In Norway, CWD was diagnosed in a wild reindeer in March 2016 and in two moose in May and June. The Norwegian Food Safety Authority and the Norwegian Environmental Authority asked VKM for an opinion on factors associated with the introduction of CWD.

The conclusions in the opinion are based on today's knowledge, and upon experiences with CWD from North America.

Unknown origin

There is currently no information that can be used to determine the origin(s) of CWD agents in Norway. The opinion points out that sporadic or genetic occurrence of prion disease in cervids cannot be excluded, nor can introduction from North America or other countries.

Furthermore, there is no evidence that CWD has not been circulating at low levels in the Norwegian cervid populations for years, but has not previously been identified.

Cattle and sheep – very low risk

Genetic variation in the gene that encodes PrP (PRNP) can modulate sensitivity towards CWD. According to the opinion, the levels of such genetic variation in Norwegian wild and semi-domesticated cervids are currently unknown.

Cattle and sheep are at very low risk of developing CWD and it is highly unlikely that prion diseases in sheep or cattle are the origin of CWD.

Transmission to humans

The opinion points out that although transmission of CWD to humans has never been known to occur, and animals other than cervids have not been found to be infected, this possibility cannot be excluded. Thus, measures for reduction of human exposure are recommended.