Legionella Responsible for 98 Percent of Waterborne Deaths
Legionella-associated outbreaks are the leading cause of water-related outbreaks, hospitalizations, and deaths throughout the nation, according to the CDC. Legionella, a type of bacteria that can form hazardous biofilms, is responsible for causing the potentially fatal Legionnaires’ disease, a severe form of pneumonia.The number of Legionella-associated outbreaks in the U.S. fluctuated annually, with 14 outbreaks in 2015, 31 in 2016, 30 in 2017, 34 in 2018, and 33 in 2019, before declining to 18 in 2020. Collectively, these Legionella-associated outbreaks accounted for 37 percent of all waterborne illnesses (876 cases), 97 percent of hospitalizations (544 cases), and 98 percent of deaths (86 cases) during the five-year period, according to the report.
Each year, waterborne pathogens, including Legionella, sicken more than 7 million Americans, with 118,000 of these cases requiring hospitalization and 6,630 resulting in death. The burden of waterborne diseases is over $3 billion in direct health care costs.
One out of every 10 people who contract the disease will die from complications. Alarmingly, the death rate surges to one in four for those who acquire it during a stay in a health care facility.
What Fuels Rapid Legionella Growth?
Although Legionella bacteria are naturally present in fresh water sources without typically causing disease, the bacteria can rapidly multiply and become a health hazard in man-made water systems like plumbing if the water is not adequately treated and maintained.
Legionella thrives in warm water, growing within biofilms—slimy, glue-like substances that can accumulate in water pipes.
Public water systems, for instance, can become sources for Legionella growth, posing potential health risks as people inhale the bacteria present in the air surrounding the contaminated water. Other common sources of Legionella infection include potable water used for showers, cooling towers in air conditioning systems, decorative fountains, and hot tubs.
Where Was Legionella Found?
Legionella outbreaks did not only occur in community water supplies but were also associated with outbreaks in health care settings nationwide. Between 2015 and 2020, they accounted for about two-thirds of all hospitalizations and three-fourths of all deaths related to the bacteria, according to the CDC.Furthermore, Legionella was found in private water supplies, such as hotels, motels, lodges, or inns, and more alarmingly, the CDC notes, in private homes.
Temporary housing faced 111 outbreaks, resulting in 444 cases, 364 hospitalizations, and 73 deaths due to Legionella. Between 2015 and 2019, there were three outbreaks in private residences, causing seven cases and four hospitalizations.
Determining the upstream causes in water supplies that could lead to Legionella would likely be challenging, the CDC noted. Water suppliers and municipalities should closely examine plumbing systems to ensure their safety, the agency added.
