The California Department of Public Health on Wednesday issued a health advisory warning people not to eat sport-harvested mussels, clams or whole scallops from four counties in Northern and Central California.

Mussels from San Francisco, San Mateo, Santa Cruz and Monterey counties were found to contain dangerous levels of paralytic shellfish poisoning toxins, KTLA sister station KRON in San Francisco reported.

The toxins affect the central nervous system and can leave those who eat the toxic shellfish with a tingling sensation around the mouth and fingertips, health officials. The symptoms are then typically followed by loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing.

In severe cases, the toxins can cause complete paralysis or even death from asphyxiation.

The Health Department said cooking the shellfish would not get rid of the toxins. 

The health advisory warning does not apply to commercially sold clams, mussels, scallops or oysters from approved sources.

“Shellfish sold by certified harvesters and dealers are subject to frequent mandatory testing to monitor for toxins,” the agency’s health advisory said.