Outbreak of legionellosis in a community. Report of an ad-hoc committee.

Of 33 patients infected in an outbreak of legionellosis in Glasgow in 1984, 26 lived in the Dennistoun district and the remainder either worked in or visited there. There were three main clusters of cases, the onset of illness being in early and mid June in two clusters and early September in the third. Most patients were not severely ill, but 1 patient died. The likely source of infection was a cooling tower from which Legionella pneumophila serogroup 1 was isolated. Strains indistinguishable from the cooling-tower strain were isolated from 2 of the patients. Cases occurred downwind of this cooling tower up to a distance of 1700 m. It is suggested that airborne infection with L pneumophila may extend further from the source than has hitherto been recognised.