Remediation of novel sources linked to an outbreak of Legionnaires’ disease in a manufacturing facility

In September 2022, public health officials identified a legionellosis outbreak among workers at a manufacturing facility. Upon recognition of the outbreak, public health officials and company management investigated to identify the source and prevent additional cases. Facility management assembled an inventory of potential water sources and worked with a consultant to conduct sampling. Legionella bacteria were cultured from bulk water samples collected from two water jet cutters and a floor scrubber. All other sampling locations had no Legionella identified by culture. Legionellosis cases were distributed throughout the facility. Floor scrubbers were used to clean up water that spilled from the water jet cutters and to clean the floors adjacent to employee work areas. After multiple cycles of cleaning and disinfection of the water jet cutters and floor scrubbers, repeat sampling revealed no Legionella detected. Company management returned the equipment to service in November 2022 with a maintenance, disinfection, and monitoring plan; no additional cases of legionellosis among employees have been reported. Evidence indicates that water jet cutters provided a conducive environment for Legionella growth, while floor scrubbers may have also contributed to employee exposure. This case study describes a remediation plan and illustrates the importance of identifying all potential Legionella sources and maintaining a comprehensive water management program to protect workers from Legionella and other waterborne pathogens.