Are people catching Legionnaires Disease from face masks? Fact Check

Online rumours claim that wearing face masks intended to curb COVID-19 can help the wearer contract Legionnaires Disease.

Such rumours are frequently shared through an anecdotal story about someone who allegedly called into a radio talk show to claim his wife had been diagnosed terminally ill with COVID-19 only for it to be later diagnosed with Legionnaires Disease and ultimately successfully treated with a course of antibiotics.

FALSE

An example of the message is below.

Mask wearers beware… ⚠️ sanitize rather than wear it and risk it
A caller to a radio talk show recently shared that his wife was hospitalized and told she had COVID and only a couple of days left to live. A doctor friend suggested she be tested for legionnaires disease because she wore the same mask every day all day long. Turns out it WAS legionnaires disease from the moisture and bacteria in her mask. She was given antibiotics and within two days was better. WHAT IF these “spikes” in COVID are really something else due to improper mask wearing??
Copied and pasted😷😷😷😷😷😷 DO NOT SHARE!!!

Legionnaires Disease is a type of bacterial infection that results in pneumonia, and is caused by the Legionella bacteria, that can be found in natural water supplies such as lakes, ponds and streams, but can also be found in man-made structures such as cooling and plumbing systems. According to the CDC, it is typically transmitted when air droplets originating from infected sources get into the air and are breathed in by people, or is aspirated into the lungs when drinking infected water.

It is unclear from the message above exactly how people would contract Legionnaires Disease by wearing a face mask. Transmission of the bacteria is typically by breathing in droplets of infected water that originate from outside sources. That is a process that – if anything – would be slowed down by wearing a face mask.

The moisture on the inside of a face mask is naturally from the wearer themselves, and as such, if they had not contracted the bacterial disease, there should be none present on the inside of their mask. Additionally, the Legionella bacteria cannot survive on dry surfaces, so it is unlikely to be inhaled from a mask.

One of the leading resources on Legionnaires Disease, Legionella.org, has dismissed the claims –

You cannot contract Legionnaires’ disease from wearing face masks. Legionella bacteria is transmitted by aspirating drinking water or breathing in water droplets. Legionella is not spread from person-to-person in respiratory droplets nor does the bacteria survive on dry surfaces. Your mask would not be a source of transmission for the Legionella bacteria.

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Additionally, Professor Hugh Pennington, emeritus professor of bacteriology at the University of Aberdeen, told Reuters in response to the viral claims –

Legionella bacteria are not carried in the nose/throat, so how would they get onto the mask in the first place? They come from environmental sources and cause problems when warm water sources like industrial cooling towers or jacuzzis or hotel air conditioners … have been poorly maintained, and contaminated water then sprays into the air…
I am not aware of any that say that mask wearing is a risk factor for developing the disease

While there is no evidence that wearing face masks causes Legionnaires Disease, many experts predict a possible surge in the disease as workers return to their offices. And that is because stagnant water in cooling and plumbing systems in large office blocks left alone for months may serve to be breeding grounds for the bacteria, which could subsequently infect workers returning to their workplaces.

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However, in these reports, there is nothing specific to face masks exacerbating the transmission of the bacteria. In fact, the opposite is true. Amy Pruden, PhD, a professor of environmental and water resources engineering at Virginia Tech, said that face masks could possibly slow the transmission of the disease in infected areas.

I don’t know if it has been studied… but it seems logical that wearing a mask in the restroom and elsewhere in the office would reduce the possibility that you would inhale these airborne bacteria and become ill.

As for the man telling his anecdote in a phone-in radio show, we’ve been unable to identify him or the radio show. And even if he does indeed exist, we are still only hearing his interpretation of events. The claim that a person could be given only days to live, only to find out they had a different type of bacterial disease that could be treated with a simple course of antibiotics seems, at the very least, quite suspect.

Either way, the claim has been dismissed by experts and we rank the claim false.