a threat to humans?

As more and more animal species susceptible to SARS-CoV-2 infection have been identified in natural or experimental settings, the National Academy of Medicine has suspected a risk of zoonosis since the outbreak of the pandemic. [1]and later confirmed when the Netherlands demonstrated infestation of humans by farmed mink.

Subsequently, several cases of infection of animals with different variants of SARS-CoV-2 of human origin have been reported, affecting a wide variety of species in domestic animals, livestock (mussels) or wild animals. [2]. Zoo animals (big cats, great apes, hippos, otters) have been infected by their keepers. In India, a wild leopard has been infected with the delta variant in the wild.

Although cases of human infection of dogs and cats are rare, the constitution of a virus reservoir in nomadic cats remains possible due to their contact with liminal fauna of wild origin, which is still poorly understood, and the susceptibility of felines to various variants of SARS-CoV-2. Among new pets in France, two rabbits were naturally infected with SARS-CoV-2. [3].

In Hong Kong in January 2022, golden hamsters imported from the Czech Republic via the Netherlands were expected to be the source of a delta variant epidemic that started in a pet store employee and reached 58 people. Since the mink rearing episode, this is the first time that infection of human-origin hamsters has been followed by transmission back to humans and then human-to-human epidemic spread. The hamster’s high susceptibility to SARS-CoV-2 marks it as a potential reservoir. In addition, investigations into this outbreak indicate that the international pet trade poses a risk of distant spread of SARS-CoV-2. [4].

In North America, white-tailed deer (Odocoileus virginus) may represent an animal reservoir of SARS-CoV-2. The hypothesis was confirmed in 2022: this overpopulated species is moving closer to urban or suburban areas, which likely contributed to its infestation by humans. The seroprevalence of antibodies against SARS-CoV-2 in these wild cervids is estimated to be between 13.5% and 70%, with a peak of 82.5% during the US hunting season. [5]. In captive animals, it rises to 94.4%, probably due to their promiscuity. In Pennsylvania, where the whitetail deer population is the densest (30 deer per square mile), the Alpha variant circulated at the same time as the Delta variant during fall-winter 2021 as the Delta variant dominated the human population. The dynamics of intraspecific transmission after intranasal infection of calves was experimentally studied by monitoring contact animals. [6]. Finally, a new highly divergent lineage of SARS-CoV-2 found in Canada in white-tailed deer was isolated from a human case in the same region, suggesting possible deer-to-human transmission. [7].

In Europe, the deer reservoir hypothesis has not been confirmed, but other wildlife species are highly susceptible to SARS-CoV-2. This is the case of wild or feral mustelids found to have HIV: otters and minks in Spain. [8]martens and badgers in Brittany [9]. In France, the epidemic spread of Covid-19 due to the Marseille-4 (B.1.160) variant in 2020 seems to have originated in a mink farm in Aire-et-Loire. [10]. Several species classified as harmful in France due to their abundance are also highly susceptible to SARS-CoV-2: the American mink, the raccoon dog and the red fox.

In a joint statement dated March 7, 2022, the OIE, WHO and FAO highlight the risk associated with the animal reservoir of SARS-CoV-2 and its potential role in the emergence of new variants through mutation or recombination. [11]. In addition, it should not be forgotten that the animal reservoir of the coronavirus at the outbreak of the Covid-19 pandemic was probably the bat, and that coronaviruses very close to SARS-CoV-2 have recently been identified in this species. highly monitored [12].

So The National Academy of Medicine recommends :

  • maintain ongoing surveillance of infections detected in domestic animals, as well as in wild and introduced animals susceptible to SARS-CoV-2;
  • to perform systematic sequencing for each case found positive by RT-PCR;
  • warn infected people, with or without symptoms, that they should also apply isolation measures to animals living in their environment;
  • inform hunters, forestry workers and all those who carry out activities that come into contact with wild and liminal fauna (specialized care centers, zoos, etc.), as well as zoo visitors, of emerging zoonotic risks.

medical Academy

  1. Press release of 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 futureBull Acad Natl Med 2021; 205:879-90.
  3. Fritz M. et al. First evidence of natural SARS-CoV-2 infection in domestic rabbits. Veterinary Science 2022; 9, 49.
  4. Hui-Ling Yu et al. Transmission of SARS-CoV-2 (delta variant) from domestic hamsters to humans and subsequent reproduction of an adapted human strain: a case study. Lancet 2022; 399:1070-8.
  5. Kuchipudi S.V. et al. Multiple side effects from humans and further transmission of SARS-CoV-2 to white-tailed deer. Proc Natl Acad Sci USA 2022; 119:e2121644119.
  6. Martins M. et al. Deer to deer: SARS-CoV-2 is efficiently transmitted and has broad tissue tropism and replication sites in white-tailed deer. PLoS Patog 2022; 18:e1010197.
  7. Pickering B. et al. A highly divergent SARS-CoV-2 white-tailed deer with potential deer-to-human transmission. bioRxiv (preprint).
  8. Aguilo-Gisbert J. et al. First description of SARS-CoV-2 infection in two wild American minks (Neovison mink) Caught in the wild. Animals (Basel). 2021; 1422.
  9. Davout B. et al. Evidence of antibodies against SARS-CoV-2 in wild mustelids from Brittany (France). bioRxiv (preprint). https://doi.org/10.1101/2022.01.20.477038
  10. Colson P. et al. Analysis of SARS-CoV-2 variants in 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 Wildlife and Preventing Animal Reservoirs. March 18, 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 for human cells. Nature 2022. doi:10.1038/s41586-022-04532-4. Epub before printing. PMID: 35172323.

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