Community-acquired legionellosis in Singapore.

Patients admitted to hospital with chest infections were examined serologically to see if these were due to Legionella pneumophila. Each of the 219 samples of serum collected from 177 patients was examined by two standard tests. The tests, which generally agreed, identified three individuals (1.7% of the group) who had sufficient antibody to suggest that they were suffering from current legionellosis. Serological evidence of previous infection was discovered (with differing degrees of certainty) in 26 (14.7%) of the others. The study showed that legionellosis is endemic in Singapore, and so must be taken into account in the differential diagnosis of cases of pneumonia.