Legionnaires Disease & Pontiac Fever Outbreak in a City Garage: A Retrospective Cohort Study

Objective: Determine if an outbreak of Legionella pneumophila was associated to the city garage.

Background: In 2004 the Cleveland Department of Public Health received a report from a community member of individuals that worked in a city garage that were ill and hospitalized from Legionnaires Disease. One month following this account the Health Department received an additional report of a Legionnaires Disease case associated with a city garage. It was determined that these two cases were confirmed Legionnaires Disease cases through additional investigation.

Method: A retrospective cohort study was done to determine whether there was an association between environmental factors and illness. There were forty one participants in the outbreak study. Results: There were 18 environmental factors tested epidemiologically and environmentally. One of the hypotheses proposed indicated there is a significant association between sitting in the patio area near the steam jenny and legionnaire's disease or pontiac fever. This hypothesis was weakly associated p=.08. Additional sampling done on the water sources also yielded legionella, however isolates were unable to be sub typed and matched to the index case patient.

Discussion: It is often difficult to determine how individuals were exposed to legionella pneumophila. Although this outbreak is associated to the city facility in question it is often difficult to isolate the source on legionnaires due to the aspect of the pathogen and that it is sporadic in the environment as a whole.