State public health officials have issued warnings against recreational harvesting of mussels, clams and other bivalve shellfish from San Mateo to Marin counties because of potentially lethal levels of a naturally occurring toxin.

Marin County health officials said Wednesday they were notified the day before that mussel samples from the Chimney Rock sentinel station within the Point Reyes National Seashore were recently found to contain 37 times the “alert” level of paralytic shellfish poison, or PSP.

The warnings did not specify whether shellfish recreational harvesting off the Sonoma Coast was also affected. State public health officials could not be reached Wednesday to determine when the last testing was done in Sonoma County.

The advisories do not apply to commercially harvested shellfish.

Sonoma County public health officials who distributed a Marin County advisory Wednesday said they had no current information suggesting local contamination.

The marine toxin causes illness after someone eats contaminated shellfish.

Marin County Public Health Officer Matthew Willis said in a statement Wednesday that “anyone who experiences tingling, numbness, headaches, dizziness, nausea, rapid pain or respiratory problems after ingesting any type of shellfish recently should seek medical attention immediately.”

Officials said changes in water temperature, flow and salt content can lead to sudden increases in PSP levels. The toxin cannot be eliminated by cooking the shellfish.

The National Park Service has been asked to post warning signs at locations along Drakes Bay within the Point Reyes National Seashore, Willis said.

The state public health warning does not apply to clams, mussels, scallops or oysters harvested and sold commercially, as these are subject to frequent mandatory testing.

For the most recent information on shellfish advisories, call the state’s toll-free shellfish information line at 800-553-4133.

You can reach Staff Writer Martin Espinoza at 707-521-5213.