And we are even starting to report cases in mammals, including marine mammals: nearly a hundred seals in the São Lourenço River have been infected.
Recently, this highly pathogenic H5N1 avian flu has indeed crossed the species boundary: in Canada, there are now red foxes (about twenty), striped skunks (5), and a mink.
The United States also counts coyotes, skunks, raccoons and bobcats among mammals with avian flu. “So far there have been no mammal-to-mammal infections, only bird-to-mammal – probably because the mammal ate the sick bird. This presents a reassuring “dead end” for the disease,” continues Manon Racicot. There are mutations known to have the potential to adapt to mammals or humans. Currently, she explains, pathogenicity studies are being carried out with animal models, such as ferrets, to determine this potential for transmission between mammals.
Add to that, in Quebec, seals. “NOAA (U.S. Ocean Agency) has also confirmed cases in Maine. We are gathering the information and awaiting confirmations,” notes Karina Laberge of Canada’s Regional Fisheries and Ocean Communications Division.
The first for marine mammals in Canada
In the United States, avian flu in seals has already been documented – 168 New England seals died from the H3N8 influenza virus in 2012 – and earlier this summer the virus was detected in four seals in Casco Bay, Maine. This could explain the high mortality observed this year: 92 seals died between May 10 and July 4, without the reason being explained.
“Seals were already known to be susceptible to several influenza viruses, so it’s not surprising,” notes Virologist at the Veterinary Viral Infectious Diseases Laboratory, Carl A. Gagnon.
The Quebec Marine Mammal Emergency Network reported an unusually high number of dead or sick seals in the St. Lawrence in recent weeks. There were reports of 72 seal carcasses caught in June. “We have four times more than usual. More than a whole year. Adults and juveniles”, confirms Robert Michaud.
These would be the first detections of the H5N1 virus in marine mammals in Canada. Of the animals tested – 16 seals – two-thirds are positive for avian flu. The impact these mortalities will have on the seal population remains to be determined.
“This is not of concern for the large seal population, which numbers over 10,000 individuals, but the red flag is raised because of the greater transmissibility of this disease,” notes Robert Michaud, who is also scientific director of the Research and Education Group. in Marine Mammals. It appears, according to Environment Canada, that seals are more likely to develop the disease than gray seals or harp seals, which are also found in Canadian waters.
The proliferation of diseased animals and variants also increases the risk of the disease spreading further in fauna, crossing the borders of other species. If the threat does not weigh heavily on humans yet, summer remains a key period for this new pandemic.
2 million birds raised
After being reported in the United States last year, the disease was first reported in Canada in December in Newfoundland, after wreaking havoc across Europe and Asia in hundreds of poultry farms. It appeared in Quebec in April among wild birds: a goose and two snow geese.
Since then, in poultry, more than 2 million cases have been infected in Canada, mainly flocks of domestic birds. Quebec ranks third with nearly 300,000 domestic birds killed, behind Alberta (22 sites and 937,000 birds) and Ontario (21 sites and 560,500 birds). Since the outbreak of the disease in the spring, Canada has had 108 infected farms, including 11 in Quebec.
“Commercial livestock such as breeding turkeys are particularly susceptible to the disease. It’s a spectacular mortality, with 80% of the cattle dying overnight,” says Manon Racicot. It will therefore be necessary to revise upwards the figure of 300,000.
In Quebec, the disease appeared in the spring among Lac-Brome ducks and infected three or four locations, as well as small farms, in Estrie, Montérégie and the Lower Laurentians. Despite the summer heat, which normally plagues the flu, it continued to spread.
Globally, the virus appears to follow the migratory routes of wild birds. It had been observed before in 2015 in Canada, and it appears that the current version is particularly virulent. And it has many variations. “There are currently four variants, in addition to the original lineage, within domestic flocks and seven variants among wild birds,” explains Ms. Racicot.
Type “A” avian influenza viruses, including H5N1, are transmitted through the air (airborne particles) and also through contact with feces.
Although the disease affects all bird species, domestic birds are particularly vulnerable. Mallards are the main reservoir of the disease. Since 2005, it has been jointly monitored in Quebec by the Canadian Wildlife Service, the Ministry of Forests, Wildlife and Parks and MAPAQ.
It has recently been extended to three turkey farms in Saint-Gabriel de Valcartier. A fourth farm is under investigation. The Valcartier region “is currently our priority. We thought we would have a relatively quiet summer, but now we have birds carrying the disease everywhere,” explains Director General of the Quebec Poultry Disease Control Team (EQCMA), Martin Pelletier.
Egg drop, diarrhea, hemorrhage and sudden death: symptoms vary by species. Asymptomatic cases are also common in ducks.
A worrying summer for wild birds
Dead wild birds have also been reported in Mauricie, the Quebec region, in Gaspésie and as far as the Îles-de-la-Madeleine. However, it is impossible to know precisely how many hundreds of thousands of wild birds were infected and died.
“Reports are done by humans, so it’s just an indicator. There are many wild birds that die alone in the wild. What remains worrying is the spread across the country and the diversity of affected birds,” recalls Martin Pelletier.
In the United States, about 165 mortality events were detected between January 1 and June 13, 2002, in 30 American states: mainly terns, cormorants, pelicans and herons.
“It remains possible that other events will continue to be detected sporadically in the coming months. It is too early to know what the impact will be on colonies of gannets or other species of seabirds in Quebec”, observes publicist for the Ministry of Forests, Wildlife and Parks, Daniel Labonté.
Environment Canada also maintains a database of all reported incidents. “The latter is constantly evolving,” says Matthieu Beaumont, a biologist and emergency response coordinator at the ministry.
One thing is for sure, the list of affected species in Quebec is long: birds of prey (eagles, owls, hawks), scavengers (vultures, crows), waterfowl (geese, ducks, herring and gulls, boobies, common geese, eiders common) and a wild turkey.
At greatest risk of infection, waterfowl and shorebirds such as ducks, geese, gulls and gulls are generally recognized as natural reservoirs of the virus. “Predator or scavenger birds, which feed on waterfowl or their carcasses, are also at greater risk of becoming infected”, confirms Daniel Labonté.
Northern gannets and common eiders, but also great black-backed gulls and herring gulls, are the most affected wild cohorts so far. Thus, more than 5,000 carcasses were collected recently in the Magdalen Islands, mainly gannets.
Their colony on Bonaventura Island also had its share of deaths with nearly 450 carcasses counted. “It is in a small part of the site – the tourist part – which has 200 nests out of a total of 15,000. We will probably have to make a rule of three and wait for the identification rings to come back – our birds are all banded – to find out the real number,” notes UQAR biologist and marine ornithology expert Magella Guillemette.
On the other hand, this year, the hatching of the nests is going well, with more than 70% success. “We will be in a better position in the autumn to govern, but it is not the slaughter we think”, wants to reassure Professor Guillemette.
Loss of 1,000 female Common Eiders
There are also more than 900 carcasses of common eiders, which died on the islands near Rivière-du-Loup between late May and mid-June, reports Jean-François Giroux, a retired professor at UQAM and administrator of Société Duvetnor, which avian influenza monitored in eider ducks.
Of this number, 93% are females – males leave the nests in early June. There are also “360 herring and seagulls, as well as cormorants. It is very different from one island to another and the worst is over, because we have very few new carcasses”, reports M Giroux.
It reminds you of the pasteurella (a bacterium) epidemic, or bird cholera, that wiped out thousands of common Eiders in 2002. “20% of the females succumbed. The colony has been rebuilt and there are between 25,000 and 30,000 pairs.”
In Ile-aux-Lièvres, located between Saint-Siméon and Rivière-du-Loup, some seal carcasses were also found.
The hypothesis is that the seals were infected through contact with sick Common Eiders, with which they share a habitat. “They are reefs and there is a great proximity between the species”. Not in the areas where people visit the island, says Giroux. But this is yet another episode in the spread of the disease.