PORTLAND, Ore. — The U.S. Food and Drug Administration says consumers should avoid eating shellfish from Oregon and Washington state because they may be contaminated with a toxin that can cause paralytic shellfish poisoning.
At least 31 people have become sick so far, according to the Oregon Health Authority. Here’s what you need to know about the federal agency’s recommendations.
What is the FDA warning?
The warning says to avoid oysters and clams harvested in Netts Bay and Tillamook Bay in northern Oregon after May 28, and shellfish harvested around Willapa Bay in southern Washington after May 26.
These may be contaminated with high levels of paralytic shellfish poisoning (PSP), a naturally occurring toxin produced by algae.
Shellfish harvested from these regions during that time were distributed not only to Oregon and Washington, but also to Arizona, California, Colorado, Hawaii, Nevada, and New York.
The FDA has warned restaurants and retailers in those states not to serve the product.
What do we know so far?
High levels of the toxin were first detected in shellfish off the Oregon coast on May 17, according to Oregon Fish and Wildlife officials.
Since then, an outbreak of paralytic shellfish poisoning has sickened at least 31 people in Oregon, according to the Oregon Health Authority.
The department is asking people who have harvested or eaten shellfish from Oregon since May 13 to fill out a questionnaire that will help investigators determine the source of the infection and how many people are infected.
Oregon officials have banned the harvesting of mussels, clams and clams along the entire state coast.
USDA officials also closed three bays to commercial oyster harvesting, including those listed in the FDA advisory.
Authorities in neighboring Washington state have also banned the harvesting of shellfish, including mussels, clams, scallops and oysters, along the state’s Pacific coast, according to a shellfish safety map created by the Washington State Department of Health.
What is paralytic shellfish poisoning?
Paralytic shellfish poisoning (PSP) is caused by saxitoxin, a naturally occurring toxin produced by algae that is a neurotoxin and can damage nervous tissue.
According to the Oregon Health Authority, people who eat shellfish contaminated with high levels of saxitoxin usually start to feel ill within 30 to 60 minutes.
Symptoms include numbness in the mouth and lips, vomiting, diarrhea, shortness of breath, and in severe cases, irregular heartbeat.
There is no antidote for PSP, health officials say, and severe cases can require a ventilator to help people breathe.
Officials warn that cooking or freezing contaminated shellfish does not destroy the toxins or make it safe to eat.
What is the cause?
Matthew Hunter, shellfish program manager for the Oregon Department of Fish and Wildlife, said at a press conference that the “very large” algal bloom had produced “unprecedented levels” of PSP toxins along the Oregon coast.
The toxins accumulated in the shellfish and made some people ill when they ate them.
According to the National Oceanic and Atmospheric Administration, the factors that cause harmful algal blooms are not well understood, but certain factors resulting from both natural processes and human activities are thought to play a role.
“Research has shown that many algae species thrive when wind and water currents are favorable.” The agency says A webpage explaining harmful algal blooms.
The report said some algal blooms were caused by “stagnation of the hydrological cycle, abnormally high water temperatures, and extreme weather events such as hurricanes, floods and droughts.”
Algae blooms can also increase when nutrients used in fertilizers, mainly phosphorus and nitrogen, run off into water bodies, according to the agency.
How long will this continue?
Oregon officials said it could take weeks, months or even a year for toxin levels to drop in some types of shellfish.
According to Hunter, of the Oregon Department of Fish and Wildlife, mussels can quickly build up paralytic shellfish toxins, but they can also quickly excrete them.
Because of this, it may take anywhere from two weeks to a month for the mussels to eliminate the toxin.
But the razor clams are slow to do so: Due to the current high levels of toxins, it may take several months or even a year for them to cleanse themselves, Hunter said.
How common is this?
Hunter said such high levels of paralytic shellfish poisoning have not been detected in Oregon in decades, in part because of a 1992 shellfish harvesting ban.
But PSP has been prevalent in the region’s waters for centuries, he said.
What is the impact on the economy?
The fishing ban could deal a blow to fishing industries in the Pacific Northwest.
According to the National Oceanic and Atmospheric Administration, the shellfish industry contributes $270 million to the region’s economy each year and employs about 3,200 people.
