An outbreak of SARS-CoV-2 with high mortality in mink (Neovison vison) on multiple Utah farms

Abstract

The breadth of animal hosts that are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and may serve as reservoirs for continued viral transmission are not known entirely. In August 2020, an outbreak of SARS-CoV-2 occurred on five mink farms in Utah and was associated with high mink mortality (35–55% of adult mink) and rapid viral transmission between animals. The premise and clinical disease information, pathology, molecular characterization, and tissue distribution of virus within infected mink during the early phase of the outbreak are provided. Infection spread rapidly between independently housed animals and farms, and caused severe respiratory disease and death. Disease indicators were most notably sudden death, anorexia, and increased respiratory effort. Gross pathology examination revealed severe pulmonary congestion and edema. Microscopically there was pulmonary edema with moderate vasculitis, perivasculitis, and fibrinous interstitial pneumonia. Reverse transcriptase polymerase chain reaction (RT-PCR) of tissues collected at necropsy demonstrated the presence of SARS-CoV-2 viral RNA in multiple organs including nasal turbinates, lung, tracheobronchial lymph node, epithelial surfaces, and others. Localization of viral RNA by in situ hybridization revealed a more localized infection, particularly of the upper respiratory tract. Whole genome sequencing from multiple mink was consistent with published SARS-CoV-2 genomes with few polymorphisms. The Utah mink SARS-CoV-2 strains fell into Clade GH, which is unique among mink and other animal strains sequenced to date. While sharing the N501T mutation which is common in mink, the Utah strains did not share other spike RBD mutations Y453F and F486L found in nearly all mink from the United States. Mink in the outbreak reported herein had high levels of SARS-CoV-2 in the upper respiratory tract associated with symptomatic respiratory disease and death.

The origins and molecular evolution of SARS-CoV-2 lineage B.1.1.7 in the UK

“…Further, it is unlikely that a variant so effective at spreading in the human population would have evolved in a non-human population; as the mutations required to be successful in a human population may well be different due to differences in cell receptors, as well as behaviour. Common mutations appear in animal populations, such as N501T and Y453F in mink across different continents (Eckstrand et al 2021; Lu et al 2021), but are rarely found in human infections, and not in any of the VOCs. While it would be possible for a two-step evolutionary process wherein there is first some adaptation in an animal population, allowing the crossing of a fitness valley, followed by spillover and human adaptation through conventional transmission, it would once again be difficult to explain the intermediate sample we observe through this transmission process.…”

High Seroprevalence of SARS-CoV-2 in White-Tailed Deer (Odocoileus virginianus) at One of Three Captive Cervid Facilities in Texas

“…The industry is particularly important in Texas where the deer hunting and breeding industry generates over $1.6 billion in economic activity annually ( 16 ). Given the recent findings of wild white-tailed deer infection with SARS-CoV-2, combined with the precedent from mink that captive animal facilities may be high risk transmission environments ( 17 – 19 ), our objective was to investigate the SARS-CoV-2 exposure and infection status of captive cervids in Texas.…”

The Complexity of SARS-CoV-2 Infection and the COVID-19 Pandemic

“…Between April 26 and November 22, 2020, 14 outbreaks of COVID-19 occurred on commercial mink farms in Utah, one outbreak in a commercial mink farm in Wisconsin, and another in Oregon, USA (United States of America). Clinical signs included respiratory signs and sudden death from a total of 12,330 deaths among 145,757 susceptible animals ( Eckstrand et al, 2021 ).…”