A confirmed case of paralytic shellfish poisoning last week has prompted epidemiologists with the Alaska Department of Health and Social Services to remind Alaskans and visitors about the risk of paralytic shellfish poisoning, or PSP, when consuming recreationally harvested Alaska shellfish. All shellfish — including clams, mussels, oysters, geoducks and scallops — can contain paralytic shellfish poison. Crabmeat is not known to contain the PSP toxin, but crab guts can contain unsafe levels of toxin and should be discarded. Commercially harvested shellfish are tested and considered safe.
The confirmed case last week involved a mixture of clams (horse, manilla, and butter) harvested from a beach north of Ketchikan the week of April 20, consumed the evening of April 24. The patient experienced typical symptoms of PSP within 30 minutes of consumption. Early signs of poisoning include tingling of the lips and tongue. Symptoms may progress to tingling of fingers and toes, then loss of control of arms and legs, followed by difficulty breathing. Death can result in as little as two hours.
Fortunately, this patient did not experience severe symptoms. Clams leftover from the meal were tested at Alaska’s Department of Environmental Conservation Environmental Health Laboratory and found to contain markedly elevated levels of saxitoxin (1,090 µg per 100 grams of meat). The regulatory limit is 80 µg per 100 grams.
Although clam diggers often look for signs of a “red tide,” there is no way to tell if a beach is safe for harvesting simply by looking at it. The toxins that cause PSP can be present in large amounts in shellfish even if the water looks clear and no algae bloom is present. Additionally, PSP cannot be cooked, cleaned or frozen out of shellfish. The Alaska Division of Public Health fact sheet on PSP can be found at:http://www.epi.alaska.gov/id/dod/psp/ParalyticShellfishPoisoningFactSheet.pdf
Paralytic shellfish poisoning is considered a public health emergency. Suspected cases must be reported immediately to the Section of Epidemiology by health care providers at 907-269-8000 during work hours or800-478-0084 after hours. For more information on PSP go to: http://www.epi.hss.state.ak.us/id/dod/psp/default.htm