Lake County General Health District confirmed samples that were collected at the Kirtland Country Club were tested positive for norovirus.
The Kirtland Country Club received reports of people being ill from individuals that had attended events on the weekend of May 13.
Lake County Health Commissioner Ron Graham said in a news release that it's unlikely that any one person or thing will be identified as the source of the virus.
Norovirus is a highly contagious virus that causes inflammation of the stomach and intestines. The most common symptoms include diarrhea, vomiting, nausea and fever.
The number of individuals ill and hospitalized remains unconfirmed at this time.