How sneezing hamsters sparked a COVID outbreak in Hong Kong.

How Sneezing Hamsters Sparked a COVID Outbreak in Hong Kong Hamsters are only the second species known to have spread SARS-CoV-2 to humans

 

Pet hamsters probably carried the Delta variant of SARS-CoV-2 into Hong Kong and sparked a human COVID-19 outbreak, according to a genomic analysis of viral samples from the rodents. 

The research confirms earlier fears that a pet shop was the source of the outbreak, which has so far infected about 50 people and led to the culling of some 2,000 hamsters across the city. 

Hamsters are highly susceptible to SARS-CoV-2 and so are a popular model for studying the virus. But the Hong Kong study — posted online as a preprint1 and yet to be peer reviewed — is the first to show that hamsters can become infected outside the laboratory, and that they can pass the virus on to both other hamsters and humans. 

 Hamsters are only the second animal known to be able to infect people, after mink. In late 2020, small outbreaks of COVID-19 in people in Denmark and the Netherlands were linked to farmed mink, sparking panic and mass culls. 

 The latest study points to the pet trade as a route for viral spread, says co-author Leo Poon, a virologist at the University of Hong Kong. But “to be fair to the hamsters”, people are still much more likely to be infected by each other than by pets, he says. 

             NEW ROUTE FOR VIRAL SPREAD .

Nevertheless, it is important to monitor the pet trade closely, says Marion Koopmans, a virologist at the Erasmus University Medical Center in Rotterdam, the Netherlands. SARS-CoV-2 could continue to circulate in animals, evolving in unexpected ways, and then spill back into people, she warns, adding that “we don’t need more surprises with this virus”. 

 Hong Kong has maintained a strict zero-tolerance approach to COVID-19, so when a 23-year-old pet-shop worker tested positive for Delta on 15 January, Poon says it was “a bit bizarre”. The last time the city had seen Delta in the community was in October. 

 Within days, public-health officials had swabbed more than 100 animals at the pet shop and another 500 at the warehouse supplying it. They detected SARS-CoV-2 viral RNA or antibodies against the virus in 15 of 28 Syrian hamsters (Mesocricetus auratus), but in none of the dwarf hamsters, rabbits, guinea pigs, chinchillas or mice. 

 The researchers then analysed genomic sequences of samples collected from 12 hamsters and the first 3 infected people, including the pet-shop worker and a visitor to the shop. 

All of the samples contained a variant of Delta that had not previously been detected in Hong Kong and probably originated from the same source. 

 The team also noticed some diversity in the sequences, and concluded that the hamsters were probably first infected in November, before their arrival in Hong Kong, and that the virus had been spreading undetected among the animals, accumulating a few single-nucleotide mutations along the way. 

  JUMPING BETWEEN SPECIES The pet-shop worker and visitor were probably infected on separate occasions, and Poon says there could have been more jumps. 

Most surprising, he says, was that even after replicating in hamsters, the virus could still “transmit between humans quite effectively”.

Global pet trade and spread of infectious disease.

The exotic animal trade is a multi-billion dollar industry, and the US is the world’s leading importer. While the US government is on the alert for well known animal-transmitted diseases, there is no mandatory health surveillance for most animals coming though US ports for commercial distribution.

 Live animal imports could bring new diseases into the US and infect endemic wildlife, with devastating consequences as, for example, was seen with the worldwide exposure of amphibians to Chytrid fungus which resulted in the decline of more than 200 species. 

 The legal commercial exotic animal trade is a booming enterprise that ships ornamental fish, mammals, birds, reptiles and amphibians around the world. 

These pets, livestock and other animals can carry unexpected infectious diseases from their homelands. If these non-native species escape or are released to the wild, they can create epidemics among susceptible endemic wildlife. 

 Four US agencies oversee live animal imports, but there is currently no systematic screening for disease in most live animal imports. The majority of animals processed through American ports for the pet industry fall under the aegis of the US Fish and Wildlife Service, which has no authority to conduct health inspections. 

 Livestock imports are regulated by the US Animal and Plant Health Inspection Service (APHIS), with oversight by the Department of Homeland Security’s Customs and Border Protection. Species known to carry certain diseases (rabies in dogs, or tuberculosis in monkeys, for example) are monitored by the Centers for Disease Control and Prevention. 

 According to a 2010 report from the US Government Accountability Office, a lack of interagency collaboration creates gaps in health surveillance that could leave native wildlife and people exposed to disease. 

These risks could potentially be enormous. A single fungal disease, Chytrid, for example, devastated more than 200 amphibian species worldwide.

 A related pathogen, Batrachochytrium salamandrivorans, originating with the Asian salamander trade, wreaked similar havoc on native populations in the Netherlands and Belgium. 

If this fungus gains a foothold in the US — a salamander biodiversity hotspot — experts fear entire species could be wiped out. continue