(Portland, OR) -- At least 20 people have been sickened after eating mussels they gathered at Short Beach near Oceanside, Hug Point, and near Seaside. Oregon Fish and Wildlife has shut down mussel harvesting from Washington to Seal Rock State Park because high levels of a naturally occurring biotoxin has been found in mussels. The Oregon Health Authority says anyone with mussels harvested from that area should throw them away. Anyone experiencing symptoms after eating mussels that include numbness of the mouth and lips, nausea, vomiting, diarrhea, weakness and in severe cases shortness of breath or irregular heartbeat should immediately get medical help.