Avian influenza, more specifically avian influenza of subtypes H5 and H7, is a disease that must be reported in Quebec since it is a zoonosis, meaning that it can be transmitted between animals and humans.
Human cases of bird flu are very rare, but last spring, three human cases associated with infected dairy farms were reported in the United States. Two infected people had eye symptoms and the third person had a respiratory infection.
Globally, 15 human cases of a specific clade of H5N1 have been reported since the emergence of this clade in 2022: two cases in China, two cases in Spain, five cases in the United Kingdom, four cases in the United States, one case in Ecuador and one case in Chile.
The majority of the cases (11 out of 15) had a history of exposure to poultry, the Quebec Health Ministry said. “Given the small number of human cases reported to date worldwide, the virus appears to have limited capacity to infect humans,” the Health Ministry wrote in an email to The Canadian Press.
“We know that several humans have demonstrated clinical signs. (…) The good news is that it is not transmitted between human beings. The day that it happens is the day that we will get bored of COVID,” commented Dr. Jean-Pierre Vaillancourt, full professor at the Faculty of Veterinary Medicine at the University of Montreal.
“H5N1, in Canada, we have had it for many years, but it is weakly pathogenic. What is generally increasing globally are highly pathogenic viruses. (…) To make a simple definition of highly pathogenic, it is that for four infected birds, there are at least three which die,” summarized Mr. Vaillancourt.
According to him, it is unlikely that things will get complicated in humans, but the risk is not zero. “In general the risk is very minimal while here the risk is low to very low. But low to very low, being a politician or consultant to a politician, I would say: you had better not neglect this, especially in the post-COVID period,” he warns.
The zoonotic epidemiologist explained that bird flu is a virus that replicates and sometimes its mutation allows it to become “a super virus.”
To date, no cases of transmission of the disease to humans have been observed in Quebec or in Canada.
Strengthen protective measures
We have a pandemic in wild birds of a series of H5N1 variants that are highly pathogenic, said Dr. Vaillancourt. “Currently, the series of H5N1 variants that concern us – we have them in Quebec and Canada – we have identified them in at least 489 species of birds and in more than 200 species of mammals,” he said.
In the United States, the virus has been detected in wild birds in every state, in dairy cows in 12 states, and in more than 200 mammals of more than 20 species across the country.
No infected dairy cows have been detected in Quebec and Canada, nor in dairy products.
Following the detection of highly pathogenic avian influenza H5N1 in cattle and goats in the United States, the Public Health Agency of Canada (PHAC) conducted a risk assessment in April. It estimates that for the general Canadian population, the likelihood of human infection with H5N1 acquired from livestock over the next three months remains “very low.”
The situation remains worrying. The Ministry of Health has also mandated the National Institute of Public Health of Quebec (INSPQ) to develop recommendations for protection measures for workers in the sheep, beef and pork industries in the event of an outbreak.
“Indeed, it is a concern that it has entered the ruminant sector such as dairy cattle, kids and alpacas,” said Martin Pelletier, agronomist and coordinator of the Quebec Poultry Disease Control Team (EQCMA).
“This means that the virus is taking hold and this represents additional exposure for the poultry sector, which is more affected by this disease than other types of animals.”
Dr. Vaillancourt shares his concern. “With cows, there are more and more mammals, more and more opportunities for the virus to replicate. On the front lines, it’s a concern for people in direct contact with these animals,” he explains.
The Quebec Ministry of Agriculture, Fisheries and Food (MAPAQ) and its industry partners have invited dairy cattle breeders to increase their vigilance and biosecurity measures.
The Canadian Food Inspection Agency (CFIA) has also enhanced its protection and surveillance measures, including requiring that lactating dairy cows imported from the United States to Canada test negative for highly pathogenic avian influenza.
Worried producers
In 2022, 23 poultry production sites were affected by avian flu in Quebec and this rose to 28 last year. Since the start of the year, three poultry farms have declared the presence of H5N1, according to the Ministry of Health.
“The potential source of contamination is wild birds which are carriers, and they can spread it mainly through their droppings or secretions,” explains Mr. Pelletier. The crux of the matter is therefore to create a barrier between the exterior of the buildings and the interior.
Benoît Fontaine, general director of the Quebec Poultry Disease Control Team, is also concerned about the situation among our southern neighbors.
He said producers are concerned and have made sanitation improvements, such as destroying ponds that attract birds or having separate tractors for fields, set up away from buildings.
He talks about improvements that go beyond the norms, like having a separation bench at the entrance to the chicken coop or washing hands. “I think everyone has increased their biosecurity and that’s maybe one of the reasons why cases are down (this year),” says Fontaine.
The protocol for a site contaminated with avian influenza requires producers to exterminate all their birds and disinfect the building.
If there were cases in cattle, the CFIA would not intervene as it does in the poultry sector, Pelletier said. There would be no depopulation of herds. “It doesn’t have the same impact. For cattle, it manifests itself through certain clinical signs, but there is no mortality,” he explained.
“This is why in Quebec, MAPAQ, with the industry, is developing an action plan for a voluntary self-quarantine and control intervention to minimize the risks of dissemination of the disease,” continues Mr. Pelletier.
In addition to a self-quarantine period for the entry and exit of animals, milk from sick or positive animals would be discarded, MAPAQ said. As an additional precaution, milk from healthy animals in the herd will be sent to a plant that exclusively pasteurizes milk, which destroys the virus.
