LEGIONNAIRES-DISEASE OUTBREAK, FAIRFIELD 1992 - PUBLIC-HEALTH ASPECTS

An investigation of an outbreak of Legionnaires' disease in 1992 in Fa irfield, a municipality of Sydney, was carried out to determine the so urce of the outbreak. Cases of Legionnaires' disease with onset of sym ptoms between 11 and 20 April 1992 were included. Definite cases were individuals with a history consistent with Legionnaires' disease, conf irmed by direct fluorescent antibody testing plus serology or culture. There were two control groups: patients admitted to the same hospital as the cases, matched for age and sex, and patients admitted to hospi tal with a presumptive diagnosis of Legionnaires' disease, in whom the diagnosis was subsequently excluded. There were 26 definite cases wit h onset of symptoms between 11 and 20 April 1992. Six (23 per cent) di ed. Twenty-two cases (85 per cent) reported visiting the Fairfield bus iness district during the ten days prior to the onset of symptoms. The y were 20 times more likely to have visited Fairfield than were matche d controls. Matching of Legionella pneumophila serogroup 1 from enviro nmental and clinical samples was achieved by cytogenetic fingerprintin g. Fourteen cases were linked to a single environmental sample. The ep idemiological findings were consistent with a point source of Legionel la in the Fairfield business district. It is most likely that the expo sure occurred on 10 April 1992.