The report’s findings are based upon exposure data from 20 states and New York City. According to the CDC, the analysis was limited to these 21 jurisdictions because they reported exposure details for most of their cases, which allowed the CDC to determine how Legionnaires’ disease was associated with health care facilities.

About 3% of Legionnaires’ disease cases were determined to be “definitely associated with a health care facility,” with 17% of cases listed as “possibly associated with a health care facility.”

“Determining Legionnaire’s disease causation is not simple since the mere presence of Legionella in a water system or device is not sufficient to cause disease. The bacteria must ultimately be inhaled or aspirated into the lungs of a susceptible person to cause disease,” says Michael Patton, member of ASHRAE Committee SSPC 188. “Since people with conditions that have reduced their ability to fight off infections are especially susceptible, it is not a surprise the report found patients in health care facilities to be at risk. It’s vitally important all buildings incorporate good design, operations, and maintenance procedures that prevent growth and spread of Legionella as these are regarded as the best methods of preventing disease.”

ASHRAE officials said the incorporation of a water management plan will reduce the chance of heavy colonization, amplification, and dissemination to people. With this in mind, ASHRAE developed Standard 188: Legionellosis: Risk Management for Building Water Systems to assist designers and building operators in developing a water management plan that includes practices specific to the systems that exist in a particular building, campus, or health care facility.

The standard can be previewed at no cost at https://www.ashrae.org/Standard188.