Legionnaires' disease outbreak

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The Infectious Diseases Unit of the Human Services Department, Victoria, has received five notifications of Legionnaires' disease, with onset of symptoms in late June and early July. All cases either lived or worked in the same suburban area, and were due to Legionella pneumophila serogroup 1. One death, in an elderly woman, was reported on 30 June. Investigations found two air conditioning cooling towers close to the suburban shopping district were positive for the same Legionella pneumophila serogroup. One of these towers tested positive for the same molecular sub-type as that found in sputum specimens from two of the cases, one of the cases had a different molecular sub-type, and no bacterial cultures were available from the other two cases. The towers have since been closed, disinfected and reopened, and the associated organisations have been given written recommendations on further treatment to avoid reinfection.

Although there had been 29 other cases with four deaths in Victoria for the year, earlier cases were sporadic in nature. Due to the proximity in reporting time and location, and the usual low incidence for this time of year, these recent five cases were considered to be a cluster. There are usually about 20 to 40 cases of Legionnaires' disease per year in Victoria.

This article was published in Communicable Diseases Intelligence Vol 22 No 8, 6 August 1998.