Avian flu, the next pandemic?
Public Health Everything you need to know about the largest outbreak of bird flu in Europe that also affects Spain with the first human case
Spanish case "There are no reasons for alarm. The risk for the population remains low
Europe is experiencing an epidemic of bird flu unprecedented both in extent and number of cases.
With almost 50 million poultry slaughtered and more than 3,500 detections in wild birds, the first recorded human infection in the EU was detected a few weeks ago, a worker from a farm in Guadalajara who easily overcame the contagion.
At the beginning of 2022, a case had been detected in the United Kingdom, the first on the continent.
North America is also experiencing an unusual expansion of the virus, with a confirmed human case in the state of Colorado.
We speak with Elisa Pérez Ramírez, a researcher at the Animal Health Research Center (CISA-INIA-CSIC).
What is happening with the bird flu?
It's the million dollar question.
It is still not clear what is favoring this unprecedented expansion of the virus and what is causing so much illness and death in wild birds, which was something that did not happen before.
More studies are needed to know if it is due to characteristics of the virus or is more related to ecology, to environmental conditions.
The expansion is being global.
As in Europe, in North America there are also very important outbreaks.
One of the hypotheses suggests that temperatures and humidity have affected migratory changes in birds.
It is also suggested that this year's drought has caused the birds to have had to group together in small wetlands, which favors transmission.
But the characteristics of the virus genome also need to be thoroughly studied.
We know that it is a highly pathogenic H5N1, but its peculiarities must be well understood.
There have been cases in humans.
Could it cause the next pandemic? Human cases have been very sporadic considering that millions of birds are affected.
Bird-to-human transmission does not occur easily.
Having said that, we must be very vigilant and carry out close surveillance because the virus is giving warnings of its potential.
Several cases have been detected in mammals.
Viruses force us more and more clearly to implement a 'one health' approach in which specialists in the environment, human and animal health work hand in hand.
What does it mean that cases have been detected in mink on a farm in Galicia? It was known that mink and other mustelids, such as ferrets, are susceptible to influenza viruses.
In fact, they are used as an animal model for experimentation in the laboratory to reproduce human disease and carry out studies.
What is worrying about this species is that it could become a flu virus cocktail shaker, as is the case with pigs.
As they are permeable to different types of influenza virus, there is a risk that recombinations may occur in their organism that give rise to new variants with the capacity to infect mammals.
It would be necessary to study how these infections have been produced.
Taking into account what also happened with Covid and these animals, I think the existence of these farms should be reconsidered.
In addition to ethical and biodiversity problems, they pose a significant problem for health security.
How is the threat of bird flu monitored? The Ministry of Agriculture's surveillance program works fairly well and includes both active and passive surveillance of wildlife and poultry.
For example, if an increase in mortality is detected on a farm, it is notified and official veterinarians carry out analyzes that are sent to the Central Veterinary Laboratory of Algete (Madrid).
If the disease is detected, the animals are slaughtered, the farm is disinfected and security perimeters are established.
In addition, workers are tested.
This is how the case of the affected worker in Guadalajara was detected.
Passive surveillance also contemplates analyzing a certain number of animals per farm on a regular basis to ensure that everything is fine.
This surveillance is also carried out on wild birds.
Is there a risk that the virus will become endemic? Yes, clearly that risk exists.
Previously, avian flu seasons were closely associated with the migratory passage of wild birds coming from the North and mainly included autumn and winter.
This year, on the other hand, has been one of the first in which cases have been detected throughout the year.
Quite a few cases have been recorded in summer, something that was previously very rare.
If this strain continues to circulate so successfully there is a high risk that it will become endemic in wild birds.
And that has many implications for the economy, animal health, etc.
In addition to H5N1,
Are there other dangerous combinations?
In general, only H5 and H7 viruses are considered to have the ability to go from low to high pathogenicity.
And among those, the ones that to date have managed to infect and cause disease and death in humans are H5N1 and H7N9.
There have been sporadic cases of other viruses, such as H5N8, which managed to infect workers on a Russian farm, but the major scares have been caused by H5N1 and H7N9.
In any case, we must closely monitor these viruses and their evolution.
The first H5N1 emerged in 1997 in Hong Kong.
It was the first time that it was found to have a pathogenic capacity for wild birds, which until then had acted only as a reservoir for the virus, without getting sick.
The virus circulating now is of that lineage,
but with modifications that could be giving it a greater capacity to infect and cause disease globally.
After what happened this season, has the risk estimate for humans changed? According to the latest ECDC report, the risk to the general population is still considered low.
What has changed is the risk estimate for people who have contact with birds, which has become moderate.
It is estimated that the risk to ranchers, veterinarians, workers who are responsible for slaughtering and disinfecting farms, banders, researchers in the area, etc. is moderate. We are starting the high season again.
What are the forecasts? Yes, we do not know how it will evolve but it does not seem that it will improve from what we have seen so far.
We will have to see a little how migrations are this year and how many birds arrive.
It is important to monitor risk areas, where there are more wetlands.
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