Case Definition: Saxitoxin

Clinical description

Exposure to saxitoxin most commonly occurs following ingestion of certain fish that contain it in their tissues. Ingestion of saxitoxin can cause numbness of the oral mucosa as quickly as 30 minutes after exposure. In severe poisoning, illness typically progresses rapidly and may include gastrointestinal (nausea, vomiting) and neurological (cranial nerve dysfunction, a floating sensation, headache, muscle weakness, parasthesias and vertigo) signs and symptoms. Respiratory failure and death can occur from paralysis (1-5).

Laboratory criteria for diagnosis

  • Biologic: A case in which saxitoxin in urine is detected, as determined by the CDC laboratory. (1-5)

– OR-

  • Environmental: Detection of saxitoxin in ingested compounds or seafood. (7-10)

Case classification

  • Suspected: A case in which a potentially exposed person is being evaluated by health-care workers or public health officials for poisoning by a particular chemical agent, but no specific credible threat exists.
  • Probable: A clinically compatible case in which a high index of suspicion (credible threat or patient history regarding location and time) exists for saxitoxin exposure, or an epidemiologic link exists between this case and a laboratory-confirmed case.
  • Confirmed: A clinically compatible case in which laboratory tests have confirmed exposure.

The case can be confirmed if laboratory testing was not performed because either a predominant amount of clinical and nonspecific laboratory evidence of a particular chemical was present or the etiology of the agent is known with 100% certainty.

Additional resources

  1. Gessner BD, Middaugh JP, Doucette GJ. Paralytic shellfish poisoning in Kodiak, Alaska. West J Med 1997:67:351-3.
  2. Janiszewski L. The action of toxins on the voltage-gated sodium channel. Pol J Pharmacol Pharm 1990;42:581-8.
  3. Rodrigue DC, Etzel RA, Hall S, et al. Lethal paralytic shellfish poisoning in Guatemala. Am J Trop Med Hyg 1990;42:267-71.
  4. Shoff WH, Shepherd SM. Scombroid, ciguatera, and other seafood intoxications. In: Ford MD, Delaney KA, Ling LJ, Erickson T, eds. Clinical toxicology. Philadelphia, PA: W.B. Saunders; 2001:959-69.
  5. Tunik MG. Chapter 45: Food Poisoning. In: Nelson LS, Lewin NA, Howland MA, Hoffman RS, Goldfrank LR, Flomenbaum NE, eds. Goldfrank’s Toxicologic Emergencies. 9th ed. New York, NY: McGraw-Hill; 2011: 668-81.
  6. Etheridge SM. Paralytic shellfish poisoning: seafood safety and human health perspectives. Toxicon. 2010 Aug 15; 56(2): 108-22.
  7. NIOSH. NIOSH manual of analytical methods [online]. 2003. [cited 2013 Apr 5]. Available from URL:
  8. OSHA. Sampling and analytical methods [online]. 2010. [cited 2013 Apr 5]. Available from URL: icon.
  9. FDA. Food: Laboratory methods [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
  10. EPA. Selected analytical methods: chemical methods query [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
Page last reviewed: April 4, 2018