Update on chronic wasting disease (CWD) III

Abstract

The European Commission asked EFSA for a Scientific Opinion: to revise the state of knowledge about the differences between the chronic wasting disease (CWD) strains found in North America (NA) and Europe and within Europe; to review new scientific evidence on the zoonotic potential of CWD and to provide recommendations to address the potential risks and to identify risk factors for the spread of CWD in the European Union. Full characterisation of European isolates is being pursued, whereas most NA CWD isolates have not been characterised in this way. The differing surveillance programmes in these continents result in biases in the types of cases that can be detected. Preliminary data support the contention that the CWD strains identified in Europe and NA are different and suggest the presence of strain diversity in European cervids. Current data do not allow any conclusion on the implications of strain diversity on transmissibility, pathogenesis or prevalence. Available data do not allow any conclusion on the zoonotic potential of NA or European CWD isolates. The risk of CWD to humans through consumption of meat cannot be directly assessed. At individual level, consumers of meat, meat products and offal derived from CWD-infected cervids will be exposed to the CWD agent(s). Measures to reduce human dietary exposure could be applied, but exclusion from the food chain of whole carcasses of infected animals would be required to eliminate exposure. Based on NA experiences, all the risk factors identified for the spread of CWD may be associated with animals accumulating infectivity in both the peripheral tissues and the central nervous system. A subset of risk factors is relevant for infected animals without involvement of peripheral tissues. All the risk factors should be taken into account due to the potential co-localisation of animals presenting with different disease phenotypes. SummaryIn 2018, the European Food Safety Authority (EFSA) was asked by the European Commission to deliver a Scientific Opinion on three Terms of Reference (ToRs) related to chronic wasting disease (CWD): (ToR1) to revise the state of knowledge, considering new scientific data, about the differences: a) between the strains found in different species in North America (NA) and in Europe and b) between the strains found so far in moose, reindeer and red deer in Europe, with the main emphasis on transmissibility (transmission paths), pathogenicity and prevalence of the different strains and susceptibility of the different species/genotypes; (ToR2) to revise the new scientific evidence on the zoonotic potential of CWD, to assess the risk of transmission to humans through the consumption of fresh meat, meat products and offal of cervids and to provide recommendations on possible additional control measures to address the risks identified; and (ToR3) to identify risk factors that can facilitate the spread of CWD in the European Union given the current situation of the disease.To source the relevant data, the extensive literature searches used in ...

Chronic Wasting Disease (CWD) in Sami Reindeer Herding: The Socio-Political Dimension of an Epizootic in an Indigenous Context

“…The biochemical features of the prion found associated with moose were different from the cases in North America and Nordfjella—even though the strains found in Nordfjella also differ from the North American ones (but the prions were located in both CNS and lymph nodes) [ 2 , 4 , 8 , 42 ]. Between March 2016 and August 2020, 27 cases of CWD were detected in Norway: 19 wild reindeer from Nordfjella, 7 moose, and one wild red deer ( Cervus elaphus ) [ 10 , 27 ]. So far, the origin of CWD in Norway remains unknown [ 2 , 40 ].…”

“…In 2017, the Norwegian authorities made a drastic decision: to cull all the 2000 wild reindeer between 2017 and 2018 in the Nordfjella region to sample them and to limit the spread of the disease, especially towards the semi-domesticated reindeer in surrounding regions [ 2 , 8 , 10 , 40 , 43 ]. According to a veterinarian from the Norwegian Veterinary Institute, Norway was ‘lucky’ to find the case of CWD but also fortunate that it happened in Nordfjella because it is an area with natural borders, so without many animal movements with other regions around:…”

“…In 2016, an unexpected case was found in Norway, the first in Europe, and a further 28 positive cases have been found in Norway, Sweden, and Finland since then, including a new case in a second population of wild reindeer in Norway in September 2020 [ 9 ]. However data coverage is rather poor in Fennoscandia, and most knowledge originates from North America [ 10 ]. In the literature, CWD has mostly been investigated and understood through a biological and epidemiological approach, with less social and even less political consideration (however, studies on social impacts of CWD exist with a focus on North America, e.g., [ 11 , 12 , 13 , 14 , 15 , 16 ].…”

p53, A Victim of the Prion Fashion

“…Prion diseases are also called transmissible spongiform encephalopathies (TSE) as they have all the characteristics of infectious diseases, such as transmissibility, species barriers, as well as the existence of strains. Prion diseases are found in several mammalian species, among which cattle, where the mad cow disease pandemic originated in the late 1990s [ 45 , 46 ], and cervids whose wild population is increasingly affected by the chronic wasting disease (CWD) in North America wooded areas and more recently in Europe [ 47 ]. Prion diseases also affect humans with an incidence of 1–2 cases per million.…”

Editorial: The Design of Molecular Tools in Relation to Prions and Their Biosafety

“…The Iberian Prion and International Prion meetings of 2020, that should have been held in Corunna and Goettingen, respectively, have been canceled, and it is unlikely that they will take place in 2021, either. During the last Iberian Prion Meeting we discussed the potential dangers of a new prion zoonosis in the wake of the first cases of Chronic Wasting Disease (CWD) in Scandinavia (Benestad et al, 2016 ; Koutsoumanis et al, 2019 ), keeping in mind that Castelo Branco is located near the Serra da Estrela, home of the largest population of deer in Portugal. CWD does not seem to be transmissible to humans, but what if it is passaged to sheep or cattle sharing grazing lands with the deer?…”