‘Risk-based bird flu mitigation’ – Poultry World

In the summer season of 2021, Dr Janneke Schreuder, veterinarian and epidemiologist at Utrecht College, received her doctorate on a broader technique to protecting against hen flu.

“This undertaking is section of our normal study theme listed here at Utrecht University that focuses on infectious ailments in animals,” states Professor Arjan Stegeman, who supervised Janneke Schreuder’s PhD thesis. Stegeman chairs the Farm Animal Well being division at Utrecht University, which has been conducting investigation into avian influenza considering that 2003 when the very first significant chook flu outbreak strike the Netherlands. “In that individual outbreak the condition began as a low pathogenic virus variant, inducing gentle disorder on a person farm. From there it mutated into a highly pathogenic variant, spreading to huge sections of the Dutch poultry market.”

The point that the fowl flu virus has been equipped to distribute so rapidly around the globe since the 1990s is also thanks to the tremendous improve in the scale and density of poultry farms in specified elements of the world, in the professor’s watch. “Another reason is that the vaccines that are often utilised really don’t guard from the unfold of the virus, significantly like the coronavirus vaccines in human medicine.”

Chance maps with hazard places

The avian influenza variant of most problem is H5N1, a very pathogenic variant. According to Stegeman, the dilemma is that wild bird populations grew to become increasingly resistant to this virus pressure simply because they are constantly uncovered to it. When the H5 virus jumped from poultry to migratory birds in Asia for the initial time, it caused sizeable difficulties.

“However, as it turned out, over time the wild birds did not always die instantly after infection, letting for the choice of variants that could persist in these populations. In the breeding areas, in Siberia, for illustration, Asian migratory birds come into speak to with migratory birds from Europe. In this way those variants could distribute more from Asia to Europe,” suggests Stegeman.

”…the chicken flu virus can mutate incredibly quickly.”

More than time, some wild birds became carriers of the hugely pathogenic variants. Meanwhile, there are now also other H5 variants in circulation in wild bird populations, this kind of as H5N2, H5N6, H5N8. When wild birds are infected, they possibly die or they grow to be resistant and can act as a reservoir from which professional poultry can be infected. “The system of the condition in professional poultry is so acute that they succumb without warning.”

A different tricky detail about the fowl flu virus is that it can mutate quite rapidly. This is simply because numerous fowl species migrate to accumulating locations and then infect every single other. That is why one particular of the components of Schreuder’s investigate was to execute chance analyses. Dr Fred de Boer of Wageningen University served Schreuder with producing these risk maps with threat areas. The hazard maps for bird flu have presently been finished for the Netherlands and De Boer is now setting up to map the risk regions for Europe, too.

“You can see on these maps exactly where the high and reduced chance areas are, parts which are linked with high or lower densities of selected wild bird species that are known to be superior host species for highly pathogenic avian influenza viruses,” reported Stegeman, who thinks that these risk maps could be utilized by poultry farmers, for case in point, to set up new farms in locations in which the hazard of infection from wild birds is comparatively modest. Governments could also use these maps in assist of their permit plan when assessing new poultry assignments.

Predictive product

For research into in which wild chook populations flock alongside one another, Schreuder applied info from Sovon, the Dutch Centre for Discipline Ornithology. This organisation collects pretty detailed knowledge on the densities of chook species. “Schreuder applied this knowledge to analyse the distribution of 54 wild bird species, largely geese and ducks, as nicely as birds of prey. These success were put together with info from bird flu outbreaks concerning 2014 and 2018. Subsequently, the PhD pupil designed a product that enables you to forecast the place the pitfalls of an outbreak are best. Centered on that design, a hazard map was made for the Netherlands,” reported Stegeman, incorporating, “We also made use of the model for the most recent outbreaks in 2020 and even people in 2021. Quite interesting, simply because then you can definitely see the product at operate.”

What also emerged from the PhD student’s investigate is that some chook species often transmit extra virus than other species. “As indicated, there are now many really pathogenic virus variants in circulation all about the environment. Having said that, which variety is dominant and how sick birds turn out to be, may differ from 12 months to calendar year. In 2020-2021 a lot of wild geese in the Netherlands became contaminated with fowl flu, as did scavengers, these kinds of as birds of prey. In other a long time it was various species, like wigeons or tufted ducks.” This info can also be involved in the once-a-year possibility maps.

The truth that the model and the risk maps supply a great indicator of wherever the possibility of outbreaks is best is beneficial, suggests the professor. “However, it is still challenging to predict the precise transfer of an infection from wild birds to poultry. To be ready to say something about causality, you would have to look at the nearby circumstances: the landscape, the genuine existence of migratory and resident wild birds, and no matter whether they are contaminated. The actions of people and the position of mice, rats or other animals, for case in point, all around poultry farms may well also have an affect.”

Actual time future

In the water-rich Netherlands there is now an skilled group on animal conditions that advises the Dutch Ministry of Agriculture on avian influenza mitigation actions. Stegeman: “The Ministry is currently applying the risk map that has emerged from our product. In addition, our investigate has revealed that mortality in laying hens is a extremely sensitive evaluate for early detection of chook flu infections, along with mortality in blend with clinical indicators in meat ducks. This information usually means that firms and veterinarians can recognise hen flu much more quickly.”

As the professor notes, the research also shows how urgent the matter is and how essential it is that you preserve a near eye on even the smallest variations in animal health and fitness on a farm.

Stegeman believes that it might be needed to glance at how a much better unfold of poultry farms globally can be achieved. Another component which could also be examined is wherever the biggest threat areas are. For example in the vicinity of destinations wherever broad numbers of waterfowl obtain. “Ideally, that would not be a place to start off a poultry farm,” suggests the professor. “You ought to also try to reduce an agglomeration of poultry farms in other ideal destinations.”

If you set all the possibility indicators alongside one another on threat maps, in theory, you could develop a true-time electronic threat map. Poultry farmers and governments could go to a web-site to verify this map and promptly see which space(s) or location(s) are now most at chance of chicken flu infection. Technically it is probable to develop dynamic, real-time threat maps of this type but the current chance map is static and was drawn up on the basis of the readily available knowledge, pooled around quite a few many years. “So there is nevertheless some do the job to be performed ahead of serious-time threat estimates ­become available,” Stegeman concludes.