A lung infection that lurks in drinking water has killed dozens of Americans and sent hundreds to the ER, a new official report warns.
From 2015 to 2020, the bacteria Legionella caused 184 disease outbreaks in the US, resulting in 786 illnesses, 544 hospitalizations and 86 deaths.
The CDC looked at other disease causing pathogens and resulting outbreaks as well, including norovirus and the bacteria Shigella, bring the total number of water-linked disease outbreaks to 214.
The new CDC report said most outbreaks and illnesses – 79 percent and 52 percent – could be traced back to public water systems that supply tab water to homes, office buildings, and hospitals.
Outbreaks caused by legionella specifically spiked after 2015, according to the report’s authors, who urged public health departments across the country to shore up their capacity to detect water-linked disease threats as they arise.
The CDC officials investigated a total of 214 disease outbreaks linked to pathogens lurking in drinking water, including legionella, Shigella, and norovirus
The CDC investigators said: ‘During 2015–2020, Legionella-associated outbreaks continued to increase and were the leading cause of nationally reported drinking water-related outbreaks, hospitalizations, and deaths.
‘This trend was primarily influenced by the increasing number and proportion of Legionella-associated outbreaks linked with community and noncommunity water systems.’
Legionella bacteria spreads when a person inhales aerosols that have been contaminated with it, including from water towers, air conditioning units, hot and cold water systems, humidifiers, and spas.
The microscopic pathogen can cause Legionnaire’s disease, a potentially fatal pneumonia, or Pontiac fever, a less serious illness.
About one in 10 people who do become sick will die. The odds of death are higher when the disease is contracted in a hospital setting, with at least one in four dying.
Last year, 71-year-old Barbara Kruschwitz from Massachusetts died of Legionnaire’s just one week after staying at the Mountain View Grand Resort in Whitefield.
Her husband Henry said she had gone swimming in the pool and at the hot tub at the resort, but he hadn’t.
He said: ‘Her heart had stopped and she couldn’t be revived. And — that’s about as much as I can say.’
Early symptoms of Legionnaire’s include fever, loss of appetite, headache, lethargy, muscle pain, and diarrhea. The severity can range from a mild cough to fatal pneumonia, and treating infection early with antibiotics is key for survival.
Reported outbreaks included 187 biofilm-associated, 24 enteric illness-associated, and three other unknown sources. Biofilms form on surfaces within water systems and serve as an ideal reservoir for bacteria to grow and spread
Legionella can colonize and grow within complex communities of microorganisms called biofilms that form on surfaces within water systems. Once there, the bacteria seeps into the water and becomes aerosolized.
Plumbing systems, especially those associated with warm water, such as hot water tanks and distribution pipes, can also serve as reservoirs for Legionella bacteria to multiply. From there it can contaminate water in pipes. Stagnant or low-flow areas in pipes also foster Legionella growth.
Water treatment plants typically use a disinfectant such as chlorine to clean out the potable water system. In 79 outbreak reports, chlorine was listed as the disinfectant used, while 99 reports did not include the type of disinfectant or treatment used.
In the new report, CDC officials collected reports of 214 outbreaks across 28 states, including those caused by legionella, norovirus, Shigella, Campylobacter, E. coli, and other unspecified pathogens. In total, there were 2,140 illnesses, 563 hospitalizations, and 88 deaths linked to these pathogens.
Of those total outbreaks, 187 concerned pathogens that grew in biofilms and penetrated the water supply. And legionella growing in biofilms caused the greatest number of outbreaks, 184, out of all of them.
Most disease outbreaks were associated with public water systems, which supply most residences and are overseen by city governments.
Seventeen outbreaks were linked to private water systems, such as wells, that some people use to supply their homes. Most of the infections were reported in Illinois, Florida, and Maryland.
The number of Legionella outbreaks fluctuated over the study period, from 14 in 2015 to 31 in 2016, then lower to 30 in 2017, up again to 34 in 2018, down to 33 in 2019, and 18 in 2020.
Researchers did not provide a possible explanation for the peaks and troughs.
However, Covid-era lockdowns, stay-at-home orders, and social distancing measures led to reduced human activity in public spaces such as offices, hotels, and recreational facilities where Legionella is most commonly found, limiting the bacteria’s ability to grow and spread.
Legionella bacteria can multiply significantly in the hot water systems of large buildings like hospitals due to several factors, such as water temperatures below 50 degrees Celsius, areas where water doesn’t flow well and collects, the presence of amoebas and other bacteria, and the materials used in the pipes.
Hospitals, long-term care facilities, and rehab clinics were the most common sources of exposure, accounting for 113 out of the total 214 disease outbreaks.
While the CDC report stops at 2020, local reports of outbreaks from 2023 to 2024 suggest that legionella bacteria could pose a greater threat to public health today than three or four years ago.
For instance, northern Minnesota is contending with an outbreak that has sickened 15 people and sent 11 of them to the hospital since last April. So far, no one has died.
In 2023, the statewide tally was 134 cases related to Legionnaires’ disease, including six deaths.
Also last year in New Jersey, health officials reported that 21 people in Middlesex County and 20 people in Union County became sick and tested positive for legionella. The tests were conducted between Aug. 3 and Oct. 24, when the onset of symptoms occurred.
The state usually records 250 to 375 cases of Legionnaires’ disease annually.
