A lung infection lurking in drinking water has killed dozens of Americans and sent hundreds to the emergency room, a new official report warns.
From 2015 to 2020, the bacterium Legionella caused 184 disease outbreaks in the US, resulting in 786 illnesses, 544 hospitalizations and 86 deaths.
The CDC also looked at other disease-causing pathogens and resulting outbreaks, including norovirus and the bacterium Shigella, bringing the total number of water-related disease outbreaks to 214.
The new CDC report states that most outbreaks and illnesses – 79 percent and 52 percent – have been traced to public water systems that supply drinking water to homes, office buildings and hospitals.
Outbreaks caused by legionella especially increased after 2015, according to the report’s authors, who urged public health departments across the country to strengthen their capacity to detect water-related 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 researchers 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 associated with community and non-community water systems.’
Legionella bacteria spread when someone inhales aerosols contaminated with it, such as from water towers, air conditioning systems, hot and cold water systems, humidifiers and spas.
The microscopic pathogen can cause Legionnaires’ disease, a potentially fatal pneumonia, or Pontiac fever, a less serious illness.
About one in ten people who do become ill will die. The risk of death is greater if the disease is contracted in a hospital setting; at least one in four dies.
Last year, 71-year-old Barbara Kruschwitz from Massachusetts died of Legionnaires’ complications just a week after a stay at the Mountain View Grand Resort in Whitefield.
Her husband Henry said she went swimming in the resort’s pool and hot tub, but he didn’t.
He said: ‘Her heart had stopped and she could not come back to life. And that’s about as much as I can say.”
Early symptoms of Legionnaires’ disease include fever, loss of appetite, headache, lethargy, muscle aches and diarrhea. Severity can range from a mild cough to fatal pneumonia, and early treatment of infections with antibiotics is key to survival.
Reported outbreaks include 187 biofilm-associated, 24 enteric disease-associated and three other unknown sources. Biofilms form on surfaces in 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 in water systems. Once there, the bacteria seep into the water and are atomized.
Plumbing systems, especially those associated with hot water, such as hot water tanks and distribution pipes, can also serve as reservoirs for the multiplication of Legionella bacteria. From there it can contaminate water in pipes. Stagnant or low flow areas in pipes also promote the growth of Legionella.
Water treatment plants typically use a disinfectant such as chlorine to clean the drinking water system. In 79 outbreak reports, chlorine was listed as the disinfectant used, while 99 reports did not specify the type of disinfectant or treatment used.
In the new report, CDC officials collected reports of 214 outbreaks in 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 associated with these pathogens.
Of those total outbreaks, 187 involved pathogens growing in biofilms and entering the water supply. And Legionella growth in biofilms caused the largest number of outbreaks, 184, of all.
Most disease outbreaks were linked to public water systems, which supply water to most homes and are overseen by city governments.
Seventeen outbreaks were linked to private water systems, such as wells, that some people use to supply water to their homes. The most 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 down to 30 in 2017, up again to 34 in 2018, to 33 in 2019 and 18 in 2020.
Researchers offered no possible explanation for the peaks and valleys.
However, Covid-era lockdowns, stay-at-home orders and social distancing measures have led to reduced human activity in public spaces such as offices, hotels and leisure facilities where Legionella is most prevalent, limiting the bacteria’s ability to grow and spread was limited. .
Legionella bacteria can multiply significantly in the hot water systems of large buildings such as hospitals due to several factors, such as water temperatures below 50 degrees Celsius, areas where water does not flow properly and collects, the presence of amoebae and other bacteria, and the materials used are used in the pipes.
Hospitals, long-term care facilities and rehabilitation clinics were the most common sources of exposure, accounting for 113 of the total 214 disease outbreaks.
While the CDC report stops at 2020, local reports of outbreaks between 2023 and 2024 suggest that Legionella bacteria could pose a greater threat to public health today than it did three or four years ago.
Northern Minnesota, for example, is experiencing an outbreak that has sickened 15 people and sent 11 of them to the hospital since April last year. So far no one has died.
In 2023, the statewide count was 134 cases linked 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 ill and tested positive for Legionella. The tests were conducted between August 3 and October 24, when symptoms began.
The state usually records 250 to 375 cases of Legionnaires’ disease each year.