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What an outbreak of avian influenza in humans would look like and how we can deal with it

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.Covid has put us in a pandemic scenario that virologists and epidemiologists warning about for years. One of the candidate viruses to give us a scare was then – and is now – avian influenza. The ability of the virus to reach other species has been demonstrate, although it has not yet made the definitive leap that could really worry us.

“There was a wave between 2004 and 2015 of human detection of avian influenza, which is when surveillance was improving, then there were years of calm since 2016. Now it is resurgent, but we have not reached the levels of bird flu of that time,” says immunologist and virologist Margarita del Val.

What an outbreak of avian influenza in humans would look like and how we can deal with it

Epidemiologist Daniel López Acuña points out that “the appearance of cases of avian influenza A(H5N1). In humans in Cambodia, which has been reported to the WHO. Is worrying because of the potential for massive human-to-human transmission. Which could represent a major pandemic risk”. According to this expert. The increase in cases among wild birds and the risk of transmission to domestic birds have already been seen with concern. Even more worrying has been the presence of H5N1 in mammals, both wild and in breeding centres such. As the mink farm in Galicia that was affected by the infection,” adds the epidemiologist.

“Is it spreading more in mammals?” asks Margarita del Val, “Yes. But mammals were not being monitore as much before. Is it spreading more in South America. Yes, but now it is being monitored more in South America,” she says.

What an outbreak of avian influenza in humans would look like and how we can deal with it

For the scientist, one of the lessons learned from Covid’s experience is that surveillance is now being steppe up. For Margarita del Val. The two current related cases in Cambodia “would not yet imply human-to-human transmission because it is also compatible that they may have been infecte. As there are examples in the recent past. Maybe one is more vulnerable than another.

Both experts, who have been giving us the keys to the Covid pandemic for years. Say that the most important thing is surveillance, because the leap from bird flu to humans would be very worrying given its very high mortality. “It is good that there is this surveillance, because having the information is important. We don’t fully know the dynamics of bird flu transmission to people. There were twelve years during this century in which there was a lot of transmission to people. There was an average of 70 cases per year with 53% mortality between 2004 and 2015,” recalls Del Val.

What if it makes the leap to humans?

Although, as the virologist points out, it is not known how bird flu is transmitted to humans it is known what it needs to multiply successfully. “In people who get the virus as far as the lungs, it can multiply and leave them in shambles. That’s why it has such a high mortality rate. If the virus were to multiply also in the upper respiratory tract, it would infect more people, and perhaps many would be in a mild condition, although we don’t know that. But what is clear is that there would be a lot of human-to-human transmission,” he says.

Birds have a different respiratory system to mammals and the virus would have to make changes at the molecular level in order to multiply in humans in the upper respiratory tract. “We know, at the molecular level, the changes in the virus that would make the jump to humans possible.