1976 Philadelphia Legionnaires' disease outbreak States Center for Disease Control and Prevention (CDC) in 2017 only use the term Legionnaires' disease to refer to the serious version with pneumonia. CDC investigators quickly discovered outbreaks of respiratory disease caused by "L. pneumophila" dating back to 1959. An outbreak of what was dubbed Pontiac fever occurred in a health department in Pontiac, Michigan in July 1967. No one died. Although caused by the same bacterium, Pontiac fever is a milder ailment than Legionnaires' disease. Pneumonia is absent in those with Pontiac fever. An outbreak of pneumonia in July–August, 1965, at St. Elizabeths Hospital in Washington, DC, which
Hospital-acquired pneumonia white cell count (leukocytosis), the prognosis seems to be influenced by the underlying associated diseases (comorbidities) and functional capacities (for example, the ADL score). Many patients have a decreased health condition after the episode. Several studies found that healthcare-associated pneumonia is the second most common type of pneumonia, occurring less commonly than community-acquired pneumonia but more frequently than hospital-acquired pneumonia and ventilator-associated pneumonia. In a recent observational study, the rates for CAP, HCAP and HAP were 60%, 25% and 15% respectively. Patients with HCAP are older and more commonly have simultaneous health problems (such as previous stroke, heart failure and