The original number of cases of Legionellosis reported by the Centers for Disease Control and Prevention (CDC) for calendar year 2018 was already at a record 8,356 cases. This November, that number was revised upward to 9,933 cases, representing an increase of 18.8 percent . Although Legionellosis includes both Legionnaires’ disease and Pontiac fever, the vast majority of these newly reported cases were for the more serious diagnosis of Legionnaires’ disease.