By: Stacy M. Brown, NNPA

A recent investigation by the Centers for Disease Control and Prevention and the South Carolina Department of Health and Environmental Control has linked an outbreak of Legionnaires’ disease to a manufacturing facility’s water jet cutters and floor scrubbers. The outbreak, which occurred between August and November 2022, resulted in 34 cases of legionellosis, 15 hospitalizations, and two deaths.

The investigation found that Legionella pneumophila sequence type 36, a particularly virulent strain, was isolated from two water jet cutters and a floor scrubber used at the facility. These machines, which aerosolize water, were identified as the likely sources of infection after multiple employees across different shifts reported symptoms of Legionnaires’ disease and Pontiac fever.

The outbreak came to light in September 2022 when three employees tested positive for Legionella through urinary antigen tests. Following these reports, the health department issued a statewide advisory and worked with facility management to notify employees and encourage testing.

Health officials identified 10 confirmed cases of Legionnaires’ disease, 20 probable cases, and four probable cases of Pontiac fever. The affected employees ranged in age from 18 to 65, with a median age of 40 years younger than the typical demographic for Legionnaires’ disease. Men accounted for nearly 68 percent of the cases.

The outbreak predominantly affected employees working on the third shift, with the highest attack rate at 3.8 percent. Prolonged and overnight exposure may have contributed to the higher rate, investigators surmised.

A comprehensive environmental investigation involved testing 316 water samples from various sources within the facility. Legionella bacteria were detected in samples from two water jet cutters, which operated with water temperatures ideal for bacterial growth, and one-floor scrubber used to clean water overspray from the jet cutters. The machines’ ability to aerosolize water made them effective vectors for spreading Legionella bacteria throughout the facility.

Upon confirmation of the contamination, facility management took immediate action. Both water jet cutters and all floor scrubbers were taken out of service on September 18, 2022. Water jet cutters were decontaminated using mechanical maintenance and biocide treatments and resumed operation on November 16, 2022. Although recommendations for safe use were provided, management opted to replace the contaminated scrubbers with backup equipment. Post-remediation testing confirmed the elimination of Legionella from the machines.

This outbreak underscores the growing risk of Legionella in industrial settings where water-aerosolizing devices are used. The CDC recommends that manufacturing facilities implement and regularly update water management programs to mitigate these risks.

Urbanization, climate change, and aging infrastructure are contributing to the rise in Legionnaires’ disease cases. In the U.S., cases have increased significantly among those over 34 years old.

“Our investigation highlights the need for public health authorities to consider nontypical sources of Legionella exposure in industrial environments,” the report states.