infected surfaces. Oysters contaminated with norovirus pose a particular risk to human health as they are often consumed raw.

EFSA’s BIOHAZ Panel concludes that norovirus is highly infectious and that the amount of the virus detected in oysters linked to human cases can vary greatly.

Scientists highlight that norovirus is frequently detected in oysters in Europe which comply with existing EU control standards for bivalve molluscs.