Bacteria that cause Legionnaires' disease were found at the Playboy Mansion during an investigation into an illness that affected about 200 people who attended an event there last month, a health official said.
Other infection sources have not been ruled out as the cause of the illness because the bacteria Legionella is common in moist places, Los Angeles County Department of Public Health director Dr Jonathan E Fielding said.
"We are still considering several possible causes of illness," Fielding said.
County health officials opened an investigation on February 11 after attendees of an internet conference reported symptoms mostly consisting of fever, chills, malaise and coughing.
Playboy did not immediately respond to requests for comment.
The DOMAINfest Global Conference took place on February 1-3 with events at several hotels and a fundraiser at the Holmby Hills estate where Playboy founder Hugh Hefner resides.
Health officials have not ordered occupants to leave the mansion.
About 700 people from 30 countries attended lectures and workshops at the conference. The county is investigating the outbreak with state and federal health officials to track illness outside Los Angeles.
Health officials declined to comment on where the bacteria were discovered at the mansion, calling it only a water source. That could mean anywhere from a tap to the grotto, where Playboy bunnies have mingled with guests in a hot tub.