CWD in Norway

The Norwegian Food Safety Authority (NFSA) and Norwegian Environmental Authority (NEA) asked the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) for an opinion on factors associated with the introduction of Chronic Wasting Disease (CWD) to Norway. VKM appointed a working group consisting of two members of the Panel on Biological Hazards, one member of Panel on Animal Health and Welfare, and two external experts to prepare the answer to the questions. The Panel on Biological Hazards has reviewed and revised the draft prepared by the working group and approved the opinion. CWD was diagnosed in March 2016 in a wild reindeer (Rangifer tarandus) from the Nordfjella mountain area in Norway and in May and June in two mooses (Alces alces) in Selbu in South Trøndelag County, approximately 300 km north from the first case. There is currently no information to determine the origin(s) of CWD agents in Norway. However, the sporadic or genetic (somatic mutation) occurrence of prion disease in cervids cannot be excluded, nor can introduction from North America or other countries. Furthermore, there is no evidence that it has not been circulating at low levels in the Norwegian cervid populations for years, but has not previously been identified. In this scientific opinion, information on prion diseases in general, and CWD in particular, is presented in the light of experiences with this disease in North America. Prions are among the most resilient pathogens known and dissemination of prions into ecosystems is likely to result in long-term problems. Prions bind strongly to soil and remain infectious. In CWD, prions are present in most peripheral organs and also shed into the environment via saliva, faeces, and urine, as well as with the placenta. CWD transmits easily among cervids, either through direct contact, or indirectly via the environment. Migration of animals is relevant for the spread between areas. Strain diversification might occur in CWD and may influence transmission properties of the agents. Clinical signs of CWD are non-specific and do not alone enable confirmation of the diagnosis. Analysis of tissue from the brainstem at the level of the obex by approved methods is necessary for diagnosis of CWD. Prion infectivity is assessed by bioassays, often involving transgenic mice. In vitro conversion assays, like protein misfolding cyclic amplification (PMCA), provide sensitive quantification of converting activity, which is a good approximation of infectivity. Genetic variation (polymorphisms) in the gene that encodes PrP (PRNP) can modulate sensitivity towards CWD. The level of such genetic variation in Norwegian wild and semi-domesticated cervids is 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. Although transmission of CWD to humans has never been known to occur, and animals other than cervids have not been found to be infected, indicating a species barrier, this possibility cannot be excluded. Thus, measures for reduction of human exposure are recommended. Taking into account uncertainties regarding the plasticity of the CWD agents and the lack of transmission data from the Norwegian isolates, this scientific opinion considers the zoonotic risk of CWD to be very low.

Human Pathogens in Marine Mammal Meat

Background: Norway conducts commercial hunts for seals and whales, and since marine mammal meat and products are distributed to the public, these products are covered by the general hygiene control regulations. The control of meat from marine mammals is based primarily on organoleptic and microbiological spot tests. There is a general lack of knowledge available on the presence of potential zoonotic pathogens in marine mammal meat and products and on the potential risk for humans. The Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen; VKM), Panel of Biological Hazards (Faggruppe hygiene og smittestoffer) took the initiative to develop this risk assessment in order to identify possible risks associated with human consumption of meat and products from seals and whales. The risk assessment is based on scientific publications and reports, and documents that have been used for training of veterinary personnel in meat control. Animal welfare is not within the scope of this assessment. Main Conclusions: It is documented in this assessment that marine mammals may harbour several pathogens with the potential of giving disease in humans, and there are some reports on the transfer of such agents via meat from seals and whales. The Panel of Biological Hazards has not been able to document that human consumption of meat from seals and whales is associated to a risk of exposure to human pathogens in Norway, but the data on which this conclusion is build, is scarce and are too limited to draw firm conclusions. There are almost no data documenting the microbiological status of seal and whale meat that is distributed for human consumption and the control is ad hoc, based on spot tests and few animals. The general trend of increased consumption of raw or lightly cooked food may increase the risk for transmission of pathogens to humans. Considered suboptimal conditions for hygienic treatment of meat on board, as compared to abattoir conditions, as well as a long storage time in a non-frozen state (whale meat), it is crucial to secure the hygienic quality of the meat. The training of personnel in slaughter hygiene should be strengthened, and if meat is not frozen, an unbroken cold-chain should be documented through the production line from the slaughter to the retail level. A more systematic meat control practice (routine control) should be established. Broad-scale research projects, focusing on human pathogens in seals and whales, as well as monitoring and collating of data on contamination, are needed to further explore the risks of transmission of human pathogens from marine mammal meat.