After the Heat Dome, Is It Safe to Eat Oregon Oysters?

Earlier this year, temperatures throughout much of the Pacific Northwest rose to dangerous highs, a surge that killed hundreds, including an Oregon farmworker. In the coastal waters off of Washington and British Columbia, mussels died by the hundreds, shells open, still attached to the rocks. And in the typically cool waters, home to some of the Pacific Northwest’s most coveted oysters, water temperatures climbed just high enough to allow vibrio bacteria to grow and multiply. As oysters sucked in the warm waters around them, the vibrio found a new home inside the mollusks’ shells, eventually sliding down the throats of hundreds of people throughout the Pacific Northwest — and causing a massive outbreak of vibriosis.

Vibriosis is deeply unpleasant. It can cause stomach cramping, diarrhea, and vomiting; the Centers for Disease Control and Prevention estimate that around 80,000 people get sick with vibriosis each year. People with compromised immune systems can die from their infections, and in fact, around 100 people do each year. The Washington State Department of Health released a statement last month tying an uptick in vibriosis cases to the heat dome in late June; the number of lab-reported cases in July blew past the average number of reported cases for that month to become the highest ever recorded for July.

Oregonians are some of the biggest consumers of Washington Kumamotos, Olympias, and Pacific oysters, which resulted in a number of Portland diners developing vibriosis symptoms over the summer. One such group included customers at Flying Fish Company, the celebrated seafood market and restaurant owned by fishmonger and chef Lyf Gildersleeve. Gildersleeve prides himself on his responsible, high-quality shellfish and seafood sourcing, so when a few customers called him to report their vibriosis diagnoses, he was mortified. “They are supposed to be testing those waters weekly and then shutting down the beds when there are higher vibrio counts. Our customers got sick, they let us know, and then they shut down the beds,” Gildersleeve says. “Regardless if the beds are open or not, I don’t want my customers getting sick. Those people who got sick, it’s awful, I don’t want anyone to throw up because of my food.”

However, Teresa McCallion, a public information officer for the Washington State Department of Health, tells Eater Portland via email that vibrio testing is for “surveillance only” and that the department does “not use the data to close growing areas because the National Shellfish Sanitation Program (NSSP) Model Ordinance (our guide) does not provides [sic] a closure level of Vibrio counts.”

“We have to wait until the illnesses are reported by the ill person, processed, and investigated by the local health jurisdiction, then confirmed by our public health lab, and investigated by DOH,” she says. “This process takes time, unfortunately, which can delay closure. We closed Samish Bay on July 15, while most illnesses occurred from harvests between June 28 and July 4.”

As a result of the outbreak, Gildersleeve — and other seafood restaurants in Portland — have stopped serving Washington oysters, instead sourcing from places like Alaska and Maine. What the current uptick of vibriosis doesn’t account for, however, is how the heat waves impacted Oregon-harvested oysters, beds found in places like Netarts and Coos Bay. Turns out, the vibrio counts in Oregon oysters are much lower than the ones in certain Washington oysters, despite the heat wave.

“We have seen, and will likely continue to see, an increase in the number of vibrio cases this year,” says Dr. Emilio DeBess, a state epidemiologist who studies foodborne illnesses related to animals. “We pulled the tags, we communicated with the states where the oysters came from, and many of them are coming from Washington state.”

So far, the Oregon Department of Agriculture has not shut down any oyster harvesting areas along the Oregon Coast, and the Department of Human Services and Oregon Health Authority recorded only seven cases of vibrio in Oregon between January 1 and June 30 of 2021. Currently, there is no available data linking vibrio cases to Oregon waters.

In certain ways, the areas where Oregonians harvest oysters are particularly well-suited to avoiding vibrio. Places like Netarts Bay are shallower than Washington oyster habitats like Puget Sound; the water is regularly flushed out by the tides, which means vibrio doesn’t have the time to really multiply. “Vibrio is a natural inhabitant of the water… [Dangerous levels of vibrio] depend on the temperature, the dilution component, high tides versus low tides,” DeBess says. “If water moves in and out, there’s a dilution component, it takes those contaminants in and out as quickly as they can.”

As a result, some Portland restaurants have actually switched to selling more Oregon oysters, as opposed to the more widely available Washington oysters. After the vibrio debacle in Washington, Normandie chef Heather Kintler began sourcing oysters from Netarts as opposed to her typical Washington oysters. According to Nevor Shellfish Farm owner Travis Oja, the lack of Oregon oysters on Portland menus has less to do with the heat waves and more to do with the industry as a whole. “The boring truth here is that those Oregon shellfish are scarce because Oregon shellfish producers are scarce. Many of the ‘real’ Oregon farms are production farms — Pacific Seafood, Oregon Oyster Company, Clausen Oysters — growing larger oysters for shucked meats,” Oja says. “Maybe that explains the recent lack of Oregon-related vibrio infections — there aren’t a whole lot of Oregon oysters being consumed raw because there aren’t many.”

DeBess still thinks Oregonians should avoid eating raw oysters altogether, at any time of year — cooking oysters can kill vibrio, even if it’s present in high numbers — but when it comes to the current cases attributed to Oregon oysters, the numbers are slim. Knocking back an Oregon oyster on the half-shell probably won’t kill you, though eating raw oysters, in general, always carries some risk. And as temperatures continue to climb, it’s likely that vibrio will become even more prevalent, year after year — the same way wildfires impact vineyards, heat waves impact food cart owners, and a warming planet will impact all of us, in time.

• Oregon farmworker dies during heat wave [KGW]
• Like in ‘Postapocalyptic Movies’: Heat Wave Killed Marine Wildlife en Masse [The New York Times]
• Rise in Shellfish-Related Food Poisoning Is Likely Linked to Extreme Heat in the Pacific Northwest [Eater Seattle]