Legionnaires’ disease cluster linked to a metal product aqueous pre-treatment process, Staffordshire, England, May 2008

Abstract

In May 2008, a report of two workers from the same construction equipment manufacturing plant who were admitted to hospital with Legionnaires’ disease confirmed by urine antigen prompted an outbreak investigation. Both cases were middle aged men, smokers, and with no travel, leisure or other common community exposure to Legionella sources. There were no wet cooling towers at the plant or in the surrounding area. No increase in respiratory disease or worker absenteeism occurred at the plant during the preceding month. Wider case ascertainment including alerts to hospitals and medical practitioners yielded no further cases. The environmental investigation (and sampling of water systems for Legionella) identified a Legionella pneumophila serogroup1 (Mab 2b) count of >3.0x104cfu/l in water samples from an aqueous metal pre-treatment tunnel, which generates profuse water aerosol. Drainage, cleaning and biocide treatment using thiazalone eliminated Legionella from the system.

Confirmed and Potential Sources of Legionella Reviewed

“…Three of the selected publications reported on LD cases linked to cleaning with water in the work environment, but the evidence provided was extremely limited, resulting in low LOEs (III, IV, VI). In a report on a cluster of LD concerning two cases, an aqueous metal pretreatment tunnel in a construction equipment manufacturing plant applied to degrease and rinse steel parts was suggested as a possible infection source …”

“…In a report on a cluster of LD concerning two cases, an aqueous metal pretreatment tunnel in a construction equipment manufacturing plant applied to degrease and rinse steel parts was suggested as a possible infection source. 176 L. pneumophila was isolated from water samples from the aqueous pretreatment system, but no clinical strains were available for comparison. A case-control study was conducted after an outbreak of LD at an automotive plant, and exposure to a cleaning line was associated with LD.…”

The Presence of Legionella in Water Used for Car Washing: Implications for Public Health

“…Indeed, over the years, it has been documented that legionellosis occurs in many types of workers, specifically maintenance technicians of air-conditioning or water supply systems, dentists, workers in oil and gas installations, miners, welders, car washers, workers at biological treatment plants, land workers and workers in the forestry industry [16][17][18][19][20][21][22][23]. Nowadays, it is usually accepted that a predictable risk of exposure to Legionellae could be present in any situation characterized by a work activity using or storing water and where there is the possibility of creating and transmitting water droplets and aerosols that can be inhaled.…”