Legionellosis is a severe bacterial infection, most commonly presenting as pneumonia (Legionnaires' Disease), caused by Legionella bacteria. It is not contagious person-to-person and primarily affects individuals who inhale contaminated water droplets, especially older adults or those with weakened immune systems.
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Legionellosis first gained widespread recognition following a major outbreak in 1976 at an American Legion convention in Philadelphia, Pennsylvania. The causative bacterium, *Legionella pneumophila*, was identified by the CDC shortly after. This event significantly advanced public health understanding of waterborne diseases and the importance of environmental controls in buildings.
Legionellosis is primarily transmitted through the inhalation of small water droplets (aerosols) containing *Legionella* bacteria. These contaminated aerosols are generated from man-made water systems such as cooling towers, hot tubs, showers, decorative fountains, and large plumbing systems. It is not known to spread directly from person to person.
Contagious Period: Varies by disease
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The New York City Health Department has launched a probe into a concerning cluster of Legionnaires' disease cases along the Upper East Side -- with officials trying to track down the source of the outbreak.
Two people have been diagnosed with the potentially fatal pneumonia-like illness in the neighborhoods of Carnegie Hill and Yorkville as of Thursday, with possible additional cases pending test results, according to the health department.
Authorities are asking New Yorkers who have lived, wor
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An ongoing cluster of the illness has sickened 23 people. That's not unusual: Most years, 200 to 700 people in the city are diagnosed with the disease.
Faced with an outbreak of Legionnaires' disease on Manhattan's Upper East Side, the Mamdani administration said on Tuesday that it was adopting new tactics to try to stamp out clusters of the bacterial illness more quickly.
The outbreak has sickened 23 people, leading to 17 hospitalizations. Legionnaires' disease is a form of pneumonia caused by
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An unexpected increase in cases of Legionnaires' disease in parts of north-west and south-west London is being investigated by The UK Health Security Agency (UKHSA).
Specialists are trying to find out if the cases are linked and to establish the possible source of the disease.
Experts are looking at each case of the disease to have broken out this year, interviewing patients or their families to retrace their steps to find out if there is a common link, the UKHSA said.
The disease - a severe f
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This event envelope contains reports on Legionnaires' diseases cases, clusters and outbreaks in the UK.
Source: BEACON - View Full Report
This event envelope contains reports on Legionnaire's disease cases, clusters and outbreaks in Australia.
Source: BEACON - View Full Report
This event envelope contains reports on legionellosis in Canada.
Source: BEACON - View Full Report
Tim Fang is a digital producer at CBS Bay Area. A Bay Area native, Tim has been a part of the CBS Bay Area newsroom for more than two decades and joined the digital staff in 2006.
A hospital in Santa Clara County is working to find the source of contamination that led to several people being infected by Legionella bacteria.
Officials at Kaiser Permanente Santa Clara said Tuesday they have confirmed several cases of people being infected by the bacteria. Legionella occurs naturally in water and
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Hamilton Public Health is investigating several confirmed cases of legionellosis in the city's east end and Stoney Creek area.
In a news release Friday, the city said 13 cases of legionellosis -- a lung infection caused by legionella bacteria -- have been reported since May 4. Public health officials are working to id
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ST. LOUIS COUNTY, Mo. - An elementary school in the Ritenour School District will remain closed after a teacher there disclosed that she had been hospitalized for Legionnaires' disease during the school year.
In separate statements to staff and families in the district and Marvin Elementary School, Superintendent Dr. Chris Kilbride said administrators learned late Tuesday evening that a teacher said she was ill in late April and early May and had been hospitalized for Legionnaires.
The teacher
📰 12 news sources reporting on this story.
This envelope includes reports on legionellosis (clusters and outbreaks) in the United States.
Source: BEACON - View Full Report
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View WHO Resources →Disease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.
Last reviewed: 2026-07-18
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