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Can Norwegian reindeer provide new insights into chronic wasting disease?
Can CWD spread to other species, including humans? Researchers are now conducting infection trials on reindeer to find answers.
Chronic wasting disease (CWD) is a prion disease that destroys the brains of deer. It is always fatal.
A similar disease is found in cattle, known as mad cow disease (BSE). The most common prion disease affecting humans is Creutzfeldt-Jakob disease (CJD).
In 2016, the Norwegian Veterinary Institute detected CWD in reindeer for the first time, specifically in wild reindeer in Southern Norway. This marked the first confirmed case of CWD in Europe.
International collaboration to study CWD
Norwegian researchers are participating in the international Emerging CWD project, led by Sylvie Benestad, a prion disease researcher at the Norwegian Veterinary Institute.
The project studies how CWD progresses, its potential to spread between deer species, and the risk of transmission to new species, including humans.
With strong ties to the United States and Canada – where CWD has spread widely since the 1960s and 1990s, respectively – the project addresses concerns about death and suffering among wildlife. It has also raised concerns about hunting and the safety of consuming meat from infected animals.
Other deer species, hunting culture, and prion strains
The spread of infectious CWD also poses a risk to moose, red deer, and roe deer.
Trials using pathogens from Norwegian reindeer suggest that extreme caution is needed to prevent CWD from infecting other deer species. If this happens, it could harm both animal welfare and hunting traditions.
Sporadic cases of CWD have been found in Nordic moose and Norwegian red deer. However, these prion strains are believed to be non-contagious between living animals, unlike the strain found in reindeer.
Despite this, all prion strains can cause disease if animals ingest them. Once prions are in the the environment, they remain infectious for a long time, further increasing the risk of spread.
Infection trials on Norwegian reindeer
For the first time, infection trials are being conducted on Norwegian reindeer. Previously, such trials were only conducted with North American reindeer and CWD prions from that region.
"Since the disease is historically new to Europe, there's a significant need for knowledge generated from Norwegian animals and pathogens found in Norwegian wild reindeer," says Jørn Våge, CWD coordinator at the Norwegian Veterinary Institute.
The discovery of CWD in Norway in 2016 prompted drastic measures.
The entire wild reindeer population in Nordfjella Zone 1 was culled and removed, leaving the area vacant and devoid of reindeer.
A few years later, infections were also detected on the Hardangervidda plateau, which is home to Europe’s largest wild reindeer population. Apart from a small forest reindeer population in Finland, Norwegian wild reindeer are the last remaining animals of their kind in Europe.
Carefully selected animals
"We were meticulous in selecting the animals for the trial," says Våge.
He spent three weeks in the field with local reindeer herders to recruit animals.
"The reindeer had to be brought in from the mountains, adapted to feed, socialised to become accustomed to humans and handling, have certain genetic profiles, and be healthy," he explains.
13 female calves from the Filefjell reindeer herd were chosen.
The trial aims to determine whether specific genetic variants are less susceptible to disease development. Only female calves were included to avoid challenges associated with rutting males, as the trial spans several years.
The focus on genetic profiling stems from earlier research on infected populations in Nordfjella, where reindeer with specific gene combinations were found to have a higher risk of CWD infection.
In this research project. the plan is to test five different genotypes. Understanding the significance of genetic variation is important when reestablishing populations or relocating animals.
"The zoonotic potential of CWD – its ability to spread between animals and humans – has so far been assessed as very low. We hope this project will provide a better understanding of this as well, " says Våge.
Santa delivered the reindeer
Våge explains why the research project will be conducted in Canada.
"In Norway, we lack sufficiently large facilities with adequate biosafety levels to conduct such a trial while ensuring good animal welfare. So, we contacted our Canadian colleagues and arranged to use their facilities in Ottawa," Våge explains.
This autumn, the animals were flown to Canada, with layovers in Copenhagen and Toronto.
"Coincidentally, the man who helped us organise the transport of the reindeer to Canada was named Nissen (Santa) by surname. Despite the gravity of the situation, it created a somewhat tragicomic association, as if Santa were flying his reindeer across the Atlantic to Canada, "Våge recalls.
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