The Los Angeles Times said 3,500 people, including guests at a party for Sports Illustrated's swimsuit issue, may have been exposed to the illness at recent events.
The alert involves 13 events from Feb. 3-20 that the infected cook worked on, the newspaper said. The cook has not been involved with the Wolfgang Puck restaurant, cafe or prepared food divisions, officials said.
Dr. Jonathan Fielding, Los Angeles County's director of public health, said the risk of contracting the communicable disease --the least serious of the viral forms of hepatitis-- is low.
Medical authorities, however, are urging people who ate uncooked food at four catered events Feb. 14-20 to receive shots of immune globulin to prevent onset of the disease.
The newspaper said singer-actress Beyoncé and other swimsuit models attended the Sports Illustrated event.