It was last autumn that dead seagulls and gannets began to wash up on the coast in Galicia, victims of the H5N1 avian flu pandemic that has already killed millions of birds, in captivity and in the wild, all over the world.
Then, in October, something unprecedented was observed. On a farm a few kilometers away, thousands of martens began to die, infected with the same ‘avian virus’.
Scientists believe the conditions on the farm, where tens of thousands of animals are kept in confined spaces, allowed the virus to mutate and be able to spread among mammals, a phenomenon that was also reported in the UK this week.
In this case, foxes and otters became infected after having fed on the carcasses of the birds.
In just over a month, more than 4% of all martens on the Spanish farm died from the haemorrhagic pneumonia that the virus causes. Workers were medicated and quarantined, and the remaining more than 50,000 animals on the farm were all slaughtered by the authorities.
What happened in La Coruña is what experts call a “transshipment event” of the virus, from one species to another, and they warn that it is an event of this type that will be at the origin of the next global human pandemic.
“Laboratory and field evidence has demonstrated that martens are susceptible and permissive to avian and human influenza A (flu) viruses, and may serve as a potential vehicle for mixed interspecies transmission between birds, mammals, and humans,” warns a study. published in Eurosurveillance.
Although the mutated form of H5N1 that spread among martens does not seem to have ‘jumped’ easily to humans, several specialists and scientists point out that fur production farms with these and other animals may prove to be incubators or reservoirs of the viruses, as happened with Covid-19 and other animal-borne diseases.
“It didn’t happen this time, and it may not even happen, but it is one of the scenarios that will give rise to a new pandemic. We are playing with fire”, warns Marion Koopmans, virologist and department director at Erasmus Medical Center Rotterdam, in statements to The Telegraph.
Also Jeremy Farrar, the new chief scientist of the World Health Organization (WHO) points out that the greatest risk of a new pandemic is in animals that link viral transmission between birds and humans.
“Now it appears to be transmitted between mammals, and this is something we don’t want to see. It means that there is an opportunity for the virus to gain mutations that make it more transmissible to humans”, explains the official.
A total of 864 cases of H5N1 infections in humans have been reported since 2003, according to the WHO, with 556 deaths recorded, which gives it a fatality rate of 50%. Most cases occur in workers who work in close contact with birds.
Opinions are divided and, if in Spain, for example, producer associations say that the detected case is proof that the test is working, doctors consider that the risks are too great. “The public health risk is so high that it outweighs any benefit of having farms of this kind”, considers Elisa Pérez a virologist at the Spanish National Institute for Animal Health Research.
The risks are greater if we think that other species, such as cats, mice, rats or bats, could come into contact with the martens on the said farms.
“Wild birds can access the facility, and we’ve already seen an acquired mutation that allows the virus to pass from mammal to mammal. To have fur coats, that’s a risk we don’t want to take,” says Matthew Baylis, director of epidemiology at the University of Liverpool.
Tags: Bird flu spreads among small mammals experts fear humans
