Sneezing Hamsters Likely Sparked Covid-19 Outbreak In Hong Kong
Imported pet hamsters probably carried the Delta variant of coronavirus into Hong Kong and caused an outbreak among humans, according to a new study.
The researchers from the University of Hong Kong and government officials conducted a genomic analysis of viral samples from the rodents to confirm the fear that a pet shop was the source of the Covid-19 outbreak.
Hamsters are the only second animal known to be able to infect humans. While transmission of Sars-CoV-2 from humans to other mammals have been reported, there was no previous documentation, with the exception of farmed mink, of these animals infecting humans. After a pet store worker tested positive for Covid-19, animals in the store and in the warehouse supplying it were tested for evidence of Sars-CoV-2 infection.
The viral swabs and blood samples from pet animals were tested by RT-PCR and serological assays, respectively. The positive samples from the RT-PCR test were further studied by full genome sequencing analysis. The study showed that 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,” the study said.
According to the study, over 50% of Syrian hamsters tested from the pet shop and warehouse were found positive for Sars-CoV-2 infection. The dwarf hamsters, rabbits, Guinea pigs, chinchilla and mice were tested negative for the virus. The viral genomes deduced from human and hamster cases belonged to the Delta variant of concern that had not been circulating locally prior to this outbreak.
Researchers said that the sequences were 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,” it said.
The Hong Kong study is yet to be peer-reviewed and is available in pre-print.