Duck farms under pressure

Jean-Christophe Dardenne is a duck farmer in Isle-Jourdain in the Gers. Normally, its animals are raised in the open air. But because of the bird flu epidemic, his poultry have been confined for a few months. A complicated decision to assume for Jean-Christophe, who does not have the necessary infrastructure indoors.

"It's something difficult for them and for us to live with," he said. "Some lots will never see the light of day and the sun." According to him, confined animals will develop less quickly and less well, leading to a loss of overall meat and foie gras production. The farmer lives under the constant threat that the disease will be detected on his farm, which would force the veterinary services to slaughter all his animals. For now, this scenario has been avoided on his farm, which is not directly affected by the virus. "It seems to me a total aberration this type of management, it really poses a lot of worries for the future," worries the breeder, for whom vaccination is the solution to get out of this impasse.

The most devastating wave in history

This highly pathogenic virus, codenamed H5N1, is not new. First identified in a Chinese goose farm in 1996, influenza or avian influenza is transmitted between birds through droppings and respiratory secretions.

The wave affecting Europe is the fourth since 2015. On an unprecedented scale, it is the most devastating in the history of the continent. A total of 47.7 million poultry were euthanized on the continent in 2022, including 16 million in France alone. The country is particularly impacted.

The virus, which normally occurs in winter, behaves in unusual ways. This time, it continued to spread throughout the year, including in summer defying the seasons. Scientists are concerned about this. The virus infects a wider spectrum of birds and many other species such as mammals.

A Covid-19 scenario?

The big question today is the risk of transmission to humans. It is currently weak, but not non-existent. The more the virus spreads, the more it will evolve. Scientists are therefore closely monitoring the mutations of the virus to better prepare the response.

It is at the national reference laboratory on avian influenza in Ploufragan, Brittany, that samples taken from farms across the country arrive. Scientists analyze them for the presence of the H5N1 strain. Béatrice Grasland, virologist, confirms the virulence of this wave: "It's unprecedented, it's three times more [outbreaks, editor's note] than previous epizootics."

For now, the virus is avian, that is, only contagious in birds. But researchers are monitoring transmission in other animal species, including mammals. In 2022, a domestic cat was contaminated. "The risk of having viruses that can adapt to humans and cause potential future pandemics increases," warns Beatrice. Unlike Covid-19, the bird flu vaccine already exists. "We potentially have a virus that has never been encountered by humans," continues the researcher. "So we would have an unprecedented epidemic that we would have to deal with quickly."

Wild birds: vectors and new victims

The epidemic is hitting wild birds with new intensity. Usually, the latter carry and transmit the disease during migrations, without being particularly decimated. But today, the trend is quite different: wild birds are dying by the thousands. "Here in France, we found that there were two large groups of birds that were affected," says Cédric Marteau, director of the nature protection division, at the League for the Protection of Birds (LPO). "First the raptors (...) Worldwide, we had never seen a vulture contaminated by avian influenza. And then the seabirds."

Sad example: the Northern Gannet, a species of seabird that lives in Brittany. In total, 40% of the adults died, and 90% of the chicks. A hecatomb that worries about the future. "We will have a lot of trouble getting the population to recover," anticipates Cédric Marteau. The main concern is that the virus is attaching itself to a species already in danger of extinction.

500 kilometers away, in the Paris region, dead seagulls float on Lake Viry-Châtillon, in Essonne. The services of the Grand-Orly Seine Bièvre collected no less than 1,400 birds in three weeks in February. Seagulls, but also gulls, ducks, swans and moorhens. Sébastien Viprey, biodiversity manager of the Grand-Orly Seine Bièvre lakes unit, fishes dead birds with his landing net. They will then be stored in a large refrigerator and then sent to rendering. "We didn't think we were going to get to this rate," admits Sébastien, humbly. "This is unheard of." He advises walkers never to touch or pick up these dead animals which, unfortunately, lie at the water's edge.

Mass vaccination in fall 2023

According to official veterinary services, it is impossible today to control the infection without going through the box of mass vaccination. The French government has set itself the goal of launching the first poultry vaccination in autumn 2023. Jean-Luc Guérin leads the tests at the National Veterinary School of Toulouse. Tests with two vaccine solutions are conducted on partner farms. Animals are closely monitored for antibodies.

In parallel, molecular tests are carried out to verify that the virus does not circulate in vaccinated herds. "We know that in France, palmipeds, including ducks, play a major role in the dynamics of infection," explains Jean-Luc Guérin. "Which means that if you can control the infection in ducks, you gain a lot of the disease control."

The main challenge is to ensure that vaccinated animals are not healthy carriers of the virus and therefore potentially transmitters. Hence an international mistrust of vaccinated animals. But today, the scale of the epidemic somewhat erases this reluctance, which becomes almost secondary, after the urgency to stem the spread in farms.

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