The Department of Public Health in Los Angeles County contacted dozens of people who attended the annual DOMAINfest Global conference in Santa Monica this month, telling them it received reports of flu-like respiratory illnesses among attendees, some of whom also attended an event at the Playboy mansion, the Los Angeles Times reported.
"An investigation into the cause and extent of illness and into potential sources of exposure is ongoing," said Sarah Kissell, a health department spokeswoman.
The event was held at the Fairmont Miramar Hotel in Santa Monica, but a Feb. 3 fundraiser was held at Hugh Hefner's famous estate.
A Swedish attendee tested positive for the Legionella bacterium when he returned home and some of those who fell ill said they suspected a fog machine may have spread the illness. Legionnella is a milder form of Legionnaire's disease.
The event's organizer urged attendees not to make assumptions and to await the outcome of the investigation.
"Only medical authorities are qualified to identify this illness and investigate its ultimate source. ... It's important not to speculate or make unfounded assumptions," said Mason Cole, organizer of the conference.