At least 20 people contracted a potentially deadly foodborne illness after eating mussels from the Oregon coast this past weekend, the Oregon Health Authority reported.

The people who fell ill were all diagnosed with paralytic shellfish poisoning (PSP) after “recreationally harvesting” mussels at Short Beach, Hug Point and the Seaside area, according to OHA. PSP — which has no antidote — is the most common and severe form of shellfish poisoning.

Symptoms usually appear between a half an hour and 60 minutes after eating contaminated shellfish and include numbness of the mouth and lips, tingling, nausea, vomiting, diarrhea, weakness and, in severe cases, shortness of breath or irregular heartbeat. The disease can be deadly for children, according to OHA.

None of the people who fell ill this weekend died, but some were hospitalized, OHA reported. Emilio DeBess, an Oregon Public Health Division epidemiologist, advised anyone who gathered shellfish from the contaminated area to throw them out immediately, pointing out that the naturally occurring marine toxins are not destroyed through cooking or freezing.

The recommendations do not apply to mussels harvested commercially, purchased at a grocery store or eaten at a restaurant.

Officials had already implemented a mussel-harvesting closure along the southern Oregon coast, but they extended it on Sunday to include the three locations that reportedly sparked the PSP outbreak. The closed area now stretches from Seal Rock State Park north to the Washington border.

OHA urges anyone who ate recreationally harvested mussels from the contaminated area and feels ill to see a doctor immediately.

– Sujena Soumyanath is a reporter on The Oregonian/OregonLive’s public-safety team. You can reach her at 503-221-4309 or ssoumyanath@oregonian.com