There are around 6,000 Legionnaires' disease cases are reported each year in the United States. However, scientists believe the reported totals are much lower than the actual cases due in part to the difficulty in distinguishing Legionnaires' disease from other types of pneumonia. The most recent U.S. population-based study estimated that 8,000-18,000 people are hospitalized each year with Legionnaires' disease, according to the Occupational Safety and Health Administration (OSHA).

Additionally, about one in 10 people who get sick from Legionnaires’ disease will die, per the Centers for Disease Control and Prevention (CDC). There is no vaccination to prevent Legionnaires’ disease, therefore, the best way to control the spread is to prevent the growth of Legionella pneumophila in plumbing systems.