A Large Outbreak of Legionnaires??? Disease at a Flower Show, the Netherlands, 1999

A LARGE OUTBREAK OF LEGIONNAIRES’ DISEASE AT A FLOWER SHOW, THE NETHERLANDS, 1999 [Den Boer JW et al. Emerg Infect Dis 2002;8:37]: The authors report the observations of an outbreak of Legionnaires’ disease among visitors to a flower show in the Netherlands in 1999. The source of the outbreak presumably was two whirlpool spas; both were culture positive for a strain of L. pneumophila serogroup one, which was identical by genotype to isolates in 28 of 29 culture positive patients. The total number of cases was 188 including 133 that were confirmed (positive culture, positive urinary antigen assay or four fold rise in titer) and 55 were probable (pneumonia during the risk period, but without laboratory confirmation). Other observations are summarized in Table 7.TABLE 7: Legionnaires’ Disease: Flower Show, NetherlandsComment. This apparently is the second largest reported outbreak of Legionnaires’ disease since the original report in 1976 in Philadelphia, which included 221 cases. As with other outbreaks, most of the patients were in their advanced years, the disease was severe with 21% requiring mechanical ventilation, and the mortality rate was 11%. Analysis of risk factors showed the odds ratio for smokers was 6.0, again agreeing with prior reports.