Epidemiology

Poisoning from marine toxins has been described worldwide and is increasing due to global warming, growing seafood consumption and the spread of toxic algal blooms.[2][3]

Saxitoxin exposure

  • Contaminated shellfish containing saxitoxin can be found in temperate and tropical waters, but especially in the Pacific Northwest.

  • Outbreaks can occur during blooms of toxic algae, especially dinoflagellates of the genus Alexandrium, as feeding shellfish concentrate the toxin and are unsafe to consume.[4]

  • In 2020, the US Centers for Disease Control and Prevention documented 227 instances of harmful algal blooms in the US, with five cases specifically indicating the presence of saxitoxins.[5]

Tetrodotoxin exposure

  • Common in Japan, Taiwan, Southeast Asia, and Australia due to geographical proximity of the puffer fish and blue-ringed octopus.

  • Cases have been sporadically reported across the US, but were due to imported puffer fish from endemic areas.[6]

  • Tetrodotoxin has been detected sporadically in shellfish in Europe and one poisoning was reported in Spain, but the risk to public health is unclear.[7]

Conotoxin exposure

  • Conotoxins are a group of toxins in the venom of cone snails.[8]

  • Conotoxin-producing cone snails thrive in tropical marine habitats in the Pacific and Indian oceans.[9] Nocturnally active, cone snails are often found in shallow water under rocks, crawling along beaches, and within reefs.[10]

Epidemiological data for marine toxin poisoning are rare and are likely to be underestimated owing to factors such as regional variations in required reporting and lack of diagnostic testing. Therefore, prevalence and incidence data for marine intoxications are likely to be underestimated. Published epidemiological data tend to be from case reports from a particular locale during an outbreak; for example, the state of Alaska reported 117 cases of paralytic shellfish (saxitoxin) poisoning in 54 separate outbreaks over a 20-year period from 1973 to 1992.[11] Between 1998 and 2002, there were a further seven outbreaks reported in the US with a total of 43 cases.[12]​​

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