Health officials identified legionella bacteria in a whirlpool spa at the Playboy Mansion in Los Angeles during an investigation in February that began when people were sickened after attending a fundraiser.

The Los Angeles Times reports a number of people came down with a respiratory illness after DomainFest’s Feb. 1-3 conference, which culminated in a fundraiser at the Playboy Mansion in the Holmby Hills area of Los Angeles. Officials investigated to see if legionellosis was at fault; the more severe version of that illness is known as Legionnaires’ disease, while a milder version is called Pontiac fever.

Out of 439 people contacted by L.A. County public health officials, 123 fell sick with fever and at least one other symptom, such as headache, cough, shortness of breath, or aches. Sixty-nine people got sick on the same day, Feb. 5.

Health investigators used blogs, Twitter and Facebook and had an online survey sent to all 715 conference attendees, who had traveled from 30 countries, to determine the extent of the outbreak. Seventy-nine people said through social media that they were ill.

The results were made public Friday in a presentation by L.A. County health officials at the U.S. Centers for Disease Control and Prevention’s annual Epidemic Intelligence Service conference in Atlanta.