Paralytic Shellfish Poisoning (PSP) is a severe and potentially fatal form of seafood poisoning caused by consuming shellfish contaminated with neurotoxins. These toxins are produced by microscopic marine algae (dinoflagellates) during harmful algal blooms, often called \"red tides.\" It primarily affects people who eat contaminated bivalve shellfish like clams, mussels, oysters, or scallops.
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Paralytic Shellfish Poisoning has been documented for centuries, with early indigenous coastal communities recognizing its dangers. The scientific link between shellfish consumption and neurological symptoms was established in the late 19th and early 20th centuries. Further research in the mid-20th century identified the causative neurotoxins, such as saxitoxin, and their origin in certain marine dinoflagellates.
Paralytic Shellfish Poisoning is not transmitted directly from person to person. It is acquired solely through the consumption of shellfish (bivalve mollusks like mussels, clams, oysters, and scallops) that have fed on and accumulated toxins from specific species of microscopic marine algae. These algae produce potent neurotoxins that become concentrated in the shellfish's tissues without harming the shellfish themselves.
Contagious Period: Varies by disease
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Affected shellfish include bivalve shellfish such as mussels, oysters, tuatua, pipi, toheroa, cockles and scallops, as well as pΕ«pΕ« (cat's eyes) and Cook's turban.
"Cooking the shellfish does not remove the toxin, so shellfish from this area should not be eaten," Arbuckle said.
Symptoms of paralytic shellfish poisoning usually appear within 10 minutes to three hours of eating and may include:
numbness and a tingling (prickly feeling) around the mouth, face, hands, and feet
paralysis and
π° 15 news sources reporting on this story.
Thirty-three cases of paralytic shellfish poisoning occurred in coastal Guangdong Province following consumption of okadaic acid-contaminated conchs, with all patients experiencing mild to moderate symptoms and no fatalities. This pre-Spring Festival outbreak highlights ongoing risks from heat-resistant shellfish toxins along China's southern coast, where seasonal red tide algae proliferation creates persistent contamination hazards during peak shellfish consumption periods.
Source: BEACON - View Full Report
Public health authorities on the West Coast have issued a warning against consuming shellfish after a harmful algal bloom was detected. These blooms can produce toxins that cause severe illness, including potentially fatal paralytic shellfish poisoning. Residents are advised to immediately avoid harvesting or consuming shellfish from affected areas.
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View WHO Resources βDisease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.
Last reviewed: 2026-06-03
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