Epidemiological investigation on an outbreak of Legionnaires' disease associated with contaminated air conditioner in a hospital

Abstract

Objective To understand an epidemic outbreak caused by Legionella pneumophila infection, and provide scientific basis for prevention and control measure. Methods The cases and environment from an outbreak of Legionnaires' disease in one hospital in 2013 were surveyed by retrospective investigation and field epidemiological investigation. Legionella pneumophila was identified by polymerase chain reaction assays and enzyme-linked immunosorbent assays. Results Six patients with unexplained pneumonia were all hospital workers, including 1 male patient and 5 female patients. The clinical manifestations were fever, muscle aches, cough, headache, fatigue, etc. Out of 6 urine samples, 3 samples were positive. Legionella pneumophila was detected in cooling water and dust specimens from air conditioner. Conclusions The evidence shows that it is an outbreak resulting from air conditioner contaminated by Legionella pneumophila. The air conditioning in densely populated sites should be cleaned and disinfected professionally and regularly, in order to reduce the risk of Legionella pneumophila infection and transmission at the maximum limit. Key words: Legionnaire's disease; Air conditioner; Outbreak; Epidemiological investigation