On "The Early Show," CBS News National Correspondent Ben Tracy reported authorities are still tracking down everyone who attended the convention at the Playboy mansion -- one of prime locations suspected for sparking this outbreak.
Tracy reported 700 Internet conventioneers from 30 countries were invited to the lavish fundraising party at the legendary location.
Barbara Neu, who attended the convention, said, "Who hasn't wanted to go to Hugh Hefner's Playboy mansion?"
But within 48 hours of the Feb. 3 event, dozens fell ill with extreme, flu-like symptoms, such as coughs, fever, chills and respiratory infections. The symptoms, Tracy reported, wouldn't go away. The number has grown to at least 170.
David Castello, who also attended the event, said, "I'm very fatigued. It wiped me out very quickly."
Howard Neu, who was sickened after the event, told CBS News, "I could hardly lift my head up. I was up and down the whole night with night sweats, coughing, choking."
The Los Angeles County Department of Health is investigating the Playboy mansion, but has not yet identified it as the source of the outbreak. They do suspect the illness is a mild form of Legionnaires' disease, also known as Pontiac fever.
Dr. Stephen Jones, of Northridge Hospital Medical Center in Northridge, Calif., said, "A whole bunch of people get sick real quickly; that's what gives you the clue that this is something other than just the flu that's being passed from person to person."
Barbara Neu and her husband, Howard, haven't been able to kick the illness. At first, they blamed cold weather poolside. Now they believe the culprit was the party tent's fog machine, since the disease can be transmitted through evaporated water.
Neu said, "You could see the fog in the air, and it was constantly blowing everybody was sitting right there in it."
Tracy added another reason authorities are focusing on the Playboy mansion is because the disease has not spread beyond the conventioneers who were there two weeks ago. Playboy Enterprises is cooperating with the investigation.
CBS News Medical Correspondent Dr. Jennifer Ashton explained on "The Early Show" that, when so many people get sick in such a short period of time who were all in the same area, medical investigators have to look for a "unifying feature."
"This sounds like a history lesson, but Legionnaires' disease really refers to a bacteria called legionella bacteria, and it typically causes upper respiratory infections that, in the case of Legionnaire's disease, could be fatal. In the case of Pontiac's disease, it really is a much milder form -- usually self limited."
She continued, "This bacteria is found in soil, but it's also found in wet, moist environments. So that could be hot tubs, large ventilation or air conditioning systems -- even shower heads. So it's very easily transmitted through respiratory droplets or in the air, not spread person to person, so it's not direct contact, but anytime you're inhaling the same air system, this is something that's on the top of the list."
She said symptoms start 24 to 48 hours after exposure.
"You can see anything from headaches to muscle aches to chills, high fever, usually over 104 degrees. In a milder form like Pontiac's disease, you might have milder forms of these symptoms, but again, not subtle, they usually come on really, really strong and typical upper respiratory symptoms."
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When it comes to treatment, Ashton said the milder form of Legionnaires' disease runs its course without treatment. In more severe cases, she said antibiotics and sometimes hospitalization with ventilator support is necessary.