Introduction
At the end of December 2019, a cluster of undiagnosed human pneumonia cases, centred on the city of Wuhan (Hubei region), China, was reported (Huang, 2020). These cases were all related to a seafood and live animal (including wild animals) market (Xu et al., 2020). They presented clinical and epidemiological characteristics compatible with the Severe Acute Respiratory Syndrome (SARS) (ECDC, 2020). The etiologic agent was identified either directly from patient samples, or from virus cultures grown from patients hospitalised with pneumonia in Wuhan, using high-throughput sequencing. This agent was identified as an unknown β-coronavirus genetically close to SARS-CoV and named SARS-Cov-2 (Coronavirus Study Group of the International Committee for the Taxonomy of Viruses, 2020). The associated disease was named ‘COVID-19’, for Coronavirus disease-2019 (WHO, 2020a). Genetic proximity analyses with known sequences of other coronaviruses indicated that this virus originated in the animal world, i.e. from chiropterans, considered as an animal reservoir (bats), with possible passage through an intermediate host which was initially suspected to be the pangolin (Liu et al., 2020).
SARS-CoV-2 is the seventh coronavirus known to infect humans, and a zoonotic virus such as SARS-CoV and MERS-CoV (Mackenzie & Smith, 2020) (Appendix S1 ). Direct contact, rather than airborne spread, seems to be the main transmission route for SARS-Cov-2 according to contact-tracing studies (Bi et al., 2020; Burke et al., 2020). Evidence indicates that SARS-CoV-2 is transmitted from human-to-human by infectious droplets, i.e. particles >5-10 μm in diameter (Federation of European Heating, Ventilation and Air Conditioning Associations, 2020). Potential airborne transmission (by droplet nuclei, which are generally considered to be particles <5μm) was evidenced by past studies for SARS-CoV-1 (Booth et al., 2005; Yu et al., 2014; Xiao et al., 2017) and more recently for both SARS-Cov-1 and SARS-Cov-2 in experimental conditions (van Doremalen et al., 2020). Additionally, faeco-oral (Wang et al., 2020; Cai et al., 2020; Wu et al., 2020; Woelfel at al., 2020; WHO, 2020b) and ocular (Dockery et al., 2020) transmission should also be considered.
Due to the above-mentioned transmission characteristics, the SARS-Cov-2 spread very quickly across China and worldwide since its first appearance (Wu and McGoogan, 2020). As of June 7, 2020, a total of 213 countries or territories have been affected by COVID-19 worldwide, with approximatively 7 million human cases (including 400,000 deaths) (https://www.worldometers.info/coronavirus/). The transmission dynamic of a disease is generally estimated by the calculation of the basic reproductive number, the so-called R0. In absence of control measures, the R0 is the number of individuals that become infected after the arrival of a primary infected individual in a fully susceptible (naive) population. During the COVID-19 pandemic, and based on 21 estimates, the R0 was between 1.9 and 6.5, including 13 estimates with a R0 between 2 and 3 (Park et al., 2020). This R0 was generally higher than MERS-Cov (Park et al., 2018) and pandemic influenza (Biggerstaff et al., 2014) but of similar magnitude to the previous SARS-CoV (Riley et al., 2003; Lipsitch et al., 2003), indicating a risk of global spread (Riou & Althaus, 2020). However, the R0 is strongly influenced by mitigation measures (mainly effective physical distancing, quarantine and contact tracing) and needs to be less than one to stop the disease spread (Breban et al., 2013).
Recently, there have been reported cases in canids (dogs) and felids (cats, tigers) with possible high seroconversion (e.g. Zhang et al., 2020; Almendros, 2020; Almendros & Gascoigne, 2020; American Veterinary Medical Association. 2020). Furthermore, recent experimental infections indicate a particular susceptibility of bats, cats and ferrets (Sit et al., 2020; Young-Il et al., 2020; Beer et al., 2020). In April 2020, farmed minks also tested positive to the virus in the Netherlands (Oreshkova et la., 2020).
Despite the few cases reported (until now reporting of animal COVID-19 is not mandatory in many countries), in comparison with the scale of infection in the human population, these observations in animals have provoked some violent reactions towards dogs and cats such as the panic abandonment of them (Qiao et al., 2020; Leroy et al., 2020).
The pandemic form of COVID-19 in human population and its probable animal origin and the recent serial of reported cases in pets, poses the question of what are the drivers of COVID-19 emergence in carnivore domestic pets, specifically cats, dogs and ferrets, as they are close companions to humans and the main pet in the household. Currently there are no published articles regarding the drivers of disease emergence in animals, with the exception of the recent study in livestock animals (Bianchini et al., 2020).
Indeed, the aim of this study was to list, rank and cluster drivers of COVID-19 emergence in pets, using elicitation of experts’ knowledge on each driver and on the relative importance between drivers, in a specific domain of interest, and between these domains.