Jumping back and forth: anthropozoonotic and zoonotic transmission of SARS-CoV-2 on mink farms

Abstract

The zoonotic origin of the SARS-CoV-2 pandemic is still unknown. Animal experiments have shown that non-human primates, cats, ferrets, hamsters, rabbits and bats can be infected by SARS-CoV-2. In addition, SARS-CoV-2 RNA has been detected in felids, mink and dogs in the field. Here, we describe an in-depth investigation of outbreaks on 16 mink farms and humans living or working on these farms, using whole genome sequencing. We conclude that the virus was initially introduced from humans and has evolved, most likely reflecting widespread circulation among mink in the beginning of the infection period several weeks prior to detection. At the moment, despite enhanced biosecurity, early warning surveillance and immediate culling of infected farms, there is ongoing transmission between mink farms with three big transmission clusters with unknown modes of transmission. We also describe the first animal to human transmissions of SARS-CoV-2 in mink farms.One sentence summarySARS-CoV-2 transmission on mink farms.

Reverse Zoonosis of COVID-19: Lessons From the 2009 Influenza Pandemic

“…45,46,69 Together with chronology of infection, serologic evidence for infection with pH1N1 or COVID-19 in employees and workers in outbreak areas point out the occupational risk of human-to-animal transmission and vice versa. 10,46 Once the reverse zoonosis events occur, it is crucial to know whether infection is maintained in an animal population and has a potential to spillover back to humans. Therefore, continued serosurveillance in susceptible animals and other animal species in the same area are recommended.…”

Therapeutic MK-4482/EIDD-2801 Blocks SARS-CoV-2 Transmission in Ferrets

“…However, human SARS-CoV-2 cannot productively infect mice without extensive viral adaptation or introduction of human ACE2 into transgenic animals, and none of the mouse models supports transmission to uninfected mice 10 . Spillover of SARS-CoV-2 to farmed minks, subsequent large-scale mink-to-mink transmission and, in some cases, zoonotic transmission back to humans revealed efficient viral spread among members of the weasel genus without prior adaptation [11][12][13][14] . Although mink farms reported elevated animal mortality and gastrointestinal and respiratory clinical signs 15 , outbreak followup revealed continued intra-colony spread for extended periods of time 14 , suggesting that acute clinical signs in the majority of infected animals may be mild or absent.…”

“…Spillover of SARS-CoV-2 to farmed minks, subsequent large-scale mink-to-mink transmission and, in some cases, zoonotic transmission back to humans revealed efficient viral spread among members of the weasel genus without prior adaptation [11][12][13][14] . Although mink farms reported elevated animal mortality and gastrointestinal and respiratory clinical signs 15 , outbreak followup revealed continued intra-colony spread for extended periods of time 14 , suggesting that acute clinical signs in the majority of infected animals may be mild or absent. These mink field reports corroborated results obtained with experimentally infected ferrets showing that mustelids of the weasel genus transmit SARS-CoV-2 efficiently without strong clinical disease manifestation 16,17 .…”

“…, dogs25 and minks 12,14 . Phylogenetic analysis of outbreaks in mink farms revealed prolonged intra-colony circulation and zoonotic mink-to-human transmission14 , driving our selection of ferrets, members of the weasel genus closely related to minks, as a relevant SARS-CoV-2 transmission model. We noted strong viral inoculum amount-dependence of experimental infection of ferrets.…”

End the Lockdown for Animals – Reflecting and Campaigning on Three Key Arenas of Human-Animal Interaction Linked to Zoonotic Diseases.

“…Genetic analysis showed that the mutated variants of SARS-CoV-2 virus were the same as those found in mink and were not identical to those found in unrelated SARS-CoV-2 patients living in proximity of the farms. 16 The World Organisation for Animal Health (OIE) has called on countries "to protect animal health and welfare, and consequently public health" and advised that actions should be taken to "Monitor susceptible animals, such as mink […], as well as humans in close contact with them. Active monitoring is recommended as it might be difficult to detect early infections, especially [in] mink".…”