Low amounts make the animals seriously ill, and fast testing can detect the infection in some cases.
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| In January, Hong Kong culled hamsters for sale or recently purchased from pet shops after a cluster of human cases cropped up around a shop where the rodents tested positive for the coronavirus that causes COVID-19. This hamster escaped the cull thanks to volunteers who adopted it. LOUISE DELMOTTE/GETTY IMAGES NEWS |
According to a new study, golden Syrian hamsters are extremely vulnerable to the coronavirus that causes COVID-19.
While the species is popular among pet owners, Anne Balkema-Buschmann, a veterinarian at the Friedrich-Loeffler-Institut in Riems, Germany, believes the findings, which were published on bioRxiv on April 20, do not cause for concern. "This paper's message is not that hamsters are ticking time bombs that can no longer be maintained in homes." Researchers can fine-tune trials that employ hamsters to test possible COVID-19 treatments by determining how sensitive the animals are to SARS-CoV-2.
The hamsters made headlines in January when a cluster of COVID-19 cases in humans was discovered near Hong Kong pet stores. The government slaughtered almost 2,000 animals as part of their "zero-COVID" goal. Infected hamsters had transferred the delta type of the virus to people twice, resulting in at least one further human-to-human transmission, according to viral genetic analyses. This is the sole documented incidence of the virus spreading from animals to humans, save from a case of mink-to-human transmission in Denmark and a suspected case of white-tailed deer-to-human transmission in Canada.
Hamsters can spread the virus to their uninfected siblings and show pneumonia symptoms that are similar to those seen in people. As a result, rodents, notably Golden Syrians (Mesocricetus auratus), have emerged as a suitable animal model for COVID-19 medication and vaccine development since the early days of the epidemic.
Balkema-team Buschmann's wanted to know how much the SARS-CoV-2 virus makes the animals sick and shed the virus so they could better construct their own COVID-19 vaccination and therapeutic tests. The minimal infectious dose for hamsters is 1/5000th of some prior estimates and 1/100,000th of the minimum infectious dose for humans, according to the researchers.
The virus infected the animals' lungs and multiplied in their nose and throat at this low dose. Rapid examinations of oral swabs from the animals revealed positive results when the lowest dose was increased by a factor of 100, and the animals developed pneumonia and lost weight. There was also a delay of a few days before the animals began shedding viruses and displaying disease symptoms, which could lead to hamster cases going undiagnosed. Other hamster species that can pick up the virus may be at risk, and the animals may shed enough virus to infect people even at low dosages.
The findings offer researchers a more accurate chronology of disease progression in hamsters, which could lead to lower hamster virus dosage levels in medication and vaccination trials to better reflect what happens in humans. If a human in the family tests positive for the virus, the lesson for pet owners is to practice proper hygiene around hamsters and visit a veterinarian. If your pet hamster's mouth is swabbed, you might be able to identify if it's diseased.
"We don't believe hamsters play a role in pandemic dynamics based on these findings." "It's only that if an infected individual comes into close touch with a hamster, the virus could ping-pong around the house," says Balkema-Buschmann.
Hamsters in farmed or pet trade settings, according to Leo Poon, a virologist at the University of Hong Kong who researched the pet store cluster, pose a bigger threat. "With such a high vulnerability to SARS-CoV-2, an infecting hamster introduced to a hamster farm or a batch of hamsters could generate a population outbreak," Poon warns. "Worse, it could be spreading quietly."
The latest hamster study looked at two genetic forms of the virus from hamsters given high and low dosages of the virus, respectively. There were no substantial mutations in either of them. When a virus spreads between species, there's a chance that it could mutate and become more contagious or harmful (as we've seen in humans), but Poon points out that numerous rounds of infection would be required to determine the risk of mutation in these hamsters.
CITATIONS
C. Blaurock et al. Compellingly high SARS-CoV-2 susceptibility of Golden Syrian hamsters suggests multiple zoonotic infections of pet hamsters during the COVID-19 pandemic. bioRxiv.org. Posted April 20, 2022. DOI: 10.1101/2022.04.19.488826.