SARS-CoV-2 in animals used for fur farming: GLEWS+ risk assessment (20 January 2021)

SARS-CoV-2 was first identified in humans in December 2019 and has since affected almost 68 million people causing over 1.5 million deaths worldwide. Animal-to-human and animal-to-animal transmission has been documented within farmed minks in several countries. SARS-CoV-2 has been identified in a farmed mink population in a number of countries. Some of the affected farms reported also workers SARS-CoV-2 infection and it is hypothesized that the mink farms were infected through human-mink transmission proving SARS-CoV-2 capability of reverse zoonosis. This Tripartite Risk Assessment, as a joint effort under the GLEWS+ initiative, completed with the Food and Agriculture Organization (FAO), the World Health Organization (WHO), and the World Organisation for Animal Health (OIE), evaluates the risk of introduction and spread of SARS-CoV-2 within fur farming systems as well as whether farmed fur animals could play a significant role in the spread of SARS-CoV-2 to humans via spillover. Additionally, using a One Health approach, the Tripartite evaluated the risk of the escaped minks leading to the establishment of a viral reservoir in susceptible wildlife populations. This work provides guidance to Members on this newly emerging threat.

Chapter 2 - Severe acute respiratory syndrome (SARS)

In 2002, a severe-to-fatal respiratory disease began in China and was named severe acute respiratory syndrome (SARS). The causative agent was soon found to be a coronavirus and was named SARS-coronavirus (SARS-CoV). Infection was traced to contact with live palm civet cats or raccoon dogs in live animal food markets (“wet markets”) and later, person-to-person. Visiting these markets or restaurants housing these animals before preparing them for customer consumption were among the risk factors for infection in addition to frequent use of taxis and comorbidities. After its initial appearance, SARS spread rapidly through parts of Asia and then to countries around the world before almost completely disappearing in 2003. It caused 8096 cases and 774 deaths. SARS-CoV is a betacoronavirus linage B. The single-stranded RNA genome of coronaviruses is the largest among RNA viruses. The size of the genome, the inaccuracy of replication in most coronaviruses, and homogenous and heterogenous genetic recombination contribute to the high frequency of mutation. The viral spike (S) protein binds to angiotensin-converting enzyme 2 on the host cell before entry. Mutations in the S protein make a substantial contribution to viral transmission to additional host species and cell types in addition to viral virulence as the virus adapted to its new hosts. Interestingly, SARS-CoV isolates from the initial stages of the 2002–2003 epidemic were more virulent than those isolated later and are associated with a 29-nucleotide deletion in the S protein gene. Several insectivorous Chinese bats appear to serve as reservoir hosts for the ancestorial coronavirus. New forms of protection against infection were implemented in China and some other countries and include wearing face masks, thermal screening, and avoiding travel in taxis and public transportation. Their effectiveness in decreasing transmission and the rapid end of the epidemic is unknown.

Virome characterization of game animals in China reveals a spectrum of emerging pathogens

Wild animals may be closely related to the outbreak of infectious diseases in recent years. For example, it has been reported that there are closely related SARS-CoV and new coronavirus (SARS-CoV-2) in civet cats, raccoon dogs and pangolins. Therefore, it is of great significance to identify existing or potential pathogens in wild animals that may be in close contact with humans, in order to trace the origin of a specific epidemic and to carry out risk assessment of the most likely source of future epidemics.

Susceptibility of Raccoon Dogs for Experimental SARS-CoV-2 Infection.

Raccoon dogs might have been intermediate hosts for severe acute respiratory syndrome-associated coronavirus in 2002-2004. We demonstrated susceptibility of raccoon dogs to severe acute respiratory syndrome coronavirus 2 infection and transmission to in-contact animals. Infected animals had no signs of illness. Virus replication and tissue lesions occurred in the nasal conchae.