Clinic: Shellfish poisoning

Examine for venom effects

Local (gastrointestinal) Effects

• Nauese, vomiting, diarrhoea → Dehydration (!), abdomial pain.

Neurological effects (Peripheral nervous system)

• Acroparaesthesias, myalgia, muscle weakness, paralysis, including paralysis of the respiratory musculature → respiratory failure

Neurological EFFECTs (Central nervous system, including psychiatric symptoms)

• Coma, cerebral seizures (in the acute phase and spontaneous recurrent seizures weeks to months after ingestion), mutism, involuntary chewing and grimacing, emotional instability (uncontrolled screaming and aggression), headache, short-term memory loss, increased bronchial secretion

Cardiac effects

• Bradycardia, arrhythmia, hypotension. 

Laboratory and physical investigations

Detection of toxins
See Bian et al (2024)
Detection in trace amounts in human biological fluids (plasma, serum, urine) remains a problem. Concentrations in human fluids are much lower than in contaminated seafood.
See, e.g., Chen et al. (2025).

PSP

CK 
Increased (McCollum et al. 1968, Cheng et al. 1991) 
Electrophysiological investigations
Electrophysiological findings, which can be explained by incomplete blockade of sodium channels, distinguish PSP from most other acute-onset paralytic illnesses. Complete return to normal within 5 days (Long et al. 1990). Only cases of poisoning due to tetrodotoxin, a sodium channel blocker similar to saxitoxin, present an identical picture (Oda et al. 1989). 

Species-specific envenoming pattern

Important features and differential diagnosis between types of shellfish poisoning

PSP

• Acroparaesthesias without impairment of sensitivity to cold,
• Marked paralysis of the skeletal musculature in the majority of cases,
• In severe cases of poisoning the respiratory musculature is also affected,
• Respiratory failure is the cause of death in fatal cases,
• Gastroinstestinal signs and symptoms are not very pronounced. 

NSP

• NSP has a milder course than paralytic shellfish poisoning. 
• Likewise in comparison to ciguatera poisoning, which shows similarities with regard to symptoms. 
• The patient history with regard to the type of seafood consumed and the self-limiting and short-lived course of the illness are important distinguishing features.
• Gastrointestinal signs and symptoms.

ASP

• The acute phase of illness is characterised by a neuronal "hyperexcitation" syndrome that is most probably due to stimulation of central and possibly also peripheral neurons. 
• In the chronic phase of illness there is degeneration of neuronal structures in the hippocampus and the anterior horn cells of the spinal cord (Teitelbaum et al. 1990a).
• Severe persistent central nervous disorders distinguish ASP from other forms of shellfish poisoning with neurological disturbances.
• Gastrointestinal signs and symptoms

DSP

• Gastrointestinal signs and symptoms dominate.
• In contrast to the other forms of shellfish poisoning, no neurological signs or symptoms occur. 

PSP

Local (gastrointestinal) effects

• Nausea, vomiting, diarrhoea, abdominal pain (see Table in the Section ‘Studies’, below). 

Neurological effects

• Paraesthesias/hypaesthesias (perioral), paraesthesias/hypaesthesias (extremities), double images, dysarthria, paralysis of the skeletal musculature, including the respiratory musculature with respiratory insufficiency and respiratory failure, vertigo, ataxia, headache, temporary blindness, myalgias (muscle spasms?) (see table in the Section ‘Studies’, below).
• Time between ingestion and onset of symptoms: 2 h (median, range 30 min–8 h) (Rodrigue et al. 1990). “Symptom onset up to 3.5 hours after exposure and significant symptom progression within 6 hours with no symptomatic progression beyond 13 hours.” (Horowitz et al. 2026).

Time between ingestion and onset of symptoms

2 h (median, range 30 min–8 h) (Rodrigue et al. 1990). “Symptom onset up to 3.5 hours after exposure and significant symptom progression within 6 hours with no symptomatic progression beyond 13 hours.” (Horowitz et al. 2026).

NSP

Local (gastrointestinal) effects

• Nausea: 3 (0.5–18), 18 (1–48); vomiting: 3 (1–15), 8 (0.5–48); diarrhoea: 10 (1–18), 17 (2–48); abdominal pain: 5 (1–18), 17 (1–48) (Morris et al. 1991) (see also Watkins et al. 2008 and Table in the Section ‘Studies’, below) 
  Where relevant, the figures shown after the symptoms are the median time (in hours; range in parentheses) between ingestion and appearance of the symptom and the median duration of the symptom (in hours; range in parentheses).

Neurological effects 

• Paraesthesia: 4 (0.25–15), 8 (0.5–51); burning/painful sensation of the skin upon contact with cold objects: 7 (0.25–16), 8 (1–26); paresis/muscle weakness: 3 (0.25–17), 24 (0.5–51); vertigo: 3 (0.25–17), 16 (0.5–72); ataxia: 3 (0.25–14), 7 (0.5–40); myalgias: 6 (0.5–13), 7 (2–24); headache: 2 (0.5–12), 7 (2–24); chills: 2 (2–8), 11 (2–48) (Morris et al. 1991)(see also Watkins et al. 2008 and Table in the Section ‘Studies’, below)
  Where relevant, the figures shown after the symptoms are the median time (in hours; range in parentheses) between ingestion and appearance of the symptom and the median duration of the symptom (in hours; range in parentheses).

Other effects

• Rhinorrhoea, cough, conjunctivitis in non-asthmatics. Induces asthma attacks in asthmatics (Pierce 1986).

Time between ingestion and onset of symptoms (all symptoms)

 15 min–38 h (median 5.5 h) (Perl et al. 1990). 

ASP

Local (gastrointestinal) effects

• Nausea, vomiting, diarrhoea, abdominal cramps (see table in the Section ‘Studies’, below).

Neurological effects 

• Coma, cerebral seizures(in the acute phase and spontaneous recurrent seizures weeks to months after ingestion), mutism, involuntary chewing and grimacing, emotional instability (uncontrolled screaming and aggression), headache, short-term memory loss (positively associated with male gender, advanced age and dose of domoic acid), increased bronchial secretion (Perl et al. 1990a; Ramsdell and Gulland 2014; Teitelbaum et al. 1990a; see also Table in the Section ‘Studies’, below).

Cardial effects (see clinical epidemiology and references of reviews below)

• Unstable blood pressure, cardiac arrhythmias (see table in the Section ‘Studies’, below).

• Time between ingestion and onset of symptoms (all symptoms): 15 min–38 h (median 5.5 h) (Perl et al. 1990a).

Time between ingestion and onset of symptoms (all symptoms)

15 min–38 h (median 5.5 h) (Perl et al. 1990a).

DSP

Local (gastrointestinal) effects

• Nausea, vomiting, diarrhoea, abdominal pain (see Table in the Section ‘Studies’, below). 

Time between ingestion and onset of symptoms

30 min – several hours (rarely >12 h) (Yasumoto et al. 1978).

Morbidity

PSP
If a patient survives the first 12–18 h, the prognosis is good (Eastaugh and Shepherd 1989). Muscle weakness can persist for days to weeks.

NSP
The illness is self-limiting and resolves within several days with no lasting effects.

ASP
18% of patients were hospitalised for 4–101 days (median 37.5 days). The reason for hospitalisation was almost exclusively neurological disorders (Perl et al. 1990a).
Persistence of neurological disorders: chronic residual memory deficit, motor neuronopathy and axonopathy (Teitelbaum et al. 1990a).

DSP
Self-limiting illness that resolves within several days with no lasting effects.

Case fatality rate

PSP
Mortality may be considerable in individual outbreaks and is primarily dependent on the availability and success of symptomatic treatments. The cause of death is almost exclusively respiratory failure, which generally occurs 1–12 h after ingestion of the poison (Eastaugh and Shepherd 1989).
In an epidemic in Guatemala, the mortality rate was 26/187, whereby children <6 years had a mortality rate of 50% and adults >18 years of 7% (Rodrigue et al. 1990).
Between 1927 and 1985, 505 PSP cases were recorded in California, of which 32 ended fatally (MMWR 1983). In contrast, in 10 PSP epidemics in the USA between 1971 and 1977, there were no recorded fatalities (Hughes 1979).
2/116 died in an epidemic in Taiwan (Cheng et al. 1991).

NSP
No known fatalities to date.

ASP
3/107 (Perl et al. 1990a).

DSP
No known fatalities to date. 

Species-specific publications 
see ‘References’ at the end of the file.

Clinical management

See also Clinical Management: poisonous animals

for advice on diagnosis (clinical, laboratory) and treatment (supportive)

first aid

PSP
Gastric lavage, instillation of activated charcoal and laxatives are recommended; however, their value has not yet been documented in a controlled clinical trial.

NSP
No proven methods known.

ASP
No proven methods known.

DSP
No proven methods known.

Systemic supportive treatment

A general understanding of emergency medicine is required, or can be found in emergency medicine guidelines, e.g. ABCDE approach, WHO-ICRC Basic Emergency Care.

• Comprehensive ABCDE approach

• ICRC Basic Emergency Care: approach to the acutely ill and injured (SAMPLE  and ABCDE approach: first module)

Obey shellfish poisoning - specific features

see 'Species-specific envenoming pattern' above.

Key issues

Supportive treatment can be lifesaving

• Endotracheal intubation and artificial respiration
• Fluid and electrolyte and acid–base balance

PSP

• Endotracheal intubation and artificial respiration (may be necessary for a period of several days).

NSP

• Rehydration,

• Treatment of asthma attacks.

ASP

• Rehydration.
• Endotracheal intubation due to bronchial hypersecretion (Perl et al. 1990a), possibly artificial respiration.
• Unstable blood pressure: vasopressors, antihypertensives (Perl et al. 1990a).
• Cardiac dysrhythmias: antiarrhythmics (Perl et al. 1990a).

DSP

• Rehydration.

Specific treatment (antidote)

No specific antidotes available.

References

Reviews

• Anagnostou A, Abrams E. Is it food poisoning or allergy?: A diagnostic challenge revisited.Ann Allergy Asthma Immunol. 2023 Apr;130(4):403-404. PMID: 37005046. https://doi.org/10.1016/j.anai.2022.12.019
• Bian Y, Zhang Y, Feng XS, Gao HY.Marine toxins in seafood: Recent updates on sample pretreatment and determination techniques. Food Chem. 2024 Apr 16;438:137995. Epub 2023 Nov 20. PMID: 38029684. https://doi.org/10.1016/j.foodchem.2023.137995
• Chen J, Ling L, Liang S, Qu L, Li J, Zhang Y, Huang W, Huang L. Simultaneous determination of 12 lipophilic shellfish toxins in human plasma, serum, and urine using UPLC-MS/MS combined with PRiME HLB μElution platform. J Chromatogr A. 2025 Sep 27;1762:466418.  Epub ahead of print. PMID: 41038079. https://doi.org/10.1016/j.chroma.2025.466418
• Grattan LM, Holobaugh S, Morris JG Jr. Harmful Algal Blooms and Public Health. Harmful Algae. 2016 Jul;57(B):2-8. MID: 27616971; PMCID: PMC5016795. https://doi.org/10.1016/j.hal.2016.05.003
• Isbister GK, Kiernan MC. Neurotoxic marine poisoning. Lancet Neurol. 2005 Apr;4(4):219-28. PMID: 15778101. https://doi.org/10.1016/s1474-4422(05)70041-7
• James KJ, Carey B, O'Halloran J, van Pelt FN, Skrabáková Z. Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40. Epub 2010 Apr 23. PMID: 20412612. https://doi.org/10.1017/s0950268810000853
• Patel P, Komorowski AS, Mack DP. An allergist's approach to food poisoning. Ann Allergy Asthma Immunol. 2023 Apr;130(4):444-451. Epub 2022 Nov 2. PMID: 36334721. https://doi.org/10.1016/j.anai.2022.10.021
• Young N, Sharpe RA, Barciela R, Nichols G, Davidson K, Berdalet E, Fleming LE. Marine harmful algal blooms and human health: A systematic scoping review. Harmful Algae. 2020 Sep; 98:101901. Epub 2020 Sep 17. PMID: 33129458. https://doi.org/10.1016/j.hal.2020.101901

Original publications

PSP

• Cheng HS, Chua SO, Hung JS, Yip KK. Creatine kinase MB elevation in paralytic shellfish poisoning. Chest. 1991 Apr;99(4):1032-3. PMID: 2009759. https://doi.org/10.1378/chest.99.4.1032
• Eastaugh J, Shepherd S. Infectious and toxic syndromes from fish and shellfish consumption. A review. Arch Intern Med. 1989 Aug;149(8):1735-40. PMID: 2669661. doi:10.1001/archinte.1989.00390080021006
• Etheridge SM. Paralytic shellfish poisoning: seafood safety and human health perspectives. Toxicon. 2010 Aug 15;56(2):108-22Epub 2009 Dec 24. PMID: 20035780. https://doi.org/10.1016/j.toxicon.2009.12.013
• Horowitz KM, Cowdery CP, Hendrickson RG. Clinical Features of Paralytic Shellfish Poisoning: a Case Series from the 2024 Oregon Outbreak. J Med Toxicol. 2026 Jan;22(1):39-43. Epub 2025 Nov 28. PMID: 41315144; PMCID: PMC12835469. https://doi.org/10.1007/s13181-025-01112-6
• Hughes, J. (1979) Epidemiology of shellfish poisoning in the United States, 1971-1977. In Taylor, D. L., H. H. Seliger: Toxic dinoflagellate blooms. Elsevier, New York: 23-28
• Long RR, Sargent JC, Hammer K. Paralytic shellfish poisoning: a case report and serial ectrophysiologic observations. Neurology. 1990 Aug;40(8):1310-2. PMID: 2381544. https://doi.org/10.1212/wnl.40.8.1310
• McCollum JP, Pearson RC, Ingham HR, Wood PC, Dewar HA. An epidemic of mussel poisoning in North-East England. Lancet. 1968 Oct 5;2(7571):767-70. PMID: 4175564. https://doi.org/10.1016/s0140-6736(68)90967-7
• MMWR 1983.Annual mussel quarantine--California, 1983. MMWR Morb Mortal Wkly Rep. 1983 Jun 3;32(21):281. PMID: 6405172.
• Oda K, Araki K, Totoki T, Shibasaki H. Nerve conduction study of human tetrodotoxication. Neurology. 1989 May;39(5):743-5. PMID: 2710368. https://doi.org/10.1212/wnl.39.5.743
• Rodrigue DC, Etzel RA, Hall S, de Porras E, Velasquez OH, Tauxe RV, Kilbourne EM, Blake PA. Lethal paralytic shellfish poisoning in Guatemala. Am J Trop Med Hyg. 1990 Mar;42(3):267-71. PMID: 2316796. https://doi.org/10.4269/ajtmh.1990.42.267

NSP

• Morris PD, Campbell DS, Taylor TJ, Freeman JI. Clinical and epidemiological features of neurotoxic shellfish poisoning in North Carolina. Am J Public Health. 1991 Apr;81(4):471-4. PMID: 2003627; PMCID: PMC1405066. https://doi.org/10.2105/ajph.81.4.471
• Pierce RH. Red tide (Ptychodiscus brevis) toxin aerosols: a review. Toxicon. 1986;24(10):955-65. PMID: 3824403. https://doi.org/10.1016/0041-0101(86)90001-2
• Watkins SM, Reich A, Fleming LE, Hammond R. Neurotoxic shellfish poisoning. Mar Drugs. 2008;6(3):431-55. Epub 2008 Jul 12. PMID: 19005578; PMCID: PMC2579735. https://doi.org/10.3390/md20080021

ASP

• Perl TM, Bédard L, Kosatsky T, Hockin JC, Todd EC, Remis RS. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N Engl J Med. 1990a Jun 21;322(25):1775-80. PMID: 1971709.
• Perl TM, Bédard L, Kosatsky T, Hockin JC, Todd EC, McNutt LA, Remis RS. Amnesic shellfish poisoning: a new clinical syndrome due to domoic acid. Can Dis Wkly Rep. 1990b Sep;16 Suppl 1E:7-8.PMID: 2101742.
• Ramsdell JS, Gulland FM. Domoic acid epileptic disease. Mar Drugs. 2014 Mar 6;12(3):1185-207. PMID: 24663110; PMCID: PMC3967204. https://doi.org/10.3390/md12031185
• Teitelbaum JS, Zatorre RJ, Carpenter S, Gendron D, Evans AC, Gjedde A, Cashman NR. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N Engl J Med. 1990a Jun 21;322(25):1781-7. PMID: 1971710. https://doi.org/10.1056/nejm199006213222505
• Teitelbaum J. Acute manifestations of domoic acid poisoning: case presentations. Can Dis Wkly Rep. 1990b Sep;16 Suppl 1E:5-6.PMID: 2101741.
• Todd ECD. Domoic Acid and Amnesic Shellfish Poisoning - A Review. J Food Prot. 1993 Jan;56(1):69-83. PMID: 31084045. https://doi.org/10.4315/0362-028x-56.1.69  

DSP

• Yasumoto, T., Y. Oshima, M. Yamahuchi (1978) Occurence of a new type of shellfish poisoning in the Tohoku District. Bull. jap. Soc. sci. Fisheries 44: 1249-1255
  Retrospective study (first documented DSP epidemic). N = 164. Toxicity investigations in a mouse assay. Toxin that causes DSP not yet isolated.

 Sytemic supportive treatment

• WHO ABCDE Approach. https://cdn.who.int/media/docs/default-source/integrated-health-services-(ihs)/csy/bec-quick-cards/becp-edu29-pdf-en-finl.pdf?sfvrsn=2532d61b_2
• WHO-ICRC Basic Emergency Care: approach to the acutely ill and injured. https://www.who.int/publications-detail-redirect/basic-emergency-care-approach-to-the-acutely-ill-and-injured. https://cdn.who.int/media/docs/default-source/integrated-health-services-(ihs)/csy/bec-quick-cards/becp-edu29-pdf-en-finl.pdf?sfvrsn=2532d61b_2

Laboratory: Determination of toxins

• Chen J, Ling L, Liang S, Qu L, Li J, Zhang Y, Huang W, Huang L. Simultaneous determination of 12 lipophilic shellfish toxins in human plasma, serum, and urine using UPLC-MS/MS combined with PRiME HLBμElution platform. J Chromatogr A. 2025 Sep 27;1762:466418. Epub ahead of print. PMID: 41038079. https://doi.org/10.1016/j.chroma.2025.466418

Internet links providing specific information

Regional Centers 

• CDC  Atlanta

Species-specific evidence

Studies

Paralytic shellfish poisoning (PSP)
N: documented number of sick people in an outbreak ("epidemic").
n: number of sick people who were included in the documentation of the symptoms of poisoning.

Great Britain

• McCollum JP, Pearson RC, Ingham HR, Wood PC, Dewar HA. An epidemic of mussel poisoning in North-East England. Lancet. 1968 Oct 5;2(7571):767-70. PMID: 4175564. https://doi.org/10.1016/s0140-6736(68)90967-7
  Retrospective study. N = 78, n = 58. Toxin determination: mouse assay.

Switzerland (origin of the shellfish: Spain)

• Zwahlen A, Blanc MH, Robert M. Epidémie d'intoxication par les moules ["Paralytic shellfish poisoning" (author's transl)]. Schweiz Med Wochenschr. 1977 Feb 19;107(7):226-30. French.PMID: 836560.
  Retrospective study. N = ca. 120, n = 23.

Germany (origin of the shellfish: Spain)

• Simon B, Mebs D, Gemmer H, Stille W. Vergiftungserscheinungen nach dem Verzehr von Miesmuscheln [Poisoning after ingestion of mussels (mytilus edulis) (author's transl)]. Dtsch Med Wochenschr. 1977 Aug 5;102(31):1114-7. German.PMID: 891397. https://doi.org/10.1055/s-0028-1106714
  Retrospective study. N = ca. 120, n = 19. Identification of saxitoxin in shellfish samples (6,228–20,000 MU/100 g shellfish meat).

USA
Massachusetts

• Centers for Disease Control (CDC). Paralytic shellfish poisoning--Massachusetts and Alaska, 1990. MMWR Morb Mortal Wkly Rep. 1991 Mar 15;40(10):157-61. Erratum in: MMWR Morb Mortal Wkly Rep 1991 Apr 12;40(14):242. PMID: 1997833.
  N= 6. Identification of saxitoxin in shellfish that had not been eaten: 24,400 µg/100 g raw shellfish, 4,280 µg/100 g cooked shellfish (maximum concentration considered harmless: 80 µg/100 g).
  Erratum in

• MMWR Morb Mortal Wkly Rep 1991 Apr 12;40(14):242
  In the article "Paralytic Shellfish Poisoning -- Massachusetts and Alaska, 1990," the maximum safe level of saxitoxin concentration given in the third-to-last line of page 157 should be 80 ug/100 g.

Oregon

• Horowitz KM, Cowdery CP, Hendrickson RG. Clinical Features of Paralytic Shellfish Poisoning: a Case Series from the 2024 Oregon Outbreak. J Med Toxicol. 2026 Jan;22(1):39-43. Epub 2025 Nov 28. PMID: 41315144; PMCID: PMC12835469. https://doi.org/10.1007/s13181-025-01112-6

Guatemala

• Rodrigue DC, Etzel RA, Hall S, de Porras E, Velasquez OH, Tauxe RV, Kilbourne EM, Blake PA. Lethal paralytic shellfish poisoning in Guatemala. Am J Trop Med Hyg. 1990 Mar;42(3):267-71. PMID: 2316796. https://doi.org/10.4269/ajtmh.1990.42.267
  Retrospective study and case-control study. N = 187, n = 81–83. Inclusion criteria for determination of the size and characteristics of the outbreak: acute onset of illness with at least 2 symptoms (1 sensory, 1 non-sensory), occurring between 23 July and 7 August 1987. Inclusion criteria for the case-control study for the identification of risk factors: acute onset of illness, characterised by headache, hypaesthesia of 2 or more body regions and 2 or more of the following symptoms: vertigo, dysarthria, difficulty in standing from a lying or sitting position, dyspnoea. Toxin detection: mouse assay, saxitoxin identification in shellfish and in cooking stock (HPLC).

South Africa

• Popkiss ME, Horstman DA, Harpur D. Paralytic shellfish poisoning. A report of 17 cases in Cape Town. S Afr Med J. 1979 Jun 16;55(25):1017-23. PMID: 573505. 
  Outbreak investigation. N= 17. Toxin determination in shellfish samples (mouse assay).

Taiwan

• Cheng HS, Chua SO, Hung JS, Yip KK. Creatine kinase MB elevation in paralytic shellfish poisoning. Chest. 1991 Apr;99(4):1032-3. PMID: 2009759. https://doi.org/10.1378/chest.99.4.1032
  Outbreak investigation. N = 116, n = 5. Toxin determination in shellfish samples (gonyautoxins).

Signs and symptoms of PSP, NSP, DSP, ASP: comparison of various studies

(Review T. Junghanss)

 

Further studies and epidemiological investigations

PSP

Papua New Guinea 

• Rhodes FA, Mills CG, Popei K. Paralytic shellfish poisoning in Papua New Guinea. P N G Med J. 1975 Dec;18(4):197-202. PMID: 1066877.
  „An outbreak in a village near Port Moresby is described, and the clinical picture seen in that and subsequent cases (25 plus 3 fatalities) is discussed. The clinical manifestations of almost pure cerebellar incoordination, without other constant neurological signs, is emphasized and the name Ataxic Shellfish Poisoning is suggested.”
• G. K. WORTH, J. L. MACLEAN, AND M. J. PRICE. Paralytic Shellfish Poisoning in Papua New Guinea, 1972. Pacific Science 1975: 29, 1, 1-3

Case report (electrophysiology)

• Long RR, Sargent JC, Hammer K. Paralytic shellfish poisoning: a case report and serial electrophysiologic observations. Neurology. 1990 Aug;40(8):1310-2. doi: 10.1212/wnl.40.8.1310. PMID: 2381544. https://doi.org/10.1212/wnl.40.8.1310
  “We report serial electrophysiologic observations in a patient with acute bulbar and respiratory paralysis following ingestion of saxitoxin-contaminated clams. Prolonged distal motor and sensory latencies, slowed conduction velocities, and moderately diminished amplitudes were present at the outset. All values returned to normal over 5 days. These findings, the result of incomplete sodium channel blockade, distinguish paralytic shellfish poisoning from most other acute paralytic illnesses.”

For confirmed outbreaks see also

• James KJ, Carey B, O'Halloran J, van Pelt FN, Skrabáková Z. Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40. Epub 2010 Apr 23. PMID: 20412612. https://doi.org/10.1017/s0950268810000853
• Young N, Sharpe RA, Barciela R, Nichols G, Davidson K, Berdalet E, Fleming LE. Marine harmful algal blooms and human health: A systematic scoping review. Harmful Algae. 2020 Sep; 98:101901. Epub 2020 Sep 17. PMID: 33129458. https://doi.org/10.1016/j.hal.2020.101901

NSP

• Morris PD, Campbell DS, Taylor TJ, Freeman JI. Clinical and epidemiological features of neurotoxic shellfish poisoning in North Carolina. Am J Public Health. 1991 Apr;81(4):471-4. PMID: 2003627; PMCID: PMC1405066. https://doi.org/10.2105/ajph.81.4.471
  Retrospective cohort study. n = 48. Inclusion criteria: subjects were included in the study if, after consuming toxic shellfish, they developed one of the neurological symptoms that have previously been reported in connection with NSP (paraesthesia, reversal of temperature perception, myalgia, vertigo, ataxia) within 24 h after consuming the shellfish and for a duration of at least 1 h. Shellfish was considered toxic if it caused at least one case of poisoning according to the above-mentioned criteria and came from an area known to be a "red tide" region (>5,000 P. brevis organisms/litre water). Detection of P. brevis neurotoxins in shellfish samples.

For confirmed outbreaks see also

• James KJ, Carey B, O'Halloran J, van Pelt FN, Skrabáková Z. Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40. Epub 2010 Apr 23. PMID: 20412612. https://doi.org/10.1017/s0950268810000853
• Young N, Sharpe RA, Barciela R, Nichols G, Davidson K, Berdalet E, Fleming LE. Marine harmful algal blooms and human health: A systematic scoping review. Harmful Algae. 2020 Sep; 98:101901. Epub 2020 Sep 17. PMID: 33129458. https://doi.org/10.1016/j.hal.2020.101901

ASP

“The case definition was any individual who consumed mussels harvested from Prince Edwards Island River estuary after 1 November 1987, developed either gastrointestinal symptoms within 24 h, i.e., vomiting, diarrhea, and/or abdominal cramps, or at least one neurological symptom within 48 h, e.g., confusion, memory loss, disorientation, or other major objective sign, such as seizures, coma, or cranial nerve palsies. The ASP event included 107 documented and 38 probable cases. Eighteen percent of cases were hospitalized and half of these were in intensive care, with four deaths within 24 days. Seizures were found in the most severely poisoned individuals and became progressively less frequent over an eight-week period. Neurological batteries of tests on 14 of the most severe patients four months after poisoning identified a selective and severe impairment of anterograde memory in twelve individuals, peripheral neuropathy in eleven, and altered metabolic activity in the temporal lobes of four individuals. [15]. Three case studies describing different clinical features have been reported [16]” (Ramsdell and Gulland 2014; referring to the outbreak investigation of Perl et al 1990a,b and citing Teitelbaum et al 1990a[15], 1990b[16]).

• Teitelbaum JS, Zatorre RJ, Carpenter S, Gendron D, Evans AC, Gjedde A, Cashman NR. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N Engl J Med. 1990a Jun 21;322(25):1781-7. PMID: 1971710. https://doi.org/10.1056/nejm199006213222505
• Teitelbaum J. Acute manifestations of domoic acid poisoning: case presentations. Can Dis Wkly Rep. 1990b Sep;16 Suppl 1E:5-6.PMID: 2101741.
• Todd ECD. Domoic Acid and Amnesic Shellfish Poisoning - A Review. J Food Prot. 1993 Jan;56(1):69-83. PMID: 31084045. https://doi.org/10.4315/0362-028x-56.1.69  
• Perl TM, Bédard L, Kosatsky T, Hockin JC, Todd EC, Remis RS. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N Engl J Med. 1990a Jun 21;322(25):1775-80. PMID: 1971709. https://doi.org/10.1056/nejm199006213222504
  Retrospective study. N = 107. Inclusion criteria: occurrence of one or several gastrointestinal symptoms (vomiting, diarrhoea, abdominal cramps) within 24 h after the consumption of shellfish from King Edward Island on 1 November or later – or at least one of the following neurological symptoms within 48 h after the consumption of shellfish: confusion, amnesia, disorientation or other serious signs and symptoms, such as seizures or coma. Identification of the toxin responsible for the poisoning (domoic acid).
  Problems with the study: the documented 107 cases are probably an underestimation of the actual number of persons affected, with the most under-represented being those with solely gastrointestinal symptoms. The study was based on a questionnaire, and thus the range of symptoms included was limited by the questions asked.

For confirmed outbreaks see also

• James KJ, Carey B, O'Halloran J, van Pelt FN, Skrabáková Z. Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40. Epub 2010 Apr 23. PMID: 20412612. https://doi.org/10.1017/s0950268810000853
• Young N, Sharpe RA, Barciela R, Nichols G, Davidson K, Berdalet E, Fleming LE. Marine harmful algal blooms and human health: A systematic scoping review. Harmful Algae. 2020 Sep; 98:101901. Epub 2020 Sep 17. PMID: 33129458. https://doi.org/10.1016/j.hal.2020.101901

Diarrhoetic shellfish poisoning (DSP)

• Yasumoto, T., Y. Oshima, M. Yamahuchi (1978) Occurence of a new type of shellfish poisoning in the Tohoku District. Bull. jap. Soc. sci. Fisheries 44: 1249-1255
  Retrospective study (first documented DSP epidemic). N = 164. Toxicity investigations in a mouse assay. Toxin that causes DSP not yet isolated.

For confirmed outbreaks see also

• James KJ, Carey B, O'Halloran J, van Pelt FN, Skrabáková Z. Shellfish toxicity: human health implications of marine algal toxins. Epidemiol Infect. 2010 Jul;138(7):927-40. Epub 2010 Apr 23. PMID: 20412612. https://doi.org/10.1017/s0950268810000853

• Young N, Sharpe RA, Barciela R, Nichols G, Davidson K, Berdalet E, Fleming LE. Marine harmful algal blooms and human health: A systematic scoping review. Harmful Algae. 2020 Sep; 98:101901. Epub 2020 Sep 17. PMID: 33129458. https://doi.org/10.1016/j.hal.2020.101901