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Paralytic Shellfish Poisoning

Confirmed Case

  • Clinical illness [1] within 24 hours of eating at risk shellfish [2] or contaminated seafoods [3];
  • Detection of saxitoxin or related toxins in samples of shellfish or contaminated seafoods that were consumed by an individual meeting the clinical case definition, in edible tissues in excess of 0.8 mg/kg (0.8 ppm);
  • Detection of saxitoxin in urine or feces collected within 24 hours of exposure and illness;
  • Detection of high levels of dinoflagellates (Alexandrium spp.) associated with shellfish poisoning in water from which epidemiologically related shellfish [2] or seafood [3] were gathered.

Probable Case

  • Clinical illness [1] within 12 hours of consumption of at risk shellfish [2] or contaminated seafoods [3] and in the absence of other known causes.


  1. Clinical illness defined as: neurological symptoms such as paresthesia and/or paralysis involving the mouth and extremities, which may be accompanied by gastrointestinal symptoms. 
  2. At risk shellfish include filter feeding molluscan bivalve shellfish: clams, mussels, scallops (digestive tissues), oysters, cockles, and whelks.
  3. Seafood at risk of being contaminated are any species that feeds on plankton, including crabs, prawns, squid and planktiverous fish eaten whole (e.g., sardines, anchovies). Rarely, edible algae may be contaminated via contact with toxic phytoplankton. 
SOURCE: Paralytic Shellfish Poisoning ( )
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