April 23, 2021

expert reaction to study describing two cases of human-to-cat SARS-CoV-2 transmission

A study published in Vet Record looks at two cases of human-to-cat SARS-CoV-2 transmission in the UK.

Prof 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. Cats and dogs have been reported to be infected. This is a high quality study, including whole genome sequencing to confirm transmission links.

“There is a growing international body of literature that is suggesting that asymptomatic transmission to pet dogs and cats from human patients may take place more commonly than disease is seen in the animals. There has never been any suggestion that the infection may transmit back to humans from their dogs or cats, which in any case is less likely because of scale and hygienic  measures that humans can follow. 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.”

Prof Eleanor Riley, Professor of Immunology and Infectious Disease, University of Edinburgh, said:

“This paper confirms several previous reports of SARS-CoV-2 transmission from humans to their pet cats. Transmission from zookeepers to large cats has also been reported. Most cats seem to get only mild respiratory infections and recover quickly. The report of an apparently fatal infection in a “Ragdoll” kitten is new. A number of health-related issues have been linked to the genetic mutation that causes the Ragdoll phenotype, including heart defects. Whether this, or the very young age of the cat, is relevant here is unknown. It would be unwise to draw any conclusions from a single case.

“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.”

Prof Lawrence Young, Virologist and Professor of Molecular Oncology, Warwick Medical School, University of Warwick, said:

“This study confirms previous anecdotal observations that SARS-CoV-2 infection can be spread from humans to their domestic pets.

Two cats from different households presented with symptoms and were shown to be infected with SARS-CoV-2. Only one of the infected cats had full virus genome sequencing analysis performed which confirmed infection with virus very similar to that circulating in the human population. While it seems to be a rare occurrence, this study is further evidence that infected owners could infect their cat with SARS-CoV-2 and the cat could become symptomatic.

“While there remains no evidence that infected domestic pets can transmit infection to humans, scientists will continue to monitor SARS-CoV-2 infection in a range of non-human species. For examples, a recently published preprint (https://doi.org/10.1101/2021.03.18.436013 doi: bioRxiv) shows that virus variants from South Africa (B1.351) and Brazil (P1) are able to infect mice and replicate to high levels. While this paper does not look at transmission, this raises the possibility that virus variants could be more infectious for other species including cats and dogs which could possibly play a role in animal reservoirs and pose a risk of spill over back into humans.”

Prof Diana Bell, Professor of Conservation Biology, University of East Anglia’s School of Biological Sciences, said:

“These results are not surprising as similar human-to-cat infections have also been reported in low numbers in other countries where the animals typically make a full recovery.”

‘Detection of SARS-CoV-2 in respiratory samples from cats in the UK associated with human-to-cat transmission’ by Margarey Hosie et al. was published in Vet Record at 5:00am UK time on Friday 23 April.

DOI: 10.1002/vetr.247

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www.sciencemediacentre.org/tag/covid-19

Declared interests

Prof Eleanor Riley: “No conflicts.”

None others received.