Before the Huanan Market closed in January 2020, 10 of the 653 stalls sold live or frozen wild animals that were caught in the wild or raised on farms. Dwyer explains that animals such as raccoons and rodents are known to be susceptible to infection with the Coronavirus. When investigators examined the market after it closed, none of the meat or animal samples they examined – including frozen carcasses – tested positive for Sars-CoV-2. However, Dwyer says that perhaps not enough samples have been taken to exclude the bodies as a source of infection.
Can Ebola be transmitted through frozen meat?
If frozen or thawed corpses become infected with the virus, they may pose a risk of infection, says Andrew Breed, a veterinary epidemiologist at the University of Queensland in Brisbane. This may be especially true in intermediate host animals, which tend to shed large amounts of the virus because their immune systems are not prepared to fight the infection. Frozen meat from wild animals from Africa has been linked to an outbreak of viruses like Ebola in Africa, so this won’t be the first time, according to Dutch virologist Doezer.
Breed adds that little is known about the condition of the food while it is being transported to the market. “Freezing and thawing greatly reduces the survival of certain types of viruses, including corona viruses,” he says.
However, Dozer and others assert that the SARS-CoV-2 virus likely was first transmitted from a live animal to humans. Most of the wildlife that is traded in China is alive, says Chris Walzer, a veterinarian with the New York City Wildlife Conservation Society. Many of them come to the market from farms in China. “It puts all these distant species spatially in one place, and this gives you more opportunities to generate and spread a new virus,” says Qiuhong Wang, a virologist at Ohio State University.
It will now be interesting to see if workers on wildlife farms who delivered products to markets in Wuhan have antibodies against SARS-CoV-2. This could be, Dwyer says, the key to knowing the ultimate origin of the pandemic.