Study Uncovers Human-to-Cat Transmission of SARS-CoV-2

Dawn O'Shea

April 23, 2021

Researchers led by the University of Glasgow Centre for Virus Research have identified SARS-CoV-2 in respiratory samples from cats, associated with human-to-cat transmission.

The team tested for SARS-CoV-2 antigen in tissue samples from cats using immunofluorescence and for viral RNA by in situ hybridisation. A set of 387 oropharyngeal swabs that had been submitted for routine respiratory pathogen testing was tested for SARS-CoV-2 RNA using reverse transcriptase quantitative PCR.

Lung tissue collected post-mortem from cat 1 tested positive for both SARS-CoV-2 nucleocapsid antigen and RNA. SARS-CoV-2 RNA was detected in an oropharyngeal swab collected from cat 2 that presented with rhinitis and conjunctivitis.

High throughput sequencing of the viral genome revealed five single nucleotide polymorphisms (SNPs) compared with the nearest UK human SARS-CoV-2 sequence, and this human virus contained eight SNPs compared with the original strain.

An analysis of the viral genome of cat together with nine other feline-derived SARS-CoV-2 sequences from around the world revealed no shared cat-specific mutations.

These findings indicate that human-to-cat transmission of SARS-CoV-2 occurred during the COVID-19 pandemic in the UK, with the infected cats developing mild or severe respiratory disease.

The team say, given the ability of SARS-CoV-2 to infect different species, it will be important to monitor for human-to-cat, cat-to-cat and cat-to-human transmission.

This is the first report of human-to-cat transmission of SARS-CoV-2 in cats in the UK. The study is published in Vet Record.

'Important and Interesting Findings' 

Experts have commented on the study via the Science Media Centre.

Professor James Wood, head of Department of Veterinary Medicine, University of Cambridge, said: "These are important and interesting findings, adding to the body of evidence that humans can infect their pets, in some cases, as here, leading to clinical disease in the animals."

He added: "Careful monitoring of the health of animals in contact with human patients is warranted and owners should follow advice, where possible, to try to separate themselves from their animals when they are clinically unwell."

Eleanor Riley, Professor of Immunology and Infectious Disease, University of Edinburgh, said: "Importantly, to date, there is no evidence of transmission from domestic cats back to their owners.

"However, it is vitally important to monitor SARS-CoV-2 infections in animals, both domesticated and free-living, as they offer a potential reservoir for virus persistence,  mutation and re-emergence into the human population."

Hosie MJ, Epifano I, Herder V, Orton RJ, Stevenson A, Johnson N, MacDonald E, Dunbar D, McDonald M, Howie F, Tennant B, Herrity D, Da Silva Filipe A, Streicker DG, COVID-19 Genomics UK (COG-UK) consortium, Willett BJ, Murcia PR, Jarrett RF, Robertson DL, Weir W. Detection of SARS-CoV-2 in respiratory samples from cats in the UK associated with human-to-cat transmission. Vet Rec. 2021 Apr 23 [Epub ahead of print]. doi: 10.1002/vetr.247.

This article was adapted from Univadis, part of the Medscape Professional Network.

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