Up to 200 people attending a conference and fundraiser in Southern California have developed symptoms suggestive of Legionellosis (“Legionnaire’s Disease). Moreover, the bacterium, of the Legionella genus, has been isolated from a water source at the Playboy Mansion , where the fundraiser was held, providing a putative source of common exposure. Symptoms typically include fever, chills, nonproductive cough which can later become productive, lower respiratory involvement including pulmonary symptoms including pneumonia, and other non-specific findings. Specific identification is typically by antibody testing, a urine test in the case of the most common pathogen, L. pneumophila (only serotype 1) , and isolation and culture of the bacterium. The case fatality ratio can be highly variable, depending upon the species involved, the rapidity of recognition and rapid identification and treatment of patients, and perhaps the virulence of the specific organism. There are a number of effective antibiotics, including quinolones (eg levofloxacin), macrolides (eg azithromycin), and both are sometimes used with rifampin. In the originally identified outbreak in 1976, erythromycin was the antibiotic that was found to be efficacious–at the time, the fluoroquinolones had not yet been approved, and azithromycin had not been developed.