Unalaska, AK – A possible case of paralytic shellfish poisoning in Unalaska has health officials reiterating a warning against eating certain shellfish from local waters.

Rebecca Sheffield, the state Department of Environmental Conservation's environmental health officer in Unalaska, said she received a report of an Unalaska resident "who dug some razor clams out at Summer Bay, went home and cooked them up, and then a few hours later after they ate them, they started feeling ill." Sheffield said she didn't know who was infected.

Paralytic shellfish poisoning, or PSP, can happen when you eat shellfish containing a certain toxin that clams and mussels accumulate by consuming microorganisms called dinoflagellates. Sheffield said signs of poisoning--numbness in the lips, mouth and tongue, shortness of breath and vomiting--are easy to spot.

"You feel really bad," she said. "It can come on as quick as 20 minutes, or a couple of hours after you consume the seafood."

Although the effects vary, Sheffield said it is possible to get a fatal dose of PSP from a single clam. She said it's important to remember that you can be poisoned by the meat even if it's been cooked or frozen.