Between April 1 and September 30, 2022, 209 dead or sick seals were reported in the estuary and Gulf of St. Lawrence. The increase in summer deaths among harbor and gray seals was nearly four times greater than historical data. For several specimens, the H5N1 strain of avian flu was identified as the cause of death.
Results of an investigation published in the Centers for Disease Control and Prevention (CDC) suggest that the presence of large numbers of H5N1-infected bird carcasses at seal landing sites most likely contributed to the spread of pinniped infection.
Current data cannot determine whether transmission between seals may have occurred. “In the epidemic that we experienced in 2022 particularly among harbor seals, there appears to be no evidence that the virus was transmitted from one seal to another. What we can think is that the disease was so acute, the death so rapid, that the animals did not have time to excrete the virus for very long,” explained the co-author of the ‘investigation. , Stéphane Lair.
That said, the current H5N1 strain has caused “very significant” deaths among pinnipeds, including sea lions in South America. “We are talking about several thousand animals that have died, which suggests that in these cases, there was transmission from one sea lion to another. And in these herds of sea lions, they have much closer contact with each other, which could have favored this kind of direct transmission between the sea lions,” said Mr. Lair.
His work highlights that marine mammals could serve as reservoirs for the H5N1 avian influenza virus, which could contribute to increasing the risk of mutations favoring the infection of new mammalian hosts. Therefore, surveillance of this virus in wild marine mammal populations is essential to assess the public health risk associated with this emerging pathogen-host dynamic, the CDC report states.
More recently in Quebec, the Canadian Food Inspection Agency conducted two investigations related to avian flu in domestic birds. The infection was detected on November 17 and 18 on two poultry breeding sites in Montérégie.
Don’t panic, according to two experts
A first human case of H5N1 avian flu in Canada was confirmed last week in British Columbia.
According to two experts, we should not panic at the idea of the virus being transmitted between humans since cases are few. “Cases have already been reported in humans. These cases are quite limited in number, which suggests that this virus is poorly adapted to humans,” assures Mr. Lair, who is also a professor at the Faculty of Veterinary Medicine of the University. from Montreal.
“What we need to understand with influenza viruses is that they make recombinations between viruses, mutations. And so, they can evolve over time. The one currently circulating in North America is a Eurasian strain, different from the Asian strain which has caused several human cases. This strain seems much less likely to be transmitted between humans than the Asian strain,” he explains.
What is more worrying, according to Mr. Lair, is that this virus can mutate and we do not know what adaptation future generations of the virus will have.
“Public health is always a little more concerned when this avian virus begins to infect mammals like seals because this demonstrates that there is a certain adaptation to mammalian cells and since we are mammals, we can ask the question : are we next on the list? », he asks.
Brian Ward, a full professor in the department of medicine at McGill University and co-director of the MUHC’s Center for Vaccine Studies, also has moderate concerns. “It’s worrying, but it’s worrying at a low level,” he said.
“In recent years, there have been cases in elephant seals, farm animals and domestic birds. But in wild birds, notably seabirds, geese and ducks, these viruses have been circulating very actively for decades. We now have histories of multiple clades and yes, there are mutations that facilitate transmission to mammals,” he describes.
So far, there have been no cases of human-to-human transmission. “There is no clear sign that this is going to change quickly,” comments Mr. Ward.
“Transmission in birds is mainly by the fecal-oral route, so the stools contain the virus. There are birds around the seals. Aerosols form in these environments. It is possible that even without a suitable receptor in the event of infection, the seal could become ill from the intensity of the aerosols,” Mr Ward said.
MM. Lair and Ward agree that the next pandemic could be avian flu. However, they believe there is no cause for excessive concern. “Don’t panic yet, but we need to take advantage of this moment, while these viruses have our attention. We need to use this motivation to be better prepared when one of these viruses appears or another virus like SARS-CoV-2. We must prepare for future pandemics because they are inevitable,” says Ward.
**Given the successful mitigation efforts against previous pandemics, what are the most critical lessons learned that can be applied to monitoring and controlling the spread of H5N1 in marine mammals and preventing its evolution into a human pandemic?**
## World-Today-News Exclusive Interview: Avian Flu in Marine Mammals – Cause for Concern?
**Introduction:**
Welcome to World-Today-News. Today, we delve into a growing concern: the spread of avian influenza, specifically the H5N1 strain, among marine mammals. We are joined by two distinguished experts, Dr. Stéphane Lair, a professor at the Faculty of Veterinary Medicine of the University of Montreal and co-author of a recent study on the topic, and Professor Brian Ward, a full professor in the Department of Medicine at McGill University and co-director of the MUHC’s Center for Vaccine Studies.
**Section 1: The Spread of H5N1 in Marine Mammals:**
* **Dr. Lair,** your study suggests a link between H5N1 infected bird carcasses and seal deaths in the Gulf of St. Lawrence. Can you elaborate on the findings and the potential pathways of transmission from birds to seals?
* **Professor Ward,** how prevalent is H5N1 in wild bird populations, and how does this relate to the emergence of the virus in marine mammals like seals?
**Section 2: Human Risk and the Potential for Mutation:**
* **Dr. Lair,** cases of human infection with H5N1 are rare, but they do occur. What factors make this virus a potential threat to human health, and what can we learn from the genetic makeup of different H5N1 strains?
* **Professor Ward,** you mentioned that there is no clear indication of human-to-human transmission of H5N1. However, given the virus’s ability to mutate, is there a possibility of it becoming more transmissible among humans in the future?
**Section 3: Lessons Learned and Preparing for Future Pandemics:**
* **Dr. Lair,** given the potential for future pandemics, what steps can be taken to monitor and prevent the spread of H5N1 and other zoonotic diseases?
* **Professor Ward,** what are the key takeaways from this situation regarding pandemic preparedness? How can we leverage this current awareness to be better prepared for future health threats?
* **Both Experts,** should the public be concerned about H5N1? What practical steps can individuals take to protect themselves and their communities?
**Conclusion:**
Thank you, Dr. Lair and Professor Ward, for sharing your valuable insights. This discussion highlights the interconnectedness of animal and human health and the need for ongoing vigilance and collaborative efforts to address emerging infectious disease threats.
We encourage our viewers to stay informed about H5N1 and other zoonotic diseases through reliable sources like the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).
