Experts surprised by rising number of walking pneumonia cases

Experts say a rise in respiratory illness is expected as the temperature drops, but this year, they’re seeing a surprising number of walking pneumonia cases in younger people.

“We see peaks every five years or so. We didn't see a peak last year, but we know other jurisdictions did,” said Dr. Matthew Tenenbaum, the associate medical officer of health for Wellington-Dufferin-Guelph Public Health, in an interview with CTV News. “This may just be part of [the] cyclical nature of how this bacteria circulates. However, we can't explain why it's affecting young kids this time more often. That's still a bit of a mystery to us.”

Common symptoms of walking pneumonia include fever, headache and a slowly worsening cough. Severe symptoms, requiring additional medical care, can range from rashes, to breathing issues, to symptoms impacting the heart and brain.

It is typically is a milder form of pneumonia

“Where someone has an infection that's brewing in their lungs, but it's not necessarily bad enough that they go to their family doctor or primary care provider or go to a hospital,” explained Tenenbaum. “They're dealing with it because it's mild. They don't seek care and they're walking around with it, which means that they can pass on to others.”

Tenenbaum said there are tests to detect the bacteria, mycoplasma pneumoniae, that commonly causes walking pneumonia.

Ontario Public Health last saw the highest number of positive tests in 2019: 5.8 per cent of them came back positive for the bacteria, with a total of 137 positive specimens.

In 2024, 18 per cent of tests were positive, with 733 positive specimens. In Waterloo Region, there were 24 positive tests with 17.6 per cent showing the bacteria, while in Wellington-Dufferin-Guelph, there were six positive specimens, making up 14.3 per cent of overall tests.

“Compared to what we'd expect, we're seeing the biggest increases in the youngest age groups. You know, youth and teens between ages 10 and 20 seem to be about the biggest group, but [it’s] also high for kids under 10. That’s unusual, because that's not usually where we see pneumonia cases cropping up. Usually, it is something that affects people in older age groups,” said Tenenbaum. “The number of tests for this bacteria coming back positive are higher than we would expect. In particular, among those who are younger under age 20 or so. That seems to correspond with reports we're hearing about in the community about more people with these milder forms of pneumonia.”

Tenenbaum said the symptoms of walking pneumonia are similar to influenza and Covid, but can be treated with antibiotics.

Region of Waterloo Public Health encourages residents to stay up-to-date with vaccinations, stay home when sick, consider wearing a well-fitted mask in indoor public settings, and seek medical care for severe, persistent or worsening symptoms.