A man walks pass a sign for flu shots in Toronto. (Doug Ives/The Canadian Press)

Flu cases spike across Canada, signaling peak of epidemic: experts

The dominant influenza A strain is H3N2, which tends to infect seniors in greater numbers

The number of flu cases is continuing to rise across Canada, suggesting the peak of infections with one of the dominant circulating strains could come within a few weeks — or even sooner, say infectious diseases experts, who describe this influenza season as “unusual.”

“We really haven’t seen a season quite like this in a little while,” said Dr. Michelle Murti of Public Health Ontario, referring to the mix of two primary strains making people sick during this year’s epidemic.

The dominant influenza A strain is H3N2, a nasty virus that tends to infect the elderly in greater numbers, with concurrent circulation of a B strain, a type that typically causes less severe illness. Influenza B can also affect older people and is the strain that most often infects children.

READ MORE: Researchers claim the ‘man flu’ does exist

READ MORE: B.C. rolls out 2017 flu shots

“Normally in a season, we’ll see a peak of influenza A happening some time towards the end of December or through January,” Murti said Monday. “And as that is coming down toward the end of February, that’s when we start to see that peak of influenza B activity into the spring and later season.”

But this year’s B strain, known as B/Yamagata, began circulating in the fall, much earlier than is usually the case.

B.C., for example, is seeing an atypical 50-50 mix of H3N2 and B/Yamagata, although other regions in Canada may have different ratios of the two strains affecting their populations, Dr. Danuta Skowronski of the BC Centre for Disease Control said from Vancouver.

“The spike in influenza activity that we’re experiencing now is not unusual,” she said. “In fact, such a sharp increase in activity is a signature feature of influenza that distinguishes it from other respiratory viruses that have a more prolonged, grumbling activity through the winter period.”

Skowronski described graphs illustrating flu activity as looking like a church steeple — with a sudden rise, a peak and then a sharp decline.

“We are currently spiking, but whether we have passed the peak or are continuing to rise, it’s still too early to tell,” she said, adding that peaks may arrive at varying times across the country as regions and communities experience major upticks in cases at different points in the epidemic.

In its weekly FluWatch report, the Public Health Agency of Canada says there were 11,277 laboratory-confirmed cases of flu across the country as of Dec. 30 — about 70 per cent attributed to H3N2 — with more than 1,000 influenza-related hospitalizations and 34 deaths.

However, Murti said those figures are an underestimate of the actual number of cases, as most people don’t seek medical attention for flu and, therefore, aren’t tested. As well, not all provinces and territories keep track of hospitalizations due to influenza.

“Looking at our numbers over the last couple of weeks and knowing there’s a bit of a reporting delay, we’re certainly on the upswing right now in terms of increasing activity for flu,” she said of Ontario. “So probably in the next few weeks, we’re going to continue to see increased activity.”

Murti predicts the province’s peak — for H3N2 cases, at least — will likely come in the next few weeks.

“But you really don’t know the peak until you’re coming down the other side,” she said.

Sheryl Ubelacker, The Canadian Press

Just Posted

B.C.’s north heats up to record highs

Bella Bella, Masset, Prince Rupert and the Cassiar Area all broke records

Ottawa proposes restricted pot labels, packages

Packaging will include red stop sign with marijuana leaf and ‘THC’

How to keep local news visible in your Facebook feed

Facebook has changed the news feed to emphasize personal connections. You might see less news.

B.C. Scientists witness first-ever documented killer whale infanticide

“It’s horrifying and fascinating at the same time.”

Okanagan Falls winery showing international photo project

Liquidity Wines will be sole Canadian show of National Geographic’s Photo Ark

Lawyer for one suspect in beating of man with autism says he’s not guilty

Ronjot Singh Dhami will turn himself in, lawyer said

Liberals awarded $100,000 contract to man at centre of Facebook data controversy

Christopher Wylie says his voter-profiling company collected private information from 50 million Facebook users

Facebook’s Zuckerberg admits mistakes in privacy scandal

Zuckerberg admits to privacy scandal involving a Trump-connected data-mining firm, but no apology

UPDATE: Former B.C. city councillor sentenced nine months for sexual assault

Dave Murray, convicted this past fall, hired a private investigator to intrude on the victim’s life.

Online threat to U.S. high school traced to Canadian teen

A 14-year-old girl has been charged in connection with an online threat against a high school

Most Read