Paralytic Shellfish Poisoning ¡ª Oregon, May¨CJuly 2024

What did we do?

• During Memorial Day weekend in 2024, there were reports of 21 people with suspected paralytic shellfish poisoning (PSP). Researchers investigated to confirm outbreak source, assess magnitude, and implement control measures.

What did we find?

• 42 cases were identified through reports to Oregon Poison Center, online surveys, contact investigation, and passive surveillance.
• 39 cases were presumptive and three confirmed.
• Median age was 47 years (range: 11-76); 55% were male.
• 54% of individuals who fell sick sought medical care, 17% were hospitalized, and one person received mechanical ventilator treatment. Ill individuals who did not seek medical care were generally older, sick longer, and more likely to live in rural or coastal counties compared to those who did seek care.
• One person who fell sick consumed mussels and clams; remaining people who fell sick consumed only mussels (34), clams (6), or oysters (1).
• Two leftover mussel samples harvested May 25 demonstrated saxitoxin levels 44-68 times above closure limits.
• Mussel harvest location was reported by 30 people who fell sick and 34 people who did not. People who fell sick harvested north of latitude 45.12535°N; people who did not get sick harvested farther south.

Why does it matter?

• This outbreak was Oregon’s largest recorded PSP outbreak. Prior to this outbreak and since 2012, only 7 cases of PSP were reported in Oregon.

• Increased saxitoxin testing frequency and public education might help prevent illnesses.

• Illness reports to Oregon Poison Center and Oregon Health Authority informed beach closures by Oregon Department of Fish and Wildlife and Oregon Department of Agriculture.

• Building strong partnerships among state agencies is critical to preventing future outbreaks.

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Abstract Category: Paralytic Shellfish Poisoning