Distracted by the winds of war, the media don't emphasize it (and basically it's a good thing), but we are witnessing the largest bird flu epidemic ever recorded in known history.
Millions of chickens, turkeys, ducks and geese have been culled, and thousands of wild birds have died from the H5N1 virus. Virologists from all over the world are carefully following the evolution of the epidemic: and slowly the sense of danger is increasing. Is it justified?
How dangerous is the H5N1 virus to humans?
H5N1 is an influenza virus that primarily affects birds. So far, fewer than 900 people worldwide have been infected with the virus, and around half of them have died. At present, avian flu is not easily transmitted between humans: most infected people contract the virus directly from chickens, turkeys, ducks or geese. As such, H5N1 has not yet caused a human epidemic or pandemic.
So why are bird flu fears growing?
There are three main reasons why bird flu has grown in media attention.
- The current outbreak of avian flu, caused by the H5N1 2.3.4.4b variant, is truly the largest ever recorded in all time.
- The H5N1 virus is infecting an increasing number of bird and mammal species, increasing its geographic spread and generating new variants.
- H5N1 appears to be transmitted effectively between individuals of at least one mammalian species, mink, as has been observed in Spain in 2022. Many sea lions in Peru have also been affected by bird flu. If the virus can spread among mink and possibly sea lions, it could also among humans.
What could contribute to the spread of H5N1 among humans?
Bird flu primarily affects the intestines of birds and is spread through faeces in water. In contrast, human flu affects the respiratory tract and is spread through breathing and coughing. To effectively infect mammals, avian influenza viruses must mutate in several ways.
One of the most important mutations involves the ability of the virus to infect a specific part of the body. And we know that mutations of this kind are possible.
Avian and human influenza viruses use receptors called sialic acidspresent on the cell surface. Bird flu viruses, such as H5N1, exploit a version called sialic acid α2,3-linked, while human influenza viruses use sialic acid α2,6-linked (the predominant variant in the human upper respiratory tract).
To trigger human infection, H5N1 would have to mutate to use α2,6-linked sialic acid as a receptor. This is the cause for concern, as several studies have shown that one or two mutations in the viral genome may be sufficient for this step.
Can we prevent avian flu, for example develop a preventive remedy?
In a word: no.
With bird flu viruses, it is not possible to create effective human vaccines in advance, because it is not known exactly what the genetic characteristics of the virus will be if it starts spreading among humans. At present, the best way to protect yourself from H5N1 is to avoid contact with infected birds.
And in the meantime, whether you trust it or not, health authorities and many research laboratories are working together to monitor the H5N1 situation and prevent the possibility of a human pandemic.
Because we can (and must) prevent it from becoming another nightmare
Surveillance is currently high, and the containment and disinfection activity of farms and sensitive areas has been even more decisive. Research studies the possible dynamics of mutations and bodies such as the Center for Disease Control study emergency plans and disseminate guidelines to avoid any kind of contagion.
The COVID-19 pandemic has increased global awareness and preparedness for emerging infectious diseases. For this reason we have a duty to act more rationally: citizens can avoid being overwhelmed by panic, institutions can avoid making impulse decisions that could prove to be not only wrong, but counterproductive.
In summary: it is right to keep your attention high (do not touch dead animals and cook poultry well) but this time the key word is "lucidity".
