Dozens of people said they became sick after attending a fundraiser that was held on Hugh Hefner's famous grounds in Holmby Hills on Feb. 3. The event was part of the DOMAINfest Global Conference held in Santa Monica at the Fairmont Miramar Hotel.
L.A. County Health officials began an investigation after several people started to complain of fever.
The source of the illness has yet to be determined. The Health Department said it is still too early to tell what the outbreak may be or how it started, but many who attended the Playboy party suspect a faulty fog machine may be to blame.
Playboy officials say they are cooperating with the county's investigation.
Aside from the Playboy Mansion, officials are also looking into the Fairmont Miramar Hotel, another gathering spot for last month's conference.