A study published in Science returns to investigate the origins of the SARS-CoV-2 coronavirus, illustrating an interesting theory about series of unfortunate events that would have led to the leap of species (spillover) of the virus from animals to humans.
To understand the origins of SARS-CoV-2, we need to go back to 2002 and the spread of the “old” SARS-CoV coronavirus, which infected about 8,000 people in China that year before its race was stopped in 2003. The zoonotic origin was then linked to live wildlife markets, and SARS-CoV-2 also appears to be attributable to wet market Chinese (literally “wet markets”, so called because of the always wet soil), where live wild animals often carrying coronavirus are sold.
Alternative meats. According to the researchers, however, it would have been an event in particular that favored the jump of species, and triggered the fuse that would then have detonated the covid.
The African swine fever, which led to the culling of about 150 million pigs in China alone, in 2019 caused the country’s availability of pork to drop by about 11.5 million tons: in November 2019, prices skyrocketed, with tariffs wholesale more than double compared to 2018.
Consumers, complicit in high prices and limited availability, therefore began to buy other types of meat, including that of wild animals, until then traditionally consumed in particular in southern China. All this has led to a greater sale of that type of meat, a further crowding of wet market and ultimately a higher risk of spillover.
Infected carcasses. But it wasn’t just China’s sudden hunger for bushmeat that fostered the rapprochement between the new coronavirus and our species. To avoid the spread of swine fever, the Chinese government began encouraging the sale of frozen meat in October 2018, and in September 2019 it eliminated taxes on the transportation of frozen pork. The great demand for pork also facilitated the transport (legal and illegal) of other types of frozen meat, such as that of wild animals.
In its report on the origins of the virus, the WHO denounces the presence of wild animal carcasses, in particular badgers, abandoned in the Wuhan market freezers. According to the authors of the study, some infected carcasses, fed to animals that were then themselves sold on the market, could be at the origin of the infection.
“The birth of SARS-CoV-2 has characteristics compatible with a natural species leap”, say the researchers, who underline the importance of not underestimating the role in the spread of the virus of the carcasses of infected animals, and the need to continue to investigate the origins of the progenitor of SARS-CoV-2.