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

VIDEO: Olympic medalist teaches swimming in Hope

Brent Hayden fondly remembers local swim meet from his youth

VIDEO: LEGO fundraiser builds playground purse

Inspired families built LEGO creations, helped Silver Creek build playground

PHOTOS: 100 years and counting for Boston Bar school

Boston Bar Elementary-Secondary School celebrates Centennial with a bang

Sunshine Valley songbird releases EP

Fifteen-year-old Ashley Pater has been singing and performing since age 9

Rescue boat theft marks third in 3 years for Agassiz-based SAR team

Eight-metre Spirit of Harrison rescue vessel was stolen Friday night, found Saturday morning

REPLAY: B.C. this week in video

In case you missed it, here’s a look at replay-worthy highlights from across the province this week

Suspect who attacked autistic man in Ontario could be from B.C.’s south coast: police

29-year-old man was sent to hospital with serious injuries

Privacy watchdog to explore Facebook leak

Canadian expert says his analytics company helped Trump campaign capitalize on private Facebook info

Woman struck and killed by self-driving Uber vehicle

Ride-hailing company suspends all road-testing of such vehicles in U.S. and Canada

Spring snow melt uncovers dirty needles in B.C. city

Vernon residents are upset with number of needles being found around town with spring melt

US would host majority of games at 2026 World Cup

A decision on the winning bid will be made June 13 at the FIFA Congress in Mexico

‘A perfect storm’: Gas prices could hit $1.60 by April, expert says

Prices will shoot up to 155.7 cents a litre by end of week or early next week

Most people in B.C. too ‘lazy,’ ‘apathetic’ to prepare for disasters: poll

Less than half of those surveyed aren’t insured for earthquakes and wildfires

Chris Hemsworth goes surfing in Tofino

The Australian actor donned a full body wetsuit to catch some waves on Vancouver Island this weekend

Most Read