Two Legionnaires' disease cases associated with industrial waste water treatment plants: a case report

<p>Abstract</p> <p>Background</p> <p>Finnish and Swedish waste water systems used by the forest industry were found to be exceptionally heavily contaminated with legionellae in 2005.</p> <p>Case presentation</p> <p>We report two cases of severe pneumonia in employees working at two separate mills in Finland in 2006. <it>Legionella </it>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 <it>Legionella </it>infection, the waste water and home water systems were studied in more detail. The antibody response and <it>Legionella </it>urinary antigen finding of Case A indicated that the infection had been caused by <it>Legionella pneumophila </it>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 <it>Legionella pneumophila </it>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 <it>Legionella pneumophila </it>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 <it>Legionella pneumophila </it>serogroup 5 and <it>Legionella rubrilucens</it>. Both workers recovered from the disease.</p> <p>Conclusion</p> <p>These are the first reported cases of Legionnaires' disease in Finland associated with industrial waste water systems.</p