Neurotoxic Shellfish

Epidemiology

Geography (Clin Infect Dis, 2005) [MEDLINE] and (Epidemiol Infect, 2010) [MEDLINE]

  • Southeastern Coast of the US
  • Gulf of Mexico
  • Caribbean
  • New Zealand

Outbreaks

  • Two Outbreaks were Reported to the CDC In the US Between 1998-2002 (Clin Infect Dis, 2005) [MEDLINE]
    • No Fatalities were Reported

Etiology

  • Ingestion of Brevetoxin-Contaminated Bivalve Shellfish
    • Cases are Associated with Occurrence of “Red Tides”
  • Inhalation of Sea Spray/Aerosols
    • Cases are Associated with Occurrence of “Red Tides”

Physiology

  • Brevetoxins
    • Brevetoxins are Synthesized by Dinoflagellate, Karenia Brevis (Formerly Gymnodidium Breve and Ptychodiscus Brevis): these dinoflagellates synthesize both hemolytic toxins and neurotoxins (Epidemiol Infect, 2010) [MEDLINE]
    • Brevetoxins are Taken Up by Bivalve Shellfish and are Aerosolized During Algal Blooms
    • Brevetoxins Act to Impair Sodium Channel Function and Inhibit Cathepsins (Which are Lysosomal Proteinases Found in Macrophages and Other Phagocytes)

Diagnosis

  • Detection of Brevetoxins in Suspected Contaminated Shellfish

Clinical Manifestations

Ingestion Syndrome

General Comments

  • Onset: onset within 30 min-3 hrs after ingestion

Gastrointestinal Manifestations

Neurologic Manifestations

Rheumatologic Manifestations

Inhalation Syndrome (Aerosolized Red Tide Respiratory Irritation, ARTRI)

Otolaryngologic Manifestations

Pulmonary Manifestations


Treatment

Ingestion Syndrome

General Comments

  • Clinical Manifestations Usually Resolve within a 72 hrs

Supportive Care

Activated Charcoal (see Activated Charcoal, Activated Charcoal)

  • Recommended to Bind Toxin in Unabsorbed Food (Although Evidence is Lacking)

Inhalation Syndrome


Prognosis

  • Not Usually Fatal in Humans
    • However, Fatalities are Common in Birds, Fish, and Manatees

References

  • Clinical and epidemiological features of neurotoxic shellfish poisoning in North Carolina. Am J Public Health. 1991 Apr;81(4):471-4 [MEDLINE]
  • Shellfish poisonings. Shoreland’s Travel Medicine Monthly. 1999;3:1 [MEDLINE]
  • Pfiesteria, “the cell from hell,” and other toxic algal nightmares. Clin Infect Dis. 1999;28(6):1191 [MEDLINE]
  • Neurotoxic shellfish poisoning and brevetoxin metabolites: a case study from Florida. Toxicon. 2000;38(7):981 [MEDLINE]
  • Illnesses caused by marine toxins. Clin Infect Dis. 2005;41(9):1290 [MEDLINE]
  • Aerosolized red-tide toxins (brevetoxins) and asthma. Chest. 2007;131(1):187 [MEDLINE]
  • Reported respiratory symptom intensity in asthmatics during exposure to aerosolized Florida red tide toxins. J Asthma. 2007;44(7):583 [MEDLINE]
  • Neurotoxins from marine dinoflagellates: a brief review. Mar Drugs. 2008 Jun 11;6(2):349-71. doi: 10.3390/md20080016 [MEDLINE]
  • Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40 [MEDLINE]