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ON JUNE 6, 2011, THE SECTION OF EPIdemiology (SOE) of the Alaska Division of Public Health was notified of a case of paralytic shellfish poisoning
(PSP) in southeast Alaska. In collaboration with local partners, SOE investigated and identified a total of eight confirmed and 13 probable PSP cases that occurred during May—June 2011.
Warnings to avoid noncommercially harvested shellfish were broadcast on local radio and television and displayed at beaches and in post offices, government offices, and businesses throughout the region. Commercially harvested shellfish, which are tested for the presence of PSP-causing toxins, were safe. Because the risk for PSP is unpredictable, persons who consume noncommercially harvested Alaskan shellfish should know that they are at risk for PSP, and suspected cases should be reported promptly to SOE to initiate control measures in the affected area. On June 3, 2011, a man aged 52 years residing in Metlakatla, on Annette Island in southeast Alaska, awoke from a nap with numbness around his mouth, tingling in his hands, and slight dyspnea. He was taken to the Annette
Island Service Unit, the community’s health center, where a clinician inquired about recent seafood consumption. After the man reported eating a meal of steamed cockles shortly before his nap, the clinician diagnosed
PSP. The man was transported to Ketchikan where, having become weak and unable to sit up in bed without assistance, he was admitted to the intensivecare unit.
PSP primarily results from ingestion of saxitoxins, toxins produced
by marine dinoflagellate algae that accumulate in bivalve mollusks (e.g., butter clams, cockles, geoducks, and mussels). 1 PSP is a potentially fatal neuroparalytic condition. Signs and symptoms of PSP range from mild, short-lived paresthesias of the mouth or extremities to severe, lifethreatening paralysis.1 Because PSP is such a serious condition and because a case indicates widespread risk to the shellfish-consuming population of the affected area, immediate reporting of PSP cases to SOE by health-care providers is mandatory in
When SOE was notified of the probable case of PSP (in patient A) on June
6, they also were informed by a nurse in Metlakatla that other community members had eaten cockles and had experienced PSP symptoms. That afternoon, two SOE epidemiologists traveled to Metlakatla (population: 1,460 persons) to investigate. The epidemiologists met with a visiting public health nurse onsite and conducted active case finding by broadcasting messages on local television and radio and through word-of-mouth among community members. For this investigation, a probable case of PSP was defined as a compatible illness, including paresthesias, in a person shortly after consumption of noncommercially harvested shellfish from
Alaska waters during spring 2011. A confirmed case also met this case definition and had detectable saxitoxins in urine or levels Ն80 µg saxitoxins/100 g of meat (the level at which product is considered unsafe) in the shellfish that had been consumed before illness onset. SOE identified an additional 12 probable cases in Metlakatla and used a structured questionnaire for patient interviews. The team collected shellfish from two beaches where shellfish associated with PSP had been harvested. They also collected frozen cockles from a community member who harvested them with the index patient (patient A) before that patient became ill.
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Paralytic shellfish poisoning (PSP) is a potentially fatal yet preventable condition that results from ingestion of saxitoxins, a family of neurotoxins produced in certain marine algae and sometimes…