The National Academy of Sciences, Engineering and Medicine looks at the risks of the deadliest U.S. water sickness.
Legionella thrive in warm, stagnant water. Reported cases of Legionnaires’ Disease in the United States more than quadrupled between 2000 and 2015. Photo © J. Carl Ganter / Circle of Blue
By Brett Walton, Circle of Blue
Researchers, government officials and technical experts met in Washington, DC on February 8 for the first meeting of a study by the National Academy of Sciences, Engineering and Medicine to minimize the spread of Legionella bacteria in construction pipes and municipal water systems.
Legionnaires’ disease affected at least 6,141 people in the United States in 2016, killing several hundred, a number higher than any other water-related disease in the country. However, there are more questions than answers about pneumonia, the bacteria that cause it, and the factors that lead to infection.
Known for authoritative scientific reports informing public policy, the academy brought together a group of 13 experts with backgrounds in engineering, microbiology, infectious diseases, water treatment, public health and facility management.
The range of subject areas gives an indication of the complexity of the task.
It’s not typhoid or cholera. These water-borne diseases are extremely rare or are being eliminated in the United States. But the number of legionnaires has more than quadrupled in the past 15 years. The aim of the study is to elucidate a disease that was discovered relatively recently, in 1976. Which of the 60 or so Legionella bacteria strains are the most worrying for human health? Can a disease be diagnosed faster and more accurately? The lung disease is not contagious and is spread by inhaling mist that carries legionella. Several studies suggest that the number of reported cases is well below the number of infections.
In the case of water systems, the Committee will investigate factors that increase the risk of Legionella growth. Inside the building, this means water temperature, water stagnation, pipe design, disinfection and age of the pipes.
Some commentators urged the committee to focus on the contribution of municipal water systems. Road construction, water pipe breaks or changes in water chemistry – as was the case with the Legionnaires’ eruption in Flint in 2014 and 2015 – can catalyze bacterial growth or contaminate the distribution system.
“We fear that the public water supply is not sufficiently focused before it enters the building,” said Daryn Cline, director of science and technology for the Alliance to Prevent Legionnaires’ Disease.
Cline argued that Legionella management guidelines tend to respond to large outbreaks. However, these events account for only 4 percent of Legionnaires’ disease cases, according to the Centers for Disease Control and Prevention. The rest are people or cases where the source of infection has not been identified.
In particular, those responsible for managing buildings or overseeing regulations wanted practical advice from the committee on reducing risk and assessing whether preventive measures are working, said Shantini Gamage of the Veterans Health Administration.
Finding that studies have found Legionella bacteria to be prevalent in plumbing, Gamage wondered what guidelines managers should follow for test locations and frequencies, what concentration of bacteria should be considered, and what reactions a positive test should produce. “Is every building a ticking time bomb?” Asked Gage. “How do we know what to prioritize?”
Gamage also questioned the reliability of laboratory tests, reporting a time when their department sent the same water sample to four laboratories that gave four different results. “Should we act if this is the test result?” She asked.
The study, which is expected to take 18 months to complete, is sponsored by three federal agencies – Centers for Disease Control and Prevention, Environmental Protection Agency, Department of Veterans Affairs – and the Alfred P. Sloan Foundation, a philanthropic group interested in microbes in Cities and buildings.
Brett writes on agriculture, energy, infrastructure, and the politics and economics of water in the United States. He also writes the Federal Water Tap, Circle of Blues weekly round up of US government water news. He is the winner of two reporting awards from the Society of Environmental Journalists, one of the highest honors in American environmental journalism: first place for explanatory coverage for a series on septic tank pollution in the United States (2016) and third place for beat reporting in a small market (2014). In 2018 he received the Sierra Club’s Distinguished Service Award. Brett lives in Seattle, where he hikes in the mountains and bakes cakes. Contact Brett Walton
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