![[ Visit Client Website ]](images/banner.jpg)
BACKGROUND: In September 2014, Alabama Department of Public Health (ADPH) learned of a potential outbreak of Legionella at a copper smelting plant while conducting a routine legionellosis investigation. Multiple employees at the plant had reportedly been out of work sick with respiratory symptoms and diagnoses of pneumonia. The plant opened in May 2014 and is the first US factory for the Chinese-owned company. The plant is located in a rural county and is reported to employ 300 people.
METHODS: ADPH developed a standardized investigation form to obtain information on demographics, clinical history, work location, co-morbidities, and potential environmental sources (other than the plant) for those identified as ill. A confirmed case was defined as an employee with symptoms of legionellosis, or clinical/radiographic pneumonia, with confirmatory laboratory evidence of Legionella infection with onset at least two days after employment start date at the plant. Five sputum samples were obtained from ill or formerly ill employees and tested by the BCL. Environmental testing included collecting water samples and swabs from areas throughout the plant that could have supported the growth of Legionella.
RESULTS: Of the 35 ill employees interviewed, 6 were laboratory confirmed and met the outbreak case definition. Illness onset dates for confirmed cases ranged from August 23 to September 25. The epidemic curve indicates an outbreak with a continuous source exposure. At the site visit, ADPH staff noted a mist from the cooling towers showered on them when they stepped out the facility doors. Legionella pneumophila (Lp) serogroup 1 was isolated from one sputum sample submitted to the BCL. Due to the large volume of growth and sediment in the water samples, it took hours to filter the water prior to testing. Laboratory testing from two environmental swabs taken from the main cooling tower and furnace cooling tower isolated Lp. Although Lp serogroup 1 was identified in the clinical and environmental isolates, CDC determined that the clinical isolate did not biochemically match the environmental samples.
CONCLUSIONS: The epidemiological investigation implicated this copper smelting plant as the source of legionellosis and respiratory illness among the employees. Several individuals were not able to provide sputum for testing or had already been treated with antibiotics. Considering the overgrowth in some of the plates, isolation of all organisms present was not possible. The company was provided recommendation for remediation and elimination of the legionellae. Legionella fact sheets were provided to the employees in English and Mandarin Chinese.