Record number of birds infected with bird flu, what to do with this virus?

• Maartje Geels

  online editor

A young swan bobbing its head uncontrollably and a young wild goose sitting in the grass, tossing wildly from side to side. When you think bird flu, you probably think of chickens being slaughtered on a poultry farm. But wild birds are also infected with the virus on a large scale. And that’s potentially bad news for people, experts say.

It seems that as of October 2021, Europe is grappling with the largest bird flu epidemic ever from recent European data. Around 2,500 outbreaks have been recorded on European poultry farms and the virus has been diagnosed around 3,000 times in wild birds. Equally worrying, according to the European health service ECDC, is that the virus has spread to 37 European countries.

Furthermore, the avian influenza virus has also been detected in mammals. For example, a black bear was found with the bird flu virus in Canada in the summer of 2022, and an infected skunk and fox were found in the Netherlands last year. And those are no exception.

Thijs Kuiken, a virologist at the Erasmus Medical Center, is one of the experts who warn of the dangers of avian flu. He doesn’t, he says, because there has been more attention to virus outbreaks since the corona pandemic. The epidemic we are seeing among poultry and wild birds is simply much larger than previous avian flu epidemics.

But what are we talking about when we talk about the “bird flu epidemic”? Avian flu is a collective name for several variants of influenza viruses in birds. Most of these variants are mild in nature, but they can develop into a severe and nauseating variant. This variant has been circulating in Europe since October 2021.

Wild migratory birds carry the virus with them and thus infect birds “on land”. These can be waterfowl, but also poultry. “The current variant has adapted well and goes around the world with birds,” explains Kuiken. If mammals eat an infected bird, they can also get sick.

So far, we’ve only seen mammals get infected through that route, says virologist Kuiken. At the moment it does not appear that mammals transmit the virus to each other, but we are not entirely sure. “At the same time, we’ve now counted a hundred cases in the United States, across thirteen mammal species. That’s a lot,” says Kuiken.

Virology professor Wim van der Poel (Wageningen University & Research) shares these concerns. “We are dealing with a virus that continues to circulate. And with this we have a permanent risk that variants will emerge that are also infectious to humans.”

Every time a virus “jumps,” there’s a chance for a mutation. If more animals are infected, there will be more mutations. And the more mutations, the greater the possibility that a variant that is also contagious for humans will arise.

It happened before. Kuiken: “In 2013 in the Netherlands, we saw that it was transmitted from person to person, which was again a different variant. People who worked on poultry farms then transmitted the flu virus to their roommates at home.”

The avian flu currently circulating in the Netherlands, a severe variant, has already been diagnosed in humans, says Kuiken. “It almost always involves people cleaning up on poultry farms.” The virus is found in their nasal cavity.

Infections in 2013 did not spread widely among people, also because infected people were placed in isolation early. But according to Kuiken, that was more luck than wisdom. “In reality, we’re balancing on a tightrope. It can really go wrong, to the point where people are actively infecting each other.” A forthcoming pandemic is therefore not inconceivable. For example, researchers suspect that the Spanish flu reached humans through birds.

Wageningen University, to which Van Der Poel is affiliated, does a lot of research on bird flu. Part of that search consists of sequencing. The genetic composition of the virus is examined, so that new variants can be detected, as is the case with the corona virus. The results of those studies have so far been better than expected, says Van Der Poel.

“The risk is not great at the moment, but if bird flu continues to circulate, we could end up in a situation where the virus moves from mammals to humans or spreads between people,” says Van Der Poel.

Virologist Marion Koopmans also warned of bird flu in Buitenhof early last year. You spoke of a “permanent threat of a pandemic”. “We have several examples of pandemics that have originated from flu viruses in the past. You have to be careful about that.”

In the short term, experts say, poultry could be vaccinated. Wageningen Bioveterinary Research (WBVR) is currently studying three vaccines on behalf of the Ministry of Agriculture.

‘There is a huge demand for vaccination, but it is not the case that there is an ideal vaccine that provides complete protection,’ says Professor Van Der Poel. This has to do with the quality of the vaccine on the one hand, but also with the way it is administered. “You’d rather have a vaccine that can be delivered through the air than have to vaccinate animals one by one. But we don’t have such an ideal vaccine yet.”

Kuik: “Our approach now is simply to trust that such a change in the virus won’t happen. But we are increasing the chances of it happening, for example by keeping thousands of chickens together in large barns.”

The two experts argue for vaccines, but also for a different way of raising poultry. Van Der Poel: “In that sense, we should have been warned about the coronavirus. Influenza is a candidate for the next pandemic.”