A recent dairy cow mystery has raised concerns among the World Health Organization (WHO) about the bird flu virus. How long will people remain out of harm’s way?
From one international researchwhich will be presented this weekend at the Annual Congress of the European Society of Clinical Microbiology and Infectious Diseases in Barcelona, shows that 57 percent of international infectiologists believe that a flu virus strain will become the world’s biggest pandemic threat in the foreseeable future.
In second place is ‘Disease 15 percent consider it the most likely cause of a pandemic in the near future.
At the same time, last week the WHO expressed its concern about a flu virus strain that we have known since 1997: bird flu or avian influenza.
How worrying is bird flu for humans?
For about two years now, bird flu has been known as ‘nature’s corona’ because it causes a lot of damage to the animal world worldwide. But how dangerous is it for humans? “Bird flu has been a concern since the 2000s, but the risk to the general population is small,” says virologist and veterinarian Steven Van Gucht. ‘Specifically for Europe, I am even less worried than a year ago because the bird flu in birds here has subsided somewhat. Last year we had a very large bird mortality, also in Flanders. In the United States, people are lagging behind and the virus is circulating widely and is present at the same time spillover to mammals.’
“The flu virus strain that circulates in birds is very difficult to adapt to humans,” adds Gunther Antonissen, professor of veterinary medicine. ‘The receptors for the virus are located much deeper in the respiratory tract in humans, while in birds they are spread over the entire respiratory tract. Under normal circumstances, only people who are exposed to a very large amount of virus, such as poultry farmers and veterinarians, become ill. It concerns a very small number of people and usually the spread stops there. But those people do have a very high risk of dying.’
According to the WHO, that mortality rate is no less than 52 percent. Worldwide, 889 people, mainly in Southeast Asia, have been infected with bird flu in the past 20 years, of which 463 patients have died. “The total number of infections is very low over a long period of time,” Van Gucht qualifies. ‘The high mortality rate is due to the fact that strains that were very deadly were circulating in certain countries in Southeast Asia, such as Vietnam, Laos and China. Many children were also affected because they often play among poultry.’
Will bird flu be the next pandemic?
What are the chances of a deadly bird flu pandemic?
The bird flu virus has been gaining momentum for a number of years. Dairy cows and goats were recently added to the list of species affected by bird flu after some herds in the US were infected following exposure to wild birds.
“That’s a new twist,” says Van Gucht. ‘Normally we only see one spillover in predators that eat birds, such as foxes and minks. We always assumed that cattle, being herbivores, were not that susceptible at all. We now have to reconsider that. The animals may not become very ill, but that is precisely dangerous because we then notice the disease less well. Moreover, there are no regulations for outbreaks in the livestock sector. Cows are not culled preventively, as in the poultry sector. Another important factor is that the virus is also in the milk. To be clear, there is no cause for concern for consumers because milk on store shelves is pasteurized. Pasteurization kills the virus.’
But even traces of the bird flu virus have been found in pasteurized milk reports the US Food and Drug Administration (FDA). He adds that pasteurization normally eliminates pathogens to a level that does not pose a health risk to consumers.
Van Gucht argues for additional research into the dairy cow mystery. ‘How did the transmission of the virus happen? Was it from respiratory droplets in the air or from milking? What food did the animals receive? And can we learn something from it in the European context? That is also important for other countries. Just think of India, where a lot of cattle and birds come into contact with each other.’
Antonissen raises another concern: ‘The more mammals become infected with the virus, the greater the chance that it will evolve to infect humans more easily and pass from person to person. This increases the chance of a widespread problem. The virus itself can undergo a mutation or it can exchange genetic material with other influenza viruses that are currently present in the host. This could result in a new influenza virus that is better adapted to humans.’
“Such a virus adjustment does not necessarily mean the start of a new pandemic, in which we all go into lockdown again,” say Antonissen and Van Gucht. ‘There is no reason to panic. We have known about this virus for a long time, it has been circulating for decades. In itself, a virus mutation is nothing new. The question is what proportions such a change will take. Fortunately, the virus is being monitored very closely, which means that a mutation will quickly come to light.’
Can a flu vaccine save us from bird flu?
An advantage is that the world is no longer unprepared since the corona pandemic, also a respiratory virus. Moreover, we already know about the bird flu virus and we are working on developing vaccines, but according to the WHO we are not yet where we need to be.
“The bird flu vaccine is indeed not yet on the shelves, but we have the tools to produce one, unlike during the corona pandemic,” Antonissen confirms. ‘Just like the human influenza virus, the bird flu virus changes very quickly. So we have to check every year what adjustments are needed to the vaccine.’
‘The possibility of vaccination of poultry is also being fully investigated to prevent mutations and protect both animals and humans. But that will not happen overnight either, we will have to vaccinate bird by bird,” Antonissen concludes.
