Over 33 000 deer tested for CWD in 2018

In 2018, the Norwegian Veterinary Institute (NVI) analyzed more than 33 000 samples from deer for chronic wasting disease (CWD).

The discovery of CWD in Norway in 2016 led to extensive measures to remove infection and prevent spreading, as well as monitoring the deer population. In March 2018, the last animals in the infected wild reindeer stock in Nordfjella Zone 1 were exterminated by personnel from the National Nature Inspectorate.

The sampling program for CWD continued throughout 2018. A total of 33,649 animals were tested during the year. In 2018, six wild reindeer were found to have the classic, infectious type of CWD, all in Nordfjella zone 1. One moose in Flesberg in Buskerud was found to have so-called atypical abnormal disease (NOR16CWD) which is believed to occur spontaneously in older animals.

It has been decided to re-establish reindeer in Nordfjella zone 1, which is now subject to fallowing for at least five years. Due to the proximity to zone 1, Nordfjella zone 2 is in a special position regarding the clarification of its infection status. In their re-establishment plan, the authorities have decided that zone 2 must be declared infection-free before it can transfer wild reindeer to zone 1.

Following the 2018 hunt, the NVI tested lymph nodes and brain samples for CWD from approximately 480 animals from Hardangervidda, and just under 80 animals from Nordfjella zone 2. Researchers at the NVI estimate that there is an approximately 64 per cent probability that Nordfjella zone 2 is free of CWD and about 67 per cent probability that Hardangervidda is free. The Norwegian Food Safety Authority has set a requirement of 99 per cent to declare the areas free of infection. The figures are based on a statistical calculation of the probability of detecting CWD cases, provided the herds have at least four positive animals.

Prion diseases

CWD is a prion disease like scrapie in sheep or mad cow disease, where the misfolded protein accumulates in the brain and destroys it. The disease is 100 percent fatal to the individuals affected.

The model tool used in the health notification process was recently covered in the renowned scientific journal Methods in Ecology and Evolution.

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