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.