(Montreal) The rise in cases of avian flu on farms in the United States, the contamination of herds of cows and cases recently transmitted to humans worry Quebec and Canadian authorities who say they are monitoring the situation very closely.
Avian influenza, more precisely avian influenza subtypes H5 and H7, is a disease subject to mandatory reporting in Quebec since it is a zoonosis, that is to say 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 cases (11 out of 15) had a history of exposure to poultry, the Quebec Ministry of Health said. “Given the small number of human cases reported to date globally, the virus appears to have a limited capacity to infect humans,” the Ministry of Health wrote in an email to The Canadian Press.
“We know that several humans have shown clinical signs. […] The good news is that it is not transmitted between humans. The day it happens is the day we get bored of COVID,” commented Dr Jean-Pierre Vaillancourt, full professor at the Faculty of Veterinary Medicine at the University of Montreal.
“In Canada, we have had H5N1 for many years, but it is weakly pathogenic. What is generally increasing at the global level are highly pathogenic viruses. […] “To give a simple definition of highly pathogenic, it is that for every four infected birds, at least three die,” Mr. Vaillancourt summarized.
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 better not neglect this, especially in the post-COVID period,” he warns.
The specialist in the epidemiology of zoonoses explained that avian 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 yet been observed in Quebec or Canada.
Enhance 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 from more than 20 species across the country.
PHOTO AMANDA PEROBELLI, REUTERS ARCHIVES
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. She estimates that for the Canadian population as a whole, the probability of human infection by H5N1 acquired by livestock over the next three months remains “still 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 farmers 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.
Producers worried
In 2022, 23 poultry production sites were affected by avian flu in Quebec, compared to 28 last year. Since the beginning of the year, three poultry farms have reported the presence of H5N1, according to the Ministry of Health.
“The source of potential contamination is wild birds that 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 buildings and the interior.
Benoît Fontaine, general director of the Quebec Poultry Disease Control Team, is also worried about the situation in 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 norm, like having a dividing bench at the entrance to the hen house or washing hands. “I believe that everyone has increased their biosecurity and that is perhaps one of the reasons why cases are down (this year),” said Mr. 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, said Mr. Pelletier. There would be no herd depopulation. “It doesn’t have the same impact. For cattle it manifests itself by certain clinical signs, but there is no mortality,” he explains.
“This is why in Quebec, the MAPAQ, with the industry, is developing an action plan for a voluntary self-quarantine and control intervention to minimize the risks of spreading 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 thrown away, MAPAQ said. As an added precaution, milk from healthy animals in the herd will be sent to a plant that exclusively pasteurizes milk, which destroys the virus.
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