a threat to humans?

As more animal species susceptible to SARS-CoV-2 infection have been identified under natural or experimental conditions, the risk of zoonosis has been suggested by the National Academy of Medicine from the origin of the pandemic [1]then confirmed when the Netherlands demonstrated the contamination of humans by farmed mink.

Subsequently, several cases of animal contamination by different variants of SARS-CoV-2 of human origin were reported, affecting a variety of species among domestic, livestock (Mustelidae) or wild animals. [2]. Zoo animals (big cats, apes, hippos, otters) were contaminated by their keepers. In India, a wild leopard was infected with the delta variant.

Although the cases of human contamination of dogs and cats are sporadic, the formation of a virus reservoir in nomadic cats remains possible due to their contact with the still poorly studied border fauna of wild origin and the susceptibility of felids to different variants of SARS-CoV-2. Among the new pets, a natural infection in two rabbits with SARS-CoV-2 has been reported in France [3].

In Hong Kong in January 2022, golden hamsters imported from the Czech Republic via the Netherlands would have been the origin of an epidemic by the Delta variant, which began with a pet shop worker before reaching 58 people. Since the breeding mink episode, this is the first time that contamination from human-originated hamsters has been followed by retransmission to humans, then epidemic spread through human-to-human transmission. The hamster’s high susceptibility to SARS-CoV-2 identifies this pet as a potential reservoir. In addition, the investigation conducted in connection with this outbreak shows that the international pet trade poses a risk of long-distance spread of SARS-CoV-2. [4].

In North America, the white-tailed deer (Odocoileus virginiatus) could represent an animal reservoir of SARS-CoV-2. The hypothesis was reinforced in 2022: this overpopulated species approaches urban or suburban areas, which has probably favored its contamination by humans. The seroprevalence of anti-SARS-CoV-2 antibodies in these wild cervids has been estimated to be between 13.5% and 70%, with a peak of 82.5% during the hunting season in the United States [5]. In captive animals it rises to 94.4%, probably due to their promiscuity. In Pennsylvania, where the white-tail deer population is densest (30 deer per square mile), the alpha variant circulated concurrently with the delta variant in the fall/winter of 2021 as the delta variant predominated in the human population. The dynamics of intraspecific transmission was studied experimentally after intranasal inoculation of kids by monitoring contact animals. [6]. Finally, a new, highly divergent lineage of SARS-CoV-2 discovered in white-tailed deer in Canada was isolated from a human case in the same region, suggesting possible deer-to-human transmission. [7].

In Europe, the hypothesis of a reservoir in deer has not been confirmed, but other wildlife species are very sensitive to SARS-CoV-2. This is the case with wild or feral mustelids that are HIV positive: otters and mink in Spain [8]Martens and badgers in Brittany [9]. In France, the epidemic spread of Covid-19 due to the Marseille-4 variant (B.1.160) in 2020 seems to have started from a mink farm in Eure-et-Loir [10]. Several species classified as harmful in France because of their fertility are also very susceptible to SARS-CoV-2: the American mink, the raccoon dog and the red fox.

In the joint statement of March 7, 2022, the OIE, WHO and FAO emphasize the risk posed by the animal reservoir of SARS-CoV-2 and its potential role in the emergence of new variants through mutation or through recombination [11]. In addition, it must not be forgotten that the animal reservoir of the coronavirus at the origin of the Covid-19 pandemic was probably a bat and that in this species coronaviruses very close to SARS-CoV-2 have recently been identified under particular surveillance [12].

Therefore the National Academy of Medicine recommends :

  • maintain continuous surveillance of infections detected in companion animals, wild animals and introducers susceptible to SARS-CoV-2;
  • to perform systematic sequencing for each case found positive by RT-PCR;
  • to warn infected people, whether symptomatic or not, that they must also use isolation measures from animals living in their vicinity;
  • To inform hunters, forest workers and all persons who carry out an activity in contact with wild and liminal animals (professional care centers, zoos, etc.) as well as visitors to animal parks about the zoonotic risks involved.

medical academy

  1. Press release from the National Academy of Medicine and the French Veterinary Academy “Do animals infected with SARS-CoV-2 pose a risk to humans?», July 23, 2020.
  2. Brugère-Picoux J et al. Report “Covid-19 and wildlife, from a still-mysterious origin to a still-uncertain future“. Bull Acad Natl Med 2021; 205:879-90.
  3. Fritz M et al. First evidence of a natural SARS-CoV-2 infection in pet rabbits. Vet Sci 2022; 9, 49
  4. Hui-Ling Ye et al. Transmission of SARS-CoV-2 (variant Delta) from pet hamsters to humans and further spread of the adapted strain in humans: A case study. lancet 2022; 399:1070-8.
  5. Kuchipudi SV et al. Multiple human spillovers and onward transmission of SARS-CoV-2 in white-tailed deer. Proc Natl Acad Sci USA 2022; 119:e2121644119.
  6. Martins M et al. From deer to deer: SARS-CoV-2 is efficiently transmitted and exhibits broad tissue tropism and sites of replication in white-tailed deer. PLoS Pathog 2022; 18: e1010197.
  7. Pickering B. et al. Highly divergent white-tailed deer SARS-CoV-2 with possible deer-to-human transmission. bioRxiv (form).
  8. Aguiló-Gisbert J et al. First description of SARS-CoV-2 infection in two wild American mink (Neovison mink) Caught in the wild. Animals (Basel). 2021; 1422.
  9. Davout B. et al. Detection of antibodies against SARS-CoV-2 in wild mustelids from Brittany (France). bioRxiv (form). https://doi.org/10.1101/2022.01.20.477038
  10. Colson P et al. Analysis of SARS-CoV-2 variants from 24,181 patients illustrates the role of globalization and zoonosis in pandemics. front microbiol 2022; 12:786233.
  11. OIE/WHO/FAO. Joint statement on the priority of monitoring SARS-CoV-2 infection in wild animals and preventing animal reservoirs from forming. 18 March 2022. https://www.oie.int/fr/joint-statement-on-the-prioritization-of-monitoring-sars-cov-2-infection-in-wildlife-and-preventing-the-formation – from-animal-reservoirs/
  12. Temmam S, et al. Bat coronaviruses related to SARS-CoV-2 and infectious to human cells. Nature 2022. doi: 10.1038/s41586-022-04532-4. Epub before printing. PMID: 35172323.

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