(Bloomberg) -- Hong Kong, suspecting that imported hamsters may have spread the virus to humans, ordered the culling of thousands of the small mammals, closed shops selling them and sent more than 100 pet shop visitors into quarantine camp as part of its increasingly fervent quest to eliminate the virus. 

The escalation came after nearly a dozen hamsters imported from the Netherlands and sold at a local pet store called Little Boss were found to be infected with delta, a virulent Covid-19 variant that hadn’t been found in the city for months until a worker there tested positive. Samples from the shop’s warehouse in another part of the city also showed traces of the virus.

All pet shops selling hamsters in Hong Kong -- in total 34 -- were ordered to shut down immediately pending further testing and cleaning, while people who recently bought hamsters were to turn the animals over to authorities for culling. People who bought hamsters specifically from Little Boss will have to go into government quarantine camp. 

About 2,000 small animals, including hamsters, chinchillas and rabbits, will be culled while importation of such creatures has been suspended. 

The hamster furore comes as Hong Kong scrambles to stamp out infection in the city, where dozens of cases have been found after several months without any local transmission. Officials in the financial hub and mainland China, the last places in the world still strictly adhering to the Covid-Zero approach, suspect that frozen food, international mail and animals have played roles in the sporadic flareups slipping through their strict control and tracing efforts. 

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While animals can contract the coronavirus from humans, there hasn’t been any clear evidence that transmission can go the other way. Most animals who have been studied have low viral loads, making it difficult to pass along the pathogen. Cases of humans getting infected after contact with a infected domestic animal are rare.

“Internationally there hasn’t been evidence pets can pass on Covid to humans,” said Sophia Chan, Hong Kong’s Secretary for Food and Health at a Tuesday briefing. “To be prudent, we will take preventive actions against all possible routes of transmissions that can’t be ruled out to decrease the risk of Covid-19 spread.”

The situation began when a pet shop clerk was found to be infected with the delta variant earlier this week. A customer who interacted with the clerk has also been infected, while her husband is preliminarily positive. 

Hong Kong’s hamster cull is its latest escalation of measures, after bars, gyms and cinemas were closed earlier this month to slow omicron’s spread. Authorities have also banned flights from eight countries, on top of mandating 21 days in hotel isolation for most incoming travelers.  

Business groups have said the stringent approach is jeopardizing the city’s status as a financial hub while city officials maintain that it’s necessary to keep infections and deaths to a minimum as they have made opening up travel to mainland China their top priority. 

Animal Risk

Although the origin of the virus is thought to be from a wild animal, either directly from a bat or though an intermediate host like a civet cat or a raccoon dog, domesticated and zoo animals haven’t been implicated in the virus’s spread.  

The first documented case of a pet with Covid-19 was a 17-year-old pomeranian in Hong Kong, who was diagnosed after its owner contracted the virus in February 2020. Testing showed the dog, Loulou, was carrying low levels of the virus and ultimately produced antibodies to it.

Doctors concluded that Loulou, and a German shepherd in Hong Kong who was diagnosed the next month, both had such low levels of virus that they probably weren’t contagious.

Infections have since been confirmed in numerous other animals, including a Siberian tiger named Nadia at the Bronx Zoo in New York. While three African lions and three other Siberian tigers sharing the same enclosures also contracted the virus, none experienced respiratory distress or passed it on to their human handlers. All recovered.

Infected people can pass the virus on to their pets the same way they transmit it to other people, namely the droplets they spray when coughing, talking or even breathing. Direct hand-to-mouth transmission is also possible, French researchers found.

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