Today marks 50 years since approximately 4000 legionnaires arrived at the Bellevue-Stratford Hotel in Philadelphia to kick off the 58th annual convention of the American Legion’s Pennsylvania Chapter, not knowing that many of them would contract a deadly illness while there.
The outbreak of what became known as “Legionnaires’ disease” struck 221 persons, 72 of whom did not attend the convention but were in or near the Bellevue-Stratford Hotel over the same period. 34 died (Fraser 1976).
Then started one of the largest epidemic investigations up to that point in history. After about six months, the Centers for Disease Control and Prevention (CDC) investigators traced the illness, which had been named “Legionnaires’ disease” by the press, to a previously unknown bacterium now called Legionella.
Legionella had secretly been causing disease for a long time, probably since the invention of enclosed plumbing systems. The first known hospital outbreak occurred in 1965 when 81 patients at St. Elizabeths Hospital in Washington, DC developed pneumonia and 14 died. The cause could not be found at the time, but 12 years later, after Legionella was discovered, frozen specimens that had been retained from the outbreak were removed from storage and retested. The results confirmed that Legionella was the cause (Brundrett 1978, Goetz 1991, Thacker 1978).
After the 1977 discovery, tremendous amounts of research ensued to find out why water systems promote growth of Legionella and how the bacteria are transmitted to people’s lungs.
By the 1990s, well over 100 scientific papers had been released, as well as publications (OSHA 1996; Freije 1996) that condensed scientific findings into action steps building operators could implement to reduce risk.
ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Guideline 12 was first published in 2000. Significantly, the CDC, which up to then had recommended a largely reactive approach to Legionnaires’ disease, wrote that, “Adoption of the ASHRAE guidelines could dramatically reduce the likelihood that legionellae will be amplified in a water system, thereby diminishing the risk of transmission” (Fields 2002).
Among the most important Legionella guidelines and standards in the United States, ASHRAE Standard 188 is definitely king. The June 2015 release ASHRAE 188 was a giant step for Legionella prevention in the United States in part because it represented unprecedented agreement among government agencies and industry groups—not only about the need for Legionella prevention in building water systems—but also about the approach to it.
In recent years, new standards have significantly increased requirements related to water management programs. For example, ASHRAE 514, which became an ANSI standard in July, 2023, significantly broadened the scope and increased the level of detail for water management programs. The stated purpose of ASHRAE 188 is to reduce one illness (legionellosis) by managing only one hazard (Legionella) in building water systems. By contrast, the stated purpose of ASHRAE 514 is to “reduce illness and injury from physical, chemical, and microbial hazards,” expanding the scope from one microbe to an unspecified number of microbes as well as to physical hazards (scalding) and chemical hazards.
Future of Legionnaires’ Disease
Although more research is needed to know how better to prevent Legionnaires’ disease, evidence indicates that the reason Legionnaires’ cases have been on the rise since ASHRAE 188 was released is not due to lack of knowledge, but lack of action.
Our 2021 study of more than 900 water management programs clearly showed that the premise of ASHRAE 188 is sound – fully implementing a comprehensive water management program will reduce Legionella in water systems. The problem is that very few facilities are doing so. The CDC found that 70% of the deficiencies implicated in Legionnnaires’ outbreaks from 2015 to 2109 were in WMP implementation.
Most hospitals are required to implement water management programs (WMPs) either by law or by their accrediting organization, but very few non-healthcare facilities that should be implementing WMPs based on ASHRAE 188 even have one. State health departments realize this, and some are working on adopting regulations. States indeed hold the keys to preventing Legionella infections.
New Jersey’s regulations, effective later this year, require Legionella water management programs for all building types and water systems per ASHRAE 188. Since 2015, other states have established regulations but only for specific types of water systems (cooling towers) or only for healthcare facilities.
All eyes are on New Jersey and other states, to see if they succeed. Whether cases of Legionnaires’ disease in the US continue to rise or are drastically reduced depends on states establishing smart regulations – and inspecting WMPs well.