Protecting families from contaminated food and water
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Protecting families from contaminated food and water
Posted in Legionnaire's disease,Our Blog on September 29, 2025
CDC surveillance data shows Legionnaires’ disease trending upward. The most recent report has an interesting breakdown of where people are getting sick, both geographically and logistically. The report compares data through a five-year span from 2014 through 2018.
Where are people getting sick? What’s causing it. How bad are the illnesses?
How is Legionnaires’ disease trending over time?
Reported cases of Legionnaires’ disease have been consistently trending upward since the early 2000s. Peaking in 2018 with even more cases.
The exception happened during the first year of the COVID-19 pandemic. Likely due to travel restrictions to hotels and limited exposure opportunities during lockdown.
The number of cases rebounded by 2021, when another round of Legionnaires’ disease began trending upward again.
But first, what exactly is Legionnaires’ disease?
Legionnaires’ disease is a pneumonia-like illness caused by inhaling Legionella bacteria.
These microscopic germs typically live in natural water environments like lakes, streams, and rivers. They become a problem to human health when they find their way into our water systems.
According to the Center for Disease Control and Prevention (CDC), 1 in 20 people exposed to Legionella bacteria will become sick.
This type of illness is spread when we breathe in aerosolized water droplets containing those bacteria. Man-made water fixtures are the most common way this happens.
These include:
Legionnaires’ disease can be difficult to diagnose. This is because it presents similar symptoms to other types of pneumonia infections.
In fact, chest x-rays often cannot distinguish between pneumonia and Legionnaires’ disease. A serious problem when specialized treatment is required for this illness for faster recovery.
Specific laboratory tests are required for an accurate diagnosis.
Symptoms to look out for include:
Other symptoms may include:
Most people begin feeling sick between two and 14 days after exposure. However, it can take longer for symptoms to appear in some cases.
Legionnaires’ disease is not a common illness. Somewhere around 18,000 people are hospitalized with Legionnaires’ disease in the United States each year.
Most occurring between June and October.
Warmer months.
This data is counted through certain surveillance systems. You see, Legionnaires’ disease, despite not being a communicable illness, commonly persists in outbreaks. Often, several people become sick with the same illness from the same place.
The CDC gets this data from two sources. Individual cases reporting though the national Notifiable Diseases Surveillance System. As well as the National Outbreak Reporting System. A participant in the Waterborne Disease Outbreak Surveillance System.
In addition to the number of cases of Legionnaires’ disease trending upward, the recent CDC report also shows that the illness is trending among certain groups.
Groups with higher incident rates include:
Additionally, more cases occur in the summer and fall months.
Legionnaires’ disease is not limited to any specific geographical region. Any place in the world can spread Legionnaires’ disease if bacteria have an opportunity to grow and there is an aerosolization opportunity for it to spread.
However, the recent CDC report explains where confirmed cases have been reported most over the years.
In 2016, it was California. Followed by Ohio, New York (state), Pennsylvania, and Florida.
In 2017, the most cases were reported in Ohio. Followed by New York (state), California, and Pennsylvania. Florida and New York City tied for fifth place.
For 2018, Ohio had the most cases. Followed by New York (state), New York City, Pennsylvania, and Michigan.
In 2019, Ohio ranked highest again. Followed by Illinois, New York (state), Pennsylvania, and Michigan.
While the high rise buildings of New York City and New York state often get the most press, I was surprised to see that Ohio stayed at the top of the list throughout the report period.
The most publicized cases of Legionnaires’ disease often involve travel exposure. Often a hotel, cruise, or some other public accommodation. While 66% of the cases reported during this time period could not narrow down the way the disease was acquired (noted as “none of these”), three main places came up in the report.
Healthcare exposure, travel exposure, and assisted or senior living exposure. Among travel acquired illnesses, public accommodations ranked the highest, followed by private accommodations.
In 2014, of the 3,263 cases reported, the highest number or reported cases involved healthcare exposure. In fact, 20% of Legionnaires’ disease cases during the reporting period were acquired this way. This year travel exposure accounted for 14% of Legionnaires’ disease cases, and 4% came from assisted or senior living exposure.
There were 4,001 confirmed cases in 2015. Of the attributable causes, healthcare exposure accounted for 19%, travel exposure accounted for 14%, and assisted or senior living exposure accounted for 3%. The remaining 67% were “none of these.”
In 2016, the number of confirmed Legionnaires’ disease cases rose to 4,150. Again, the order remained the same. Healthcare exposure accounted for 20%, travel exposure accounted for 15%, and assisted or senior living exposure accounted for 4%. The remaining 65% were “none of these.”
Another increase in Legionnaires’ disease occurred in 2017. This year, there were 5,898 confirmed cases. Of which, 21% were attributed to healthcare exposure, 16% to travel exposure, and 4% to assisted or senior living exposure. The remaining 63% were listed as “none of these.”
In 2018, the number of confirmed Legionnaires’ disease cases shot up to 8,764. Though the distribution remained consistent. Healthcare exposure accounted for 18% of those cases. Followed by 15% from travel exposure, and 4% to assisted or senior living exposure. The remaining 67% were listed as “none of these.”
The number of confirmed cases dipped in 2019 to 6,955. Shy of the 2018 number of reported cases, but above that statistic in 2017. Despite the number of travel exposure cases showed a slight increase to 17% and the number of healthcare exposure cases dipped to 18%, the same relative trend persisted. Assisted or senior living facility exposure came up the rear with 3%. The remaining 66% were still “none of these exposures.”
Legionnaires’ disease cases are very serious. In fact, the rate of hospitalizations for Legionnaires’ disease treatment ranges from 91% in 2016 to 96% in 2019. Hospitalizations peaked in 2017, with around 97% of cases requiring hospitalization for treatment.
If you become sick with pneumonia-like symptoms following travel, being in the hospital, or think you may be sick with Legionnaires’ disease, see your healthcare provider right away.
Legionnaires’ disease can be deadly if not treated appropriately. Explain your recent exposure risk and your provider will perform laboratory tests to check for this deadly microbe.
If you are diagnosed with Legionnaires’ disease, your local health department will likely be in contact with you soon. If you are sick with this illness, likely others are too (or soon will be). These investigators will likely ask you about where you have worked, visited, or stayed in the previous weeks to help track down the source. Go ahead and make this list as soon as you are well enough to do so. While this information is fresh in your mind.
If you have recently become sick with Legionnaires’ disease, it is a good idea to get advice from an experienced Legionnaires’ disease Lawyer.
A knowledgeable Legionnaires’ disease lawyer can help you by:
If you wish to pursue a legal claim for financial compensation to cover medical expenses, lost work, caring for a loved one, or other burdens associated with Legionnaires’ disease illness, The Lange Law Firm, PLLC can help. Call (833) 330-3663 or send us an email for a free, no obligation consultation. A member of our compassionate team will go over the details of your case.
Call today to get the help and justice you deserve!
By: Heather Van Tassell (contributing writer, non-lawyer)