Health officials now know what sickened dozens of people in Visalia.
It was an outbreak of the norovirus at the Visalia Country Club.
51 people who visited the club became ill over the weekend, suffering from vomiting and nausea.
Health officials say the norovirus can be spread from contaminated food, person-to-person contact, and from contaminated surfaces.
The club was closed while decontamination efforts are underway.
The golf coarse is still open and they expect to reopen the club on Sunday or Monday.
Norovirus infection is characterized by nausea, forceful vomiting, watery diarrhea, and abdominal pain and affects people of all ages.