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Transmission of SARS-CoV-2 (Variant Delta) from Pet Hamsters to Humans and Onward Human Propagation of the Adapted Strain: A Case Study
19 Pages Posted: 28 Jan 2022
More...Abstract
Background: Transmission of SARS-CoV-2 from humans to other mammals, including pet animals, has been reported. However, with the exception of farmed mink, there is no previous documentation that these infected animals can infect humans, nor of further onward spread among humans. Following a confirmed SARS-CoV-2 infection of a pet store worker, animals in the store and the warehouse supplying it were tested for evidence of SARS-CoV-2 infection.
Methods: Viral swabs and blood samples from pet animals were collected in a pet shop and the warehouse supplying it and tested by SARS-CoV-2 RT-PCR and serological assays, respectively. SARS-CoV-2 RT-PCR positive samples were studied by full genome sequencing analysis.
Findings: Over 50% of individually tested Syrian hamsters in the pet shop (8/16) and warehouse (7/12) were positive for SARS-CoV-2 infection in RT-PCR or serological tests. None of dwarf hamsters (n=77), rabbits (n=246), Guinea pigs (n=66), chinchilla (n=116) and mice (n=2) were confirmed positive in RT-PCR tests. SARS-CoV-2 viral genomes deduced from human and hamster cases in this incident all belong to Delta variant of concern (AY.127) that had not been circulating locally prior. These sequences are highly similar, but distinct. The viral genomes obtained from hamsters are phylogenetically related with some sequence heterogeneity and phylogenetic dating suggest infection in these hamsters occurred around 21 November 2021. Two separate transmission events to humans are documented, one leading to onward household spread.
Interpretation: Pet hamsters can be naturally infected in “real-life” settings. The virus can circulate within hamsters and lead to human infections. Both genetic and epidemiological results strongly suggest that there were two independent hamster-to-human transmission and that such events can lead to onward human transmission. Importation of infected hamsters was the most likely source of virus infection.
Funding Information: This work is supported by US National Institutes of Health (U01AI151810 and 75N93021C00016), RGC theme-based research schemes (T11-712/19-N and T11-705/21-N), InnoHK grants for C2I and D24H, and Health and Medical Research Fund (COVID190205).
Declaration of Interests: None of the authors had competing financial or non-financial interests.
Ethical Approval: Animal samples were collected for clinical diagnosis during a public health investigation led by the Hong Kong Government (AFCD). Specimens from humans were collected and tested by RT–qPCR as part of routine clinical care and the viruses genetically sequenced as part of the routine public health response (Institutional Review Board approval UW20-168).
Keywords: SARS-CoV-2, COVID-19, Pandemic, Zoonosis, Reverse zoonosis, Animal-to-human transmission, Hamster
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