Staff members from the Centers for Disease Control based at the department were assisting with the investigation, the statement said, but those at CDC headquarters in Atlanta have not yet been enlisted, said CDC spokeswoman Alison Patti.

"The department is investigating several locations associated with this conference, including the Playboy Mansion in Holmby Hills," the statement said. "At this time, Public Health has not determined that the source of exposure is limited to a specific location. The department is working to conclusively identify the source of exposure and the likely cause of illness for this suspected outbreak."

The department was notified last Friday of a "suspected respiratory infection outbreak" among those associated with the conference, and officials were still identifying and contacting possible victims Monday, according to the statement.

The possible outbreak of legionellosis, or Pontiac fever, affected people connected with the Feb. 3 DOMAINfest Global Conference in Santa Monica, "with symptoms mostly consisting of fever, chills, general discomfort (malaise) and some cough," according to a statement Monday by the county Department of Public Health.

Los Angeles County health officials said Monday that 170 people have fallen ill after attending or working at a fundraiser at the Playboy Mansion , but they do not believe the outbreak has spread beyond those associated with the event.

"As a number of conference attendees live outside of Los Angeles County, Public Health is working with surrounding county health departments, the California Department of Public Health, and the Centers for Disease Control and Prevention (CDC) in this investigation," the statement said. "Public Health has no information suggesting that this suspected outbreak extends beyond those individuals associated with this conference."

It was not clear how soon investigators could determine whether the illness is legionellosis, a milder form of Legionnaires' disease caused by a bacterium that grows in warm water and can take root in hot tubs or parts of air-conditioning systems, according to the CDC.

"It is a lengthy process; there are a lot of people involved that we need to talk to," said Sarah Kissell, a spokeswoman.

Patti confirmed that although testing for legionellosis can be performed within a week, it takes longer to track down those potentially affected and get them tested.

Ron Jackson, editor and publisher of DNJournal.com, attended the conference with his wife, including the Playboy Mansion event, and said he knows of at least one attendee from Sweden who was later told by a doctor that he had contracted legionellosis.

Jackson did not fall ill, but his wife did. He said he has been in contact with Dr. Caitlin Reed of the CDC, who is working with county health officials. He also compiled a sick list that includes at least 97 conference attendees. Jackson said he was particularly concerned about models hired to attend the Playboy Mansion event.

"I am not aware of anyone being sick who was not at the conference — but there would be no reason for anyone to contact me about that, as all of the articles have been about people who fell ill after attending," Jackson said in an e-mail Monday. "Dr. Reed told me they do have the list of models' names and have contacted them. One of those models also contacted me and said she had been sick."

Spokeswomen for Playboy and the Fairmont Miramar Hotel in Santa Monica, where the conference was held, did not return phone calls Monday.

David Castello, who cofounded Castello Cities Internet Network Inc. with his brother, Michael, said he became ill after attending the conference and fundraiser.

Although some have blamed a fog machine at the Playboy party, because legionellosis is a water-borne illness, Castello was waiting for definitive results from county health officials.

“I’d like to know what took away a week of my life,” said Castello, who said he still felt weak Monday as he prepared to leave for a conference in Uruguay. “They just need to find out where and when it started. Now it’s like a big mystery — everyone wants to know.”

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