Nearly five years later, the world still doesn’t know exactly how the coronavirus pandemic, which has killed more than seven million people and has been the worst of the century, began. The clearest clues lead to an unfortunate chain of contacts between wild animals, probably bats, and intermediate species that ended up for sale in markets in Wuhan, China.
Today, an international team of scientists is offering new insights into where and how the next pandemic may be brewing. Researchers have analysed the organs of 461 animals from dozens of species raised on fur farms in China, one of Asia’s leading producers. All of the animals had died for unknown reasons.
The results reveal the presence of more than a hundred different viruses, many of them unknown. Among them, there are 39 that the authors describe as “high risk”, as they have the ability to jump between species and potentially reach humans. The research describes several viruses from wild animals that have infected domestic species, often raised by the thousands in overcrowded cages and without sanitary controls. The samples were collected between 2021 and 2024 in more than a dozen provinces, mainly the four with the highest fur production – Hebei, Shandong, Heilongjiang and Liaoning, in the northeast of the country. The results are published today in the journal Nature, a benchmark for the best science in the world.
One of the authors of the study is British virologist Edward Holmes, who announced to the world on January 10, 2020 the genetic sequence of the coronavirus that causes Covid-19. Since then, he has been one of the greatest defenders of the theory that the pandemic virus originated in bats and reached humans through other carrier animals sold in Chinese markets. He also took an iconic photo of a caged raccoon dog for sale in Wuhan in 2014.
“Farming animals for fur is an obvious way in which a pandemic coronavirus, or a flu virus, could emerge in humans,” Holmes tells this newspaper. researcher from the University of Sydney (Australia), highlights: “Our study shows that viruses have jumped from wild species to farm animals. Because humans are in close contact with these animals, there is also a risk of contagion, and in fact we see that some human viruses have been transmitted to animals.” Researchers have not detected cases of infection between people so far.
Raccoon dogs, a member of the fox family, are nocturnal carnivores that are bred by the millions on Chinese fur farms for their fur trade. Another coronavirus that emerged in China in 2002 and killed nearly 800 people, the severe acute respiratory syndrome (SARS) virus, has also been detected in an animal market in Guangdong. in raccoon dogsThe new study identifies this mammal, along with minks, guinea pigs, rabbits and Arctic foxes, as the largest carriers of “high-risk” viruses for humans.
Among the isolated pathogens are viruses from many families, including coronaviruses and influenza. The most “worrying” of these, according to Holmes, may be the coronavirus HKU5, originating in the common bat and found in minks that died of pneumonia, the British researcher points out. This pathogen is related to MERS, which has been detected in 27 countries and killed almost 900 people since 2012. The jump from bats to minks is “alarming,” Holmes points out, and requires monitoring.
The paper is being published just as the world is experiencing the worst avian flu epidemic ever recorded. A new, highly pathogenic H5N1 virus emerged in wild birds in 2021. It has since spread to domestic birds, forcing the culling of hundreds of millions of birds, infected wild and domestic mammals, especially dairy cows in the United States, but also mink on fur farms in Spain, spread to humans, and reached Antarctica, the most isolated and pristine continent on the planet. The scientific community is holding its breath in anticipation of the possibility that during this uncontrolled circulation the virus could gain the ability to transmit efficiently between people, which could lead to a new pandemic.
The study published today, in which several researchers from the Chinese Academy of Sciences and universities in the Asian country also participated, has not detected the highly pathogenic variant of the flu in farm animals, but it has detected others that have infected humans in the past and that must be monitored, warns Holmes, for whom this is only “the tip of the iceberg”. The researcher is blunt: “All fur farms should be closed. They are one of the most likely places for the start of the next pandemic. Although our study has focused on China, there are farms of this type all over the world”. Cases of contagion with covid and H5N1 flu in minks, for example, have severely affected countries such as Denmark, which was the world’s leading producer, Holland or Spain, among others.
During the coronavirus pandemic, the Chinese dictatorship limited international scientists’ access to the markets where the infections probably began. Despite this, a study carried out by Chinese scientists uncovered the constant trade in live wild animals in Wuhan, and another international study demonstrated the existence of DNA from raccoon dogs and coronavirus in the same samples taken at the Huanan market in January 2020. These tests are not enough to clarify the origin of the pandemic or identify the first patient, but they do point to raccoon dogs as a probable intermediate host of SARS-CoV-2.
“We have reached the end of the road in terms of the origin of Covid-19,” Holmes believes. “I am sure that there will be no more data from China, where there is enormous political control, and all the animals involved are already dead. It is possible that in other countries more SARS-CoV-2 viruses will be obtained from bats that are possibly closer to the one that caused the pandemic. I am convinced that there was an intermediate host, but I am afraid that we will never know exactly which one it was,” he laments. Despite everything, the researcher assures that he has not perceived any political obstacles to carrying out the current study on fur farms.
The charismatic virologist Angela Rasmussen, from the University of Saskatchewan (Canada), who was not involved in the study, highlights its relevance. The published data “present a clear risk of emerging viruses due to contact between animals and people on these farms,” she says. This threat remains “unmonitored,” she adds. The scientist explains that it is difficult to know which virus is more dangerous or transmissible knowing only its genetic sequence, although she highlights coronaviruses and influenza, the latter being especially threatening because they reconfigure their genome every time there is contagion between species, which increases the risk of generating epidemics. Rasmussen agrees that all fur farms should be closed, although she does not see it as realistic. “The next best option is regulation of production practices, including increased monitoring of both animals and workers in these facilities, avoiding overcrowding, providing veterinary care, including humane euthanasia for sick animals, and occupational safety standards for employees to reduce the risk of exposure, such as wearing masks,” he added.
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