TORONTO — As we enter 2025, Dr. Theresa Tam has her eye on H5N1 bird flu, an emerging virus that had 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 this country more than two decades ago, but is making an accelerated resurgence.

But on the same day as The Canadian Press interview with Tam, health officials announced the first case of severe [human] illness in the U.S. — a person over 65 in Louisiana who had been in contact with sick birds in a backyard flock.

Tam said there have been close to 170 measles cases in Canada in 2024, compared to 59 cases last year. Many cases are related to a large outbreak that started in the fall in New Brunswick and has since spread through travel to people in Ontario, she said. The majority of people affected had not been vaccinated.

Measles was declared eliminated in Canada in 1998. Cases since then can generally be traced back to someone who travelled and brought in the virus from another country — then it spreads to those who aren't immunized.

Tam said one of the factors likely driving the resurgence of measles and whooping cough is the disruption to children's routine immunizations during the COVID-19 pandemic. Despite "catch-up" programs, "we're still not back at the pre-pandemic levels of vaccine coverage.”