Avian flu: Why a cold winter is leading to more H5N1 cases among birds

Bird Flu in Toronto: Winter’s Chill Fuels Avian Influenza surge

Toronto’s wildlife is facing a heightened threat from avian influenza (H5N1) this winter.According too officials, the colder-than-average weather has fueled an increase in cases among birds.

A Biting Cold, a virus Resurgence

Heather Reid, head veterinarian at the Toronto Wildlife Center, reported an uptick in avian influenza cases at the beginning of 2025. “In january, after we started having very cold weather, we started seeing increased reporting of suspicious birds that were showing symptoms that seemed consistent with avian influenza,” she explained.

Reid attributes the surge to several factors. First, the virus can survive in cold temperatures. Secondly, as water freezes, birds are forced to gather in limited open areas, increasing their susceptibility to transmission. the stress of the cold may weaken their immune systems,making them more vulnerable.

She notes that this seasonal pattern isn’t new: similar increases in H5N1 cases were observed in Toronto after a cold snap during the winter of 2024.

The Human Risk: Rare but Real

While infection is possible, it’s exceedingly rare for humans to contract bird flu. The virus spreads through contact with animal feces and secretions,including mucus,saliva,and respiratory droplets. Transmission to humans can occur through inhalation, or if these substances come into contact with a person’s eyes, nose, or mouth.

It is crucial to understand that there is no evidence to suggest that eating properly cooked poultry or eggs can transmit H5N1 to humans.

canada’s First Human Case: A Cause for Concern

Last year, a 13-year-old in British Columbia became Canada’s first confirmed case of human avian flu. The teenager spent two months in hospital, requiring intensive care. “The teen spent about two months in hospital, some of it on life support in an ICU,”

Fortunately, there is no evidence of sustained person-to-person spread. However,this occurrence has prompted proactive measures by the Canadian government.

Government Intervention: A Preemptive Strike

On Wednesday, the Public Health Agency of Canada announced that it has secured an initial supply of 500,000 doses of a vaccine against the circulating H5N1 strain. This initiative is a precautionary measure aimed at protecting individuals most at risk from exposure to infected animals.

spring Predictions: Uncertainty and Vigilance

As Toronto anticipates warmer weather, the trajectory of avian influenza remains uncertain. Reid explains that avian flu, like human influenza, is seasonal and exhibits variations in severity across different strains.

While the return of migratory birds in the spring could lead to renewed outbreaks, reid anticipates a decline in cases by June, as high temperatures typically hinder the virus’s survival.

Beyond Birds: Expanding Threats and Protective Measures

The risk posed by avian influenza extends beyond birds. Other animals that scavenge on infected bird carcasses, such as dogs and cats, can contract the virus. In 2023, a dog in Oshawa tragically lost its life after consuming a dead goose likely infected with avian flu pathogens.

“The risk of infection is a good reason to keep dogs on leash and cats indoors, Reid said.

Staying Informed and Safe

The current situation underscores the importance of staying informed about avian influenza, adopting preventative measures, and reporting any suspected cases to local authorities. By understanding the risks and taking proactive steps, we can collectively work to minimize the impact of this evolving threat.

– What specific steps can Torontonians take to protect themselves and their pets from avian flu?

Bird Flu in Toronto: Winter’s Chill Fuels Avian Influenza Surge

Toronto’s wildlife is facing a heightened threat from avian flu

this winter, as officials report an increase in cases among birds due to the colder-than-average weather.

We sat down wiht Dr. Alexander koen,Director of Surveillance and Disease Prevention at the Ontario Ministry of Natural Resources and Forestry (MNRF),to discuss this winter’s avian influenza surge and its implications for both wildlife and human health.

Dr. koen, Toronto has seen an uptick in avian flu cases this winter. What’s driving this increase?

Dr. koen: The cold weather is indeed a major factor.the avian flu virus can survive in низimate temperatures, and as water freezes, birds are forced to congregate in limited open areas, making it easier for the virus to spread. Additionally,the stress of the cold can weaken birds’ immune systems,making them more vulnerable to infection.

Are there any other contributing factors?

Dr. koen: Yes, the return of migratory birds in the fall also plays a critically important role. These birds can carry the virus from one region to another, introducing it to local bird populations.

The human risk of avian flu is considered low. Though, how concerned should Torontonians be?

Dr. koen: While the risk is low, we must remain vigilant. There’s no evidence suggesting that properly cooked poultry or eggs can transmit the virus to humans. Transmission typically occurs through contact with infected animals or their feces and secretions. If you see any suspicious birds, report them to local authorities promptly.

Last year, Canada reported its first human case of avian flu. How has this affected the government’s response?

Dr. koen: Indeed, that occurrence has prompted proactive measures. the federal government recently secured an initial supply of 500,000 doses of a vaccine against the circulating H5N1 strain to protect high-risk individuals. They’re also investing in research and surveillance efforts to better understand and monitor the virus.

What can we expect as we approach spring? Will the avian flu threat subside?

Dr. koen: Avian flu, like human flu, is seasonal. Warmer temperatures typically hinder the virus’s survival, and we anticipate a decline in cases by June. Though, the trajectory remains uncertain, and we could see renewed outbreaks with the return of migratory birds. It’s crucial to stay informed and continue adopting preventive measures.

are there any specific steps Torontonians can take to protect themselves and their pets?

Dr. koen: absolutely. Avoid contact with wild birds and their feces, keep pets on leashes and indoor cats, and report any sick or dead birds to local authorities. By working together and staying informed, we can minimize the impact of this evolving threat.

 

With this interview, we hope to have provided valuable insights into Toronto’s recent avian flu surge and its implications.Stay informed and follow preventative measures to ensure the safety of both our city’s wildlife and its inhabitants.