The state Department of Public Health issued a warning against the largest oyster producer in California on Friday.
After eating in separate San Francisco restaurants last month, three people came down with illnesses linked back to oysters from Drakes Bay Oyster Company.
The company shut down all operations after being notified by the Health Department that its oysters may be contaminated with Vibrio parahaemolyticus, a naturally occurring bacterium that can cause serious illness, manager Ginny Cummings told the Oakland Tribune.
No other illnesses have been reported, but the oyster farm, which supplies almost 40 percent of California's shellfish, has begun a voluntary, precautionary recall of its in-shell and shucked oysters.
"As a family business, we're doing the best we can do under the circumstances, which is a waiting game at this point," Cummings said. "We're working hand-in-hand with the health department on this. Our biggest concern is that people are healthy."
Grub Street reported that the possibly infected packages have lot numbers ranging from 363 through 421. The lot number can be found on the top label of each jar or tub. Oysters marked with harvest dates ranging from July 17 to August 8 should also be thrown out.
According to the Center for Disease Control and Prevention, symptoms of Vibrio parahaemolyticus infection include "diarrhea often with abdominal cramping, nausea, vomiting, fever and chills." Symptoms generally occur within 24 hours of ingestion and subside without treatment in about three days.
A complete list of the recalled products and photos of the shellfish tags and labeling is on the department of public health website.