Abstract
BackgroundFinnish and Swedish waste water systems used by the forest industry were found to be exceptionally heavily contaminated with legionellae in 2005.Case presentationWe report two cases of severe pneumonia in employees working at two separate mills in Finland in 2006. Legionella serological and urinary antigen tests were used to diagnose Legionnaires' disease in the symptomatic employees, who had worked at, or close to, waste water treatment plants. Since the findings indicated a Legionella infection, the waste water and home water systems were studied in more detail. The antibody response and Legionella urinary antigen finding of Case A indicated that the infection had been caused by Legionella pneumophila serogroup 1. Case A had been exposed to legionellae while installing a pump into a post-clarification basin at the waste water treatment plant of mill A. Both the water and sludge in the basin contained high concentrations of Legionella pneumophila serogroup 1, in addition to serogroups 3 and 13. Case B was working 200 meters downwind from a waste water treatment plant, which had an active sludge basin and cooling towers. The antibody response indicated that his disease was due to Legionella pneumophila serogroup 2. The cooling tower was the only site at the waste water treatment plant yielding that serogroup, though water in the active sludge basin yielded abundant growth of Legionella pneumophila serogroup 5 and Legionella rubrilucens. Both workers recovered from the disease.ConclusionThese are the first reported cases of Legionnaires' disease in Finland associated with industrial waste water systems.
Highlights
Finnish and Swedish waste water systems used by the forest industry were found to be exceptionally heavily contaminated with legionellae in 2005.Case presentation: We report two cases of severe pneumonia in employees working at two separate mills in Finland in 2006
Following Swedish reports of extremely high concentrations of legionellae in biological waste water treatment plants and Legionnaires’ disease (LD) in an employee working near a plant [7], an environmental study was initiated focusing on waste water systems used by the Finnish paper and pulp industries
Results of environmental study In plant A, in February 2006, 2.0 × 107 cfu/l of L. pneumophila serogroup 13 was isolated from the active sludge basin, and 1.0 × 104 cfu/l of L. pneumophila serogroup 3 from water circulating around the plant (Table 1)
Summary
Finnish and Swedish waste water systems used by the forest industry were found to be exceptionally heavily contaminated with legionellae in 2005.Case presentation: We report two cases of severe pneumonia in employees working at two separate mills in Finland in 2006. Case A had been exposed to legionellae while installing a pump into a post-clarification basin at the waste water treatment plant of mill A Both the water and sludge in the basin contained high concentrations of Legionella pneumophila serogroup 1, in addition to serogroups 3 and 13. The cooling tower was the only site at the waste water treatment plant yielding that serogroup, though water in the active sludge basin yielded abundant growth of Legionella pneumophila serogroup 5 and Legionella rubrilucens The microscopic PNA-FISH method [8] revealed Legionella pneumophila (L. pneumophila) cells to be present in all waste water basins (up to 1.7 × 1010 cells/l) After these environmental findings, two cases of LD were diagnosed via the occupational health services of the participating paper and pulp mills.
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