the essential
A Toulouse researcher, Pierre Bessière, is sounding the alarm: cats, potential intermediaries of the H5N1 virus, could play a key role in a future pandemic. A health threat to monitor closely.
Faced with threats of global epidemics, Pierre Bessière, virologist at the National Veterinary School, monitors infectious agents capable of spreading between species, with a particular focus on felines and their interaction with the H5N1 virus. For more than a year, the specialist has been studying the metabolism of cats and their risk of contamination by avian influenza. Since 2016, this avian strain has spread rapidly, carried by migratory birds, but amplified in high-density farms. The situation among birds is dramatic: “Certain species, such as guinea fowl, display mortality rates of up to 100%,” he observes.
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The scientist collects blood samples from felines taken in veterinary clinics across the country. “These are exclusively felines which have access to the outdoors, which can therefore hunt. Out of a sample of 578 animals, around 1% were infected. I did not expect such a high rate at all. Knowing that there are approximately 15 million cats in the country, a significant portion of which wander outside, this means that there are undoubtedly several tens of thousands of felines who have contracted the disease in France. worrying”, he alerts.
Neurological disorders
and loss of balance
Affected cats may exhibit neurological problems, such as seizures or loss of balance, breathing problems, high fever and general fatigue. These symptoms can be confused with other diseases, and few veterinarians are still aware of this pathology. “The first cases appeared in 2022. It is still very fresh. There is a lot of work to be done with veterinarians to identify the virus and stop its spread,” adds the researcher.
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Among felines, mortality remains low compared to that of birds. On the other hand, the domestic animal is the perfect intermediate host that H5N1 “waits” to infect humanity. “Cats contract the virus by hunting infected birds. We know that when an avian virus infects a mammal, it undergoes mutations to adapt to that host. Cats, like rats for plague, can serve as intermediate hosts where the virus would evolve and eventually become transmissible to humans.” And trigger a pandemic more dangerous than that of Covid-19, closer to that of the Spanish flu between 20 and 50 million deaths between 1918 and 1919.
Biological barriers
The virologist believes that very soon, an influenza virus like H5N1 or similar could cause a global epidemic. Intensive farms act as real incubators. These confined spaces, combining promiscuity and extreme density, offer the pathogen an unprecedented opportunity to evolve and spread. Farms are not only places of propagation: they are also risk multipliers.
However, catastrophism should be avoided: nature has established biological barriers which nevertheless limit the passage of the virus from one species to another, mainly body temperature. “A duck has an internal temperature of 42°C, while a cat is around 38°C. This difference complicates the replication of H5N1. And as transmission to humans will necessarily occur through the respiratory route, the difference in temperature is even more significant in the trachea, in humans, it is at 33°C. In addition, the proteins of the virus must interact with those of the host cell, which requires specific mutations. the virologist. However, its recent work should alert public authorities and further strengthen monitoring of the progress of the virus and the vaccination of birds on French farms.
Avian flu has conquered the globe
Since 2016, scientists have observed increased circulation of the H5N1 virus. Historically, it appeared in Asia, then spread to Europe before spreading to the Americas. Migratory birds have accelerated this spread, while intensive poultry farming has amplified the effects. There is evidence that this disease has spread to cattle, pigs and cats. To limit the spread of this infectious agent, it is crucial to raise awareness among veterinarians and simplify access to reliable tests to identify suspected cases. Cat owners can also help: restrict their animals' access to wildlife or avoid giving them raw meat.
