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Cause:
Ingestion of shellfish with a toxin from the phytoplankton Alexandrium catenella
for paralytic shellfish poisoning (PSP), ingestion of shellfish with a toxin from marine
diatoms Pseudo-nitzschia for domoic acid shellfish poisoning (DASP).
Illness and treatment:
PSP symptoms begin minutes or hours after eating contaminated shellfish and may include
numbness of the mouths and limbs. Severe PSP progresses rapidly to paralysis and
respiratory arrest, and may require mechanical ventilation. For DASP gastrointestinal
symptoms begin within 24 hours of ingestion and may be followed within 48 hours by
neurological symptoms including confusion, short-term memory loss, seizures, respiratory secretions,
and coma. There is no anti-toxin for either.
Sources:
Bivalve mollusks such as clams, oysters, mussels, and geoduck concentrate PSP toxin. Razor clams,
other bivalve mollusks, and Dungeness crab concentrate DASP toxin. There is no person-to-person spread.
Additional risks:
PSP is only rarely associated with reddish discoloration of the water, although the term
“red tide” is popularly used. Either toxin can be present in dangerous amounts even when
the harvest site water looks clean. Freezing or cooking does not destroy the toxins.
Prevention:
Before harvesting shellfish check the Marine Biotoxin Hotline (1-800-562-5632) or
web site
for updates on affected sites and site closures, which may not always have signs posted.
Recent Washington trends:
Two clusters of PSP have been reported during the past 10 years (7 reports in 2000 and 5
in 1998). Both clusters were associated with mussels gathered recreationally from south
Puget Sound waters.
2010:
No cases were reported.
Purpose of Reporting and Surveillance
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To identify whether the source of transmission is a major pubic health concern
(e.g., a commercial shellfish product or recreational harvest area) and to prevent
further transmission from such sources.
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To identify others who shared the exposure and educate them regarding symptoms of paralytic
shellfish poisoning to facilitate rapid diagnosis.
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When the source is a risk to only a few individuals (e.g., shellfish harvested
from an area closed to harvesting), to inform those individuals how they can
reduce their risk of future exposure.
Legal Reporting Requirements
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Health care providers:
immediately notifiable to local health jurisdiction.
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Health care facilities:
immediately notifiable to local health jurisdiction.
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Laboratories:
no requirements for reporting.
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Local health jurisdictions:
immediately notifiable to the Washington State Department of Health (DOH)
Communicable Disease Epidemiology (CDE) (1-877-539-4344 or 206-418-5500).
Last update
December 2011 |
