Par Nicole Ireland
As 2025 dawns, Dr. Theresa Tam has her eyes set on H5N1 avian flu, an emerging virus that caused its first human case in Canada this year.
At the same time, Canada's chief public health officer is closely monitoring measles, a virus that was eliminated in the country more than two decades ago but is experiencing an accelerated resurgence.
The H5N1 virus, a highly pathogenic strain of avian influenza virus transmitted by wild birds, is on the rise worldwide. It has decimated poultry farms in Canada and infected herds of dairy cows in several states south of the border.
However, its spread to humans is particularly worrying.
“What concerns me particularly is that this virus has demonstrated the ability to cause a range of clinical outcomes, from asymptomatic infection… to rare cases of severe illness,” Ms Tam said, during an end-of-year interview on December 18.
“So it’s something that we really need to be very vigilant about.”
The only Canadian patient with the H5N1 virus, a teenager from British Columbia, was seriously ill and hospitalized in November. Provincial health officials have still not been able to determine how the teen became infected.
No one else has contracted the virus, Tam said, which is encouraging because it suggests there has not yet been human-to-human transmission.
Although the risk to the general public is still considered low, there have been at least 65 confirmed human cases in the United States in 2024, primarily among agricultural workers. Most cases have been mild, with conjunctivitis among the symptoms.
Raise awareness among the general public
But on the same day as Ms. Tam's interview with The Canadian Press, health authorities announced the first case of serious illness in the United States – a person over 65 in Louisiana who had been in contact with sick birds in a backyard breeding operation.
“(This) tells me that we need to do a lot of outreach not only to commercial poultry farms, for example, but also to people who raise chickens or other backyard birds,” Tam said.
“These backyard birds are exposed to wild birds carrying this H5N1 virus.”
It is important to educate everyone who raises birds in Canada, not just commercial farms, to wear personal protective equipment and take biosecurity measures, she argued.
Ms Tam said it is also time to raise awareness about bird flu among the general public.
“We need to handle sick or dead birds (or) other animals with great care,” she argued.
“When in doubt, do not touch and call your local veterinarian or public health authority for advice on what to do if you have dead birds or animals in your garden or yard.”
Increase in cases of measles and whooping cough
But it's not just new illnesses that worry Ms Tam.
“There is an increase in the circulation of a certain number of vaccine-preventable diseases such as measles, such as whooping cough,” she said.
Tam said there will be nearly 170 cases of measles in Canada in 2024, compared to 59 cases last year.
Many of the cases are linked to a large outbreak that began in the fall in New Brunswick and has since spread to people in Ontario through travel, she said.
The majority of those affected had not been vaccinated.
Children can be particularly affected by measles, she said. A child under the age of five died in Ontario this year, something “we haven't seen in a very long time,” Tam said.
“These are truly incredible reminders of why we need to continue to get vaccinated.”
Most parents have never seen measles and may not realize the severity of the disease, because “very effective vaccines” have protected children against measles for decades, Tam said.
Measles was declared eliminated in Canada in 1998. Cases since then can usually be traced to someone traveling and bringing the virus back from another country — and then it spreads to those who aren't vaccinated.
“It is such an infectious virus that it will seek out everyone who is not vaccinated,” Ms Tam said.
“It’s a serious illness. Children get very sick and sometimes have to be hospitalized.”
Whooping cough is also making a comeback after being controlled by vaccination for years, Ms. Tam said.
It can make young children very sick, and health professionals often call it the “100-day cough.”
Tam said one of the factors likely to cause the resurgence of measles and whooping cough is the disruption of routine childhood vaccinations during the COVID-19 pandemic. Despite “catch-up” programs, “we have still not returned to pre-pandemic levels of vaccination coverage.”
COVID-19 to watch out for
Regarding COVID-19 itself, Tam said the virus continues to evolve and spread, but has not established a predictable pattern like seasonal flu or respiratory syncytial virus ( VRS).
The flu is starting to increase and RSV activity is high, but the number of COVID-19 infections has declined since the fall, Tam said.
“We don’t see them coming together into one big ‘triple outbreak’ like we saw two years ago.”
The fact remains that an increase in COVID-19 is possible this winter, and the elderly and those with underlying chronic illnesses are still particularly vulnerable to serious illness, recalled Ms. Tam.
Washing your hands, wearing a mask and staying home when sick, as well as getting up-to-date vaccinations, continue to serve as “layers of protection” against circulating viruses, she said.
— With information from the Associated Press.
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The Canadian Press' health content receives funding through a partnership with the Canadian Medical Association. The Canadian Press is solely responsible for editorial choices.
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