It’s the season for cold and flu viruses, and this year, walking pneumonia may be more of a concern as cases rise in Canada and the U.S. and in particular in young people.

The U.S. Centers for Disease Control and Prevention (CDC) have reported a rise in infections since last spring. While Canada does not keep record of cases of walking pneumonia, CBC News reports that anecdotally, cases are on the rise here, too.

Walking pneumonia at its broadest is a lung infection caused by either a virus or bacteria. Dr. Matthew Tenenbaum, the associate medical officer of health for Wellington-Dufferin-Guelph Public Health, said it’s normally fairly mild.

“You might have a cough, fever, sore throat for some time before you begin having trouble breathing,” Tenenbaum said. “If you’re having trouble breathing, it is worth going to see your family doctor or going to [the emergency room] if it’s bad.”

Tenenbaum notes that one of the most notable causes of walking pneumonia — the bacteria mycoplasma pneumoniae — is currently one of the biggest indicators of a growing trend in patients.

Tenenbaum says the public health unit doesn’t track cases, but officials have heard from family doctors and offices that they’re seeing more people with the infection.

“We’ve heard from our colleagues at Public Health Ontario that we have seen since the late summer an increase in the number of tests that came back positive for this particular bacteria,” Tenenbaum said.

“It can’t give us a full picture, but it does corroborate what we’re hearing from physicians about there being more cases.”

WATCH | Children’s doctors warn of spike in highly infectious walking pneumonia:

Dr. Earl Rubin, a pediatric infectious disease specialist at the Montreal Children’s Hospital, told CBC News he’s seeing patients being admitted to hospital for infections.

“Speaking to colleagues across the country in pediatric infectious diseases, everybody is experiencing the same,” Rubin said.

Halifax hospital IWK Health and the B.C. Children’s Hospital in Vancouver have also recorded an increase in children with walking pneumonia since August.

The impact 

Tenenbaum said that it isn’t typical for there to be walking pneumonia cases in children and teens more than adults, but that does seem to be the trend this year.

He said the m. pneumoniae bacteria is gaining unusual traction among young kids, especially those under five, but it’s unclear why this year may be particularly bad for walking pneumonia.

“We know that this particular bacteria that we see increasing in the lab data does have a bit of a cyclical nature, ” said Tenenbaum.

“But again, what’s different this time is the fact that it’s more prone to causing infections for young people, and we don’t really have an explanation for that.”

Rubin told CBC News that there’s no evidence that the bacteria itself has changed, rather the theory is that more and more people are not immune and therefore more susceptible to such an infectious disease.

With a wide range of viruses circulating right now, Tenenbaum said the best course of action if people are feeling unwell is to “stay home, toss the mask on, go see your doctor or nurse practitioner.”

“And of course, if you haven’t yet gotten your COVID shot or your flu shot, please do go out and get those now.”