Avian flu, a problem that keeps Europe on alert: "The virus has been behind the great flu pandemics in history"

It can mutate easily (pathogenic), it is highly virulent, it could be transmitted from animals to humans (zoonotic) and now Europe and Africa have become two of its epicenters, where new strains are being created. Avian influenza (H5N1), which was identified in China in 1996, has caused, until 2022 and according to data from the World Health Organization (WHO), the death or slaughter of 131 million domestic poultry.. But it has not been the only species affected. Until now and according to data from the Ministry of Health, there have been 868 isolated infections in humans worldwide.. Some marine mammals, cats, ferrets or minks have also suffered from this type of influenza, one of the most important for public health due to its pandemic potential.

A study published on the 18th by the journal Nature, in which centers from China, Egypt, France, Australia, the United Arab Emirates and the United States participated, confirms that wild birds and their migrations have played a fundamental role in the expansion of the bird flu virus beyond Asia and that, in this global expansion, the disease has undergone mutations giving rise to new types born in these territories.

“Since 2020, there have been genetic changes in the virus, which has caused it to spread much more, reaching other continents,” says Aitor Nogales, virologist at the Animal Health Research Center (CISA, INIA-CSIC).. “The virus has been mutating and one of these subtypes has had more advantage because it has been transmitted quickly and in many places,” adds the expert and recalls that the disease “has had something to do with the last four flu pandemics in history.”. “It is one of the most segmented viruses.”. This means that it joins with other flus to form, for example, the well-known swine flu or also the Spanish flu, which killed more than 40 million people worldwide between 1918 and 1920.

The scientific community is concerned that “bird flu seeks an adaptation that allows it to be transmitted between mammals”

In this sense, Julio Álvarez, researcher at VISAVET, veterinary faculty of the Complutense University of Madrid, points out that, given the establishment of the pathology in Europe, since it previously appeared seasonally, the scientific community is concerned that “the “bird flu looks for an adaptation that allows it to be transmitted between mammals” and, therefore, reaches humans. “In the last four years, a considerable number of cases have been described in this type of animal, something relatively unusual,” says Álvarez.

Specifically, the last outbreak occurred this past July in Poland, when dozens of cats died from the virus.. “It is an issue to monitor because the more cases we have in mammals, the more likely it is that the virus will end up adapting and that it will be transmitted more easily.. It would be a very important change,” says Álvarez. The researcher does not rule out transmission in people and supports Nogales' statements: “This flu is what has been behind the great pandemics in history.”

In reference to a global epidemic, the two experts emphasize the great surveillance that exists around the disease, both at a European and global level, but they do not rule out the possibility of a pandemic and ask the same question: “When?”. “There is no need to be excessively alarmed, it is not like the coronavirus. So far, there has not been a sustained appearance of the virus in mammals,” explains Álvarez.

“We know it will probably happen, but we don't know when, where, or how it will be”

“We know it can occur like many other airborne pathogens.. We know that it will probably happen, but we don't know when, where, or how it will be,” says Nogales.. “If it reached humans it would lose virulence, but it would cause many victims,” he acknowledges and emphasizes that “the zoonotic risk is high.”

“It is not known whether avian influenza viruses and other zoonotic influenza viruses currently circulating will give rise to a pandemic in the future,” says the WHO.. “Given the diversity of avian influenza viruses and others that have caused human infections, it is necessary to maintain constant surveillance in both animal and human populations.”

No spread between farms

In any case, according to the latest report from the Health Alert and Emergencies Coordination Center, dependent on the Ministry of Health, “although the cases can be serious, the low capacity to transmit between people means that the risk is considered very low for the general population”. And he adds: “Likewise, the risk continues to be considered low for workers with occupational exposure on farms affected by sick animals.”. “The risk associated with the consumption of poultry meat or eggs is practically non-existent.”

For an avian influenza epidemic to occur in the world, there would have to have been continuous infections in mammals, something that does not even happen among poultry farms thanks to the surveillance programs already mentioned.. “The good thing that is happening is that there has been very little transmission between farms. When there is a case, strict biosafety protocols are applied and it is controlled and avoided, otherwise the sector could be greatly damaged economically,” explains Álvarez.

According to data from the Health Alert and Emergencies Coordination Center, of the 868 infections in people in the world in 21 countries, 457 have ended in death and “the fatality of the cases of avian flu detected so far amounts to 53%”, although they reiterate that “major outbreaks occur occasionally.”