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Bacteria in masks not causing Legionnaires’ disease

August 5, 2020 GMT

CLAIM: People are getting Legionnaires’ disease from bacteria in masks and the cases are being mistaken for coronavirus, driving the spike in cases.

AP’S ASSESSMENT: False. Legionnaires’ disease is a severe form of pneumonia that is caused by inhaling tiny water droplets containing Legionella bacteria. It is not spread person to person, according to the Centers for Disease Control and Prevention.   

THE FACTS: Social media users are sharing a post that falsely suggests that bacteria in masks is resulting in people contracting Legionnaires’ disease, which is being mistaken for COVID-19, and leading to a spike in reported coronavirus cases. The bacteria that causes the Legionnaires’ disease, Legionella, can spread in buildings through air conditioning and water systems. 

Dr. Jonathan Parsons, a pulmonologist at The Ohio State University Wexner Medical Center, said there is no scientific basis for the claim. 

“There is no way that the environment that would be produced from a damp mask is going to be suitable for Legionella to grow in any kind of quality to cause Legionnaires’ disease,” he said. 

Coronavirus cases surged in July in states including Arizona, Texas, California and Florida. Experts blamed the spike on Americans not wearing facial coverings and following social distancing measures to prevent the spread of the virus.

Posts making the false claim were shared thousands of times on Facebook. A comment on one post said that mask wearers were making themselves sick. 

The post implies that because COVID-19 and Legionnaires’ disease have similar symptoms they are being confused. While they do have similar symptoms, they are two completely different diseases. Unlike coronavirus, Legionnaires’ disease can be treated with antibiotics. 

The bacteria that causes Legionnaires’ disease does not live on our bodies or on masks, said Dr. Seth Cohen, who heads the infectious disease clinic at University of Washington Medical Center Northwest. 

“The science clearly shows that masks both prevent the acquisition of COVID and prevent transmission of COVID to other people,” he said.

The post comes after U.S. Rep. Louie Gohmert, a Republican from Texas, tested positive for the coronavirus last week and speculated in a Twitter video how he might have caught the virus. 

“I don’t know about everybody but when I have a mask on, I am moving it to make it comfortable,” he says in the video from July 29. “I can’t help but wonder if that put some germs in the mask.”

Parsons said the odds of getting coronavirus from your mask are negligible. 

As coronavirus cases increase and government officials mandate that masks be worn in public, posts online continue to target masks. The Associated Press has debunked several false mask claims, including that masks decrease oxygen levels and cause pleurisy, an inflammation of the lining around the lung.


This is part of The Associated Press’ ongoing effort to fact-check misinformation that is shared widely online, including work with Facebook to identify and reduce the circulation of false stories on the platform.

Here’s more information on Facebook’s fact-checking program: