STRATEGY ▶▶▶
It is still hard to predict the exact transfer of infec- tion from wild birds to poultry. To be able to say something about causality, you would have to examine the local conditions.
some bird species sometimes transmit more virus than other species. Stegeman: “As indicated, there are now various high- ly pathogenic virus variants in circulation all over the world. However, which type is dominant and how sick birds become, varies from year to year. In 2020-2021 many wild geese in the Netherlands became infected with bird flu, as did scavengers, such as birds of prey. In other years it was different species, like wigeons or tufted ducks”. This information can also be included in the annual risk maps. The fact that the model and the risk maps provide a good in- dication of where the risk of outbreaks is greatest is useful, says the professor. “However, it is still hard to predict the ex- act transfer of infection from wild birds to poultry. To be able to say something about causality, you would have to examine the local conditions: the landscape, the actual presence of migratory and resident wild birds, and whether they are in- fected. The movements of people and the role of mice, rats or other animals, for example, around poultry farms may also have an influence.”
Real time future In the water-rich Netherlands there is now an expert group on animal diseases that advises the Dutch Ministry of Agricul- ture on avian influenza mitigation measures. Stegeman: “The Ministry is already using the risk map that has emerged from our model. In addition, our research has shown that mortality
8 ▶ POULTRY WORLD | No. 1, 2022
in laying hens is a very sensitive measure for early detection of bird flu infections, along with mortality in combination with clinical signs in meat ducks. This knowledge means that companies and veterinarians can recognize bird flu more quickly.” As the professor notes, the research also shows how urgent the topic is and how important it is that you keep a close eye on even the smallest changes in animal health on a farm. Stegeman believes that it may be necessary to look at how a better spread of poultry farms worldwide can be achieved. Another aspect which could also be examined is where the greatest risk areas are. For example in the vicinity of places where vast numbers of waterfowl gather. “Ideally, that would not be a place to start a poultry farm,” says the professor. “You should also try to prevent an agglomeration of poultry farms in other suitable locations.” If you put all the risk indicators together on risk maps, in prin- ciple, you could create a real-time digital risk map. Poultry farmers and governments could go to a website to check this map and immediately see which area(s) or region(s) are cur- rently most at risk of bird flu infection. Technically it is possi- ble to create dynamic, real-time risk maps of this kind but the present risk map is static and was drawn up on the basis of the available data, pooled over several years. “So there is still some work to be done before real-time risk estimates become available,” Stegeman concludes.
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