Mounting evidence suggests mink farms in China could be the cradle of Covid-19
Durée de lecture : 19 minutesMonde Animaux Chine Covid-19
Could the pandemic have originated in Chinese intensive fur farms ? The « missing link » between bats and humans could well be the mink - though the raccoon dog is also suspected. This would explain why China — leading world producer of fur — appears so determined to tightly control scientific information.
It seems increasingly plausible that Covid-19 originated in fur farms, especially mink, as our investigation shows. At the end of December 2020, Reporterre revealed that the strains responsible for the two epidemic waves that engulfed Europe emerged nearby to a number of large mink farms. Reporterre continued its investigation in China. On 8 January, Science published an article stressing the need to study the link between Covid and mink farms.
- The original article (in French) was published on 8 January 2021. It was translated by Barbara Casassus and Vivienne Crawford Breuil.
For the moment no-one knows for sure if the scientific delegation put together by the World Health Organisation (WHO) will be allowed in to China to investigate the origin of the pandemic.  The ten international experts still have not received the authorisations they need. Negotiations are underway, but no details have been released and it is impossible to predict the outcome.
It is staggering that a year after the start of the last century’s worst pandemic, no progress has been made in understanding how Sars-CoV-2 jumped from bats — its natural host — to humans. This uncertainty is not due to the limits of science, but to the attitude of the Chinese authorities, who for a year have adamantly opposed any independent inquiry — even inside the country — to find the answer. The question is what does China have to hide ?
It is a glaring absence that no inquiry has been made to confirm or deny a seldom mentioned but obvious hypothesis : that the pandemic originated in a fur farm. China is indeed the world’s leading market and leading producer of fur worldwide. The industry in China is worth more than $20 billion a year, and involves more than 50 million animals. Traditional livestock farming for beef, pork or poultry do not seem to be infected by the coronavirus. By contrast, animals bred for their fur, particularly the three main species — mink, fox, and the raccoon dog — are highly sensitive to it.
Specialists know that human epidemics originating from livestock farms are not exceptional. Farms are known breeding grounds for microbes : for example the last flu pandemic, in 2009, originated in American pig farms — hence its name swine flu.
« Coronavirologist » Christian Drosten, who co-discovered Sars-CoV-1 in 2003 and advises the German government, said in an interview with the Guardian in April 2020 « If somebody gave me a few hundred thousand bucks and free access to China to find the source of the virus, I would look in places where raccoon dogs are bred... »
Drosten’s hypothesis that raccoon dogs could be the missing link between bats (the original host of this coronavirus, according to scientific consensus) and humans is common sense. Raccoon dogs (Nyctereutes procyonoides) — often confused with the American raccoons that they resemble — are small carnivorous canids. A team led by Conrad Freuling, from the German Federal Institute of research on animal health in Riems, experimentally demonstrated in August 2020 that not only are these animals infected by the human coronavirus, but that they infect each other.
« We have discovered that the virus remains in the nasal cavities of this animal, and does not reach its lungs », Freuling told Reporterre. « The animals do not get sick when infected, and remain asymptomatic while they are contagious. Moreover, they probably excrete enough virus to infect a human ». This is similar to mink as we saw in Mink farms in Denmark and the Netherlands. Freuling added that transmission without making the host sick is typical of a well-adapted virus, which may confirm the hypothesis that this species could be the « missing link » between bats and humans.
Drosten’s reason for suspecting raccoon dogs dates back to the first SARS pandemic, which began in China in 2002, and spread all over the world in 2003. . It has often been said that the animal spreading the first SARS was the masked civet (Paguma larvata), a member of the viverrid family… but in fact raccoon dogs were also infected and were equally likely to be responsible for the transmission to humans.
Studies carried out in 2003-2004 (notably focused on the markets of Shenzhen, in Guangdong province), show it is nearly impossible to determine which of the two species contaminated the other, or if a third contaminated both at the same time. An article published in Virus Research in April 2007, said the masked civet was the likely intermediate host. But one of the main findings supporting the argument was the contamination of three customers and a waitress in restaurants where live infected masked civets were kept in the dining room. Slim evidence, especially since civets were bred for decades for their fur before becoming a sought-after source of meat, and have seen their population shrink to about 40,000 for the entire country. This compares to a total of 5 million to 10 million raccoon dogs bred in farms during the same period.
In 2003, China seems to have twisted the facts to incriminate the civet, in an effort to divert attention from its fur industry
In winter 2003-2004, an extensive study financed by the Chinese Ministry of Science and Technology and the United States National Institutes of Health, sampled 1,107 civets from 23 farms across 12 provinces. It concluded that 91 civets were infected on the market of Xinyuan (Guangdong), while no infection was found in the farms where the civets came from. This suggests that the contamination could have occurred at the market or during the transport. Moreover, all the 15 raccoon dogs at the Xinyuan market at the same time were infected. Although several articles said the civets could have been contaminated by the raccoon dogs, no studies were undertaken to investigate the raccoon dogs any further. Many researchers, including Paul et Martin Chan, were surprised and regretted that the issue did not « raise more interest ». Shi Zhengli, China’s leading « coronavirologist » and research director at the Wuhan Institute of Virology said in the 2007 article of Virus Research, that it is not « always clear if the raccoon dogs infected the civets or if it is the opposite », before concluding : « Contrary to civets, very few studies have been made on raccoon dogs, wild or farmed. »
Freuling was also surprised. He told Reporterre that he ended up testing transmissibility in raccoon dogs in Germany because this had ever never been done in China, where the vast majority are found. The handful of farms in Europe are in Finland and Poland 
It should be noted that on the Xinyuan markets, foxes and other mustelidae were also infected. Strangely, the Chinese/American study ignored farms in Shandong, Liaoning, Jilin and Heilongjiang, the four most important provinces for mink farms. To have overlooked Shandong area is particularly surprising, because it is the uncontested capital of Chinese fur production, and the province is geographically closer to Guangdong than to Hebei — which was studied.
In 2003, it looks very much as though China manoeuvred to incriminate the civet, a species of marginal economic importance, in order to divert attention from and protect the fur industry. The same strategy seems to have been taken even further in 2020, in a different context, and with enormous stakes at play. This time, China has tried to take total control of both the scientific and public debate on the pandemic. After an initial period of confusion in January-February 2020, when journalists and scientists spoke out and published relatively freely, repression soon took over. A number of journalists were arrested or disappeared, and scientists were censored.
Information and news were evidently filtered and adapted to the needs of the Chinese government
A recent Associated Press (AP) report documents how the Chinese government tried to regain control of scientific publications after a preprint by two researchers was posted online in February. The post, which has now disappeared from the internet , suggested that the virus had escaped from a laboratory in Wuhan. On 24 February, the Chinese Center for Disease Control (CDC) introduced a new approval procedure for publications.
On 3 March, the Ministry of Science issued a confidential note, which AP obtained and published online.
The note calls for « the coordination of scientific research publications on the Covid-19 across the country to be like a “game of chess” », under the control of a « group of scientific researchers from the State Council » and after having informed the Council’s “propaganda team.” The notification prohibits all publication not validated by this group — and states that offenders « would be held responsible ».
Thus when reading recent Chinese scientific publications, it should not be forgotten that despite the excellence of many researchers, the information provided is clearly filtered and modified to suit the Chinese authorities. The same applies to the press : for months there has been no mention of foxes, minks or raccoon dogs being sold on the Wuhan market before it closed on 31 December, 2019.
However, according to the latest WHO report, foxes were being sold on the « wet market » of Wuhan. And the Public Health Agency of Canada said in March that mink were sold there too. Photographs taken in the market by CNN in early December 2019 and published January 2020, showed that raccoon dogs were also present. Whatever the authorities say, it turns out that all three carnivore species were being sold on the Wuhan market.
Despite the Chinese media blackout on these species, the Chinese Minister of Agriculture and Rural Affairs has not forgotten them. Under pressure from world public opinion to prohibit the sale of wild animals on markets, because of the risk of the emergence and propagation of viruses, the authorities reclassified them as « domestic species » in order to prevent any obstacles to breeding them.
As for the pangolin fable, four Chinese scientific articles were published blaming these scaled animals for transmitting the virus to humans, even though the virus had still not been fully sequenced. The pangolin theory has since been abandoned, after it became clear that the pangolin virus was even further from Sars-CoV-2 than the bat virus. Just before these publications, the Chinese authorities had fed the press with the hypothesis that snakes were probably the intermediate host. There was even an attempt to blame turtles. With so many false leads, it is hard not to think that focusing on these three scaled species was an astute tactic to divert public attention from fur farms.
The most plausible intermediate host would be mink, recent research says
While the Agricultural department of Southern University in Louisiana in the United States said, without providing any proof, that the pangolin was responsible for the pandemic, a report taking the opposite view was virtually ignored. On 24 January, 2020, China’s English-language Global Times said that based on GISAID data and artificial intelligence software the most likely intermediate was... mink. It could even have been the original host. This study pointing to mink was set up by the Chinese Academy of Sciences, the Wuhan institute of Virology and the Chinese CDC. The team, led by Quian Guo, is highly respected, the study was well run, and the results were not contested. But its findings were ignored, except in Singapore and Australia. The pangolin, by stirring up passions and reinforcing prejudices, monopolized attention.
Another telling example of the Chinese scientific community’s tactics is the study carried out by the Shandong Medical University and published on 1 April, 2020 in the Medical Journal of Virology. The researchers analysed the structure of the receptor protein ACE2, to which the virus binds when it infects a host, in 85 species of mammals : humans, cats, dogs, pigs, horses, civets, pangolins, macaque monkeys, foxes, raccoon dogs, African elephants, meerkats, bulls, polecats, kangaroos, opossums, tortoises, lynx etc. But the team « forgot » mink, even though at least 15 million of them are bred in the Shandong region where the research originated.
The research concluded — apparently seriously — that a cetacean, « the Finless Porpoise of Yang Tsé, should be monitored because it can be found in the lakes close to Wuhan and could be infected by the Sars-CoV-2 or other closely related coronaviruses ». The study also concluded that small carnivores, including cats, have much less affinity with Sars-CoV-2 than cattle or sheep, whereas we know that the opposite is true.
Over 3,000 mink farms in China, some with over 100,000 animals
In fact, the focus should be on Chinese mink, especially those in Shandong. In recent months, we have learnt from scientists that mink can catch the virus from humans and infect them back, often adding some mutations in the process. But beyond that, a long history of disease in mink shows that in overcrowded intensive farming, this solitary species — like all farmed carnivores, unlike social herbivores —, is sensitive to many diseases and becomes a health nightmare. It is clear that the 3,000 mink farms in China, some of which have over 100,000 animals, could be the source of the current pandemic. It is therefore hard to understand why no viral research has been conducted on them.
On example of the problem was in 2011, when a new virus was discovered in the feces of farmed minks in a farm in Hebei. It seemed to be a virulent combination of usually harmless strains from humans and pigs. All the mink were affected, and 5% died. A necrotizing encephalopathy in two children seemed to be closely related to this recombinant virus, and the study published by Emerging infectious diseases stressed the need to prepare for the emergence of even more virulent variants.
In 2014, Shandong mink farms suffered an outbreak of pseudo-rabies originating from pigs, which led to the death of 87% of the animals and to the spread of the disease to the rest of the province. The scientists trying to evaluate the extent of the outbreak in 14 locations confirmed in their publication that the virus was highly contagious in the region and that « it would be a challenge the fur producing industry ».
In 2015, a team including the Chinese virologist Shi Zhengli isolated and identified viruses from bats that were closely linked to human, pig and mink viruses. This suggests that interspecific transmission exists between bats and humans or other animals.
In October 2016, a team of veterinarians from the Qingdao Animal Science and Veterinary Medicine College discovered that the Shandong minks were contaminated by a very contagious avian flu H5N1.
In 2019, veterinarians from the same college detected in some mink farms in Shandong the emergence of a deadly co-infection virus of canine distemper and H1N1 swine flu, which became a new strain of H1N1 in the infected lungs of these mustelids.
Farmed minks are also possible intermediary hosts for type A Influenza which can lead directly or indirectly to the development of human pandemic strains. They sometimes host an epidemic form of type E Hepatitis virus but it is unclear whether it can affect humans. Minks are also monitored for BSE (Bovine Spongiform Encephalitis) because of the inclusion of animal protein in their diets.
In order to minimize damage, mink are vaccinated against the viruses which affect them most, such as the highly contagious parvovirus of the Aleutian disease, and canine distemper. Minks have fragile lungs. They spontaneously catch lung infections, which they spread easily by sneezing (as do ferrets, also of the mustelid family). Mink, like ferrets, carry specific coronaviruses. The ferret coronavirus is called « systemic », because it attacks all organs, while the mink’s virus is called mink CoV (MCoV).
Bats, attracted to fur farm buildings, frequently defecate on the caged animals
The fertile breeding ground for viruses that these farms represent is measured by the fact that Chinese mink are concentrated mainly in Shandong. This historic fur production region is home to thousands of farms, where different species are often raised together. The animal population totals, 15 million mink, 3 million raccoon dogs and 6 million foxes. Most of them are clustered in a relatively small area, which extends towards the south from the coastal town of Weifang. The animals live crowded together in sometimes appallingly unhygienic situations, are fed partially from fresh fish coming from the Yellow Sea, pig offal, poultry giblets, animal bone meal and carrion of their own species. Large amounts of animal protein are important for the quality of their pelts. Their captive existence is short : mink, for example, reproduce in March, give birth in April and the litters are killed between mid-November and mid-December. The only ones that survive are the males and females necessary to produce the next generation. These reproductive animals account for about 12% of the population of each farm, which is enough for pathogens to persist.
Also important is the fact that Shandong is a mid-mountainous forested region, known partly for its caves that shelter many species of bats, some of which such as Rhinolophus ferrumequinum, are coronavirus carriers. The bats are attracted to the farm warehouses, which provide them with easily accessible shelters. They urinate and defecate often over all that is beneath them, including the cages housing the animals.
So in Shandong, and in other areas of China, all the ingredients exist for powerful viral encounters, recombinations of all kinds, and the rapid emergence and spread of disease.
A little known fact is that in 2019 Shandong produced 6.5 million mink pelts, down from nearly 15 million in 2018. This means nearly 9 million mink disappeared from one year to the next, a 55% drop in production for just one province. Such a sharp decline suggests some form of disaster. Could it have been a health problem ? The production of hides from foxes (5,7 million) and racooon dogs (3 million) remained perfectly stable. The China Leather Industry Association, after several requests for information from Reporterre, explained in an email that « a stagnant market and overproduction » had led to « many companies leaving the industry ». This is hardly enough to explain such a dramatic drop in output.
All major mink fur production centres have been contaminated by Covid-19… except in China ?
It is surprising that officially not a single Chinese mink farm has been contaminated by Covid-19, whereas farms all over Europe—north, south, east and west —and in the United States and Canada have been affected. It would be abnormal for all the large producers in the world to be struck with the disease, except for the largest, despite many commercial links between industry professionals all over the world with the Chinese, especially North America, Northern Europe and Italy.
In short, mustelids, canids et viverrids — the mammals suspected to have an active intermediate role — are the same today as during the first Sars-CoV epidemic in 2003-2004. Except that masked civet are now a thousand times fewer in China than the foxes, raccoon dogs and mink bred for their fur. To establish the truth and avoid another pandemic, it is essential for the WHO to order a very close study of these fur farms in Shandong and elsewhere in China.
From the WHO mission preparatory report, it seems this is the intention, despite careful diplomacy to avoid upsetting the Chinese authorities. It is for example stated that the commission plans to « chart the supply chains of all the animals sold on the market », wild and domestic, in order to identify « the interesting geographic zones in order to control the animal and human serology ». That is precisely what should have been done a year ago : studies to determine the presence of virus in the breeding farms.
Unfortunately, WHO, after many concessions to the Chinese government, abandoned the idea of carrying out the field work and instead signed a protocol delegating that part of the work to local researchers. The mission should not leave the territory of Wuhan, one team member recently told the magazine Science et Avenir, adding that one should not expect, « that the team would come back with a conclusive result ». But even after all these precautions, Beijing still seems to perceive the experts mission as a threat.
The wall erected by the Chinese government seems to be cracking, however. On 8 January, [an article signed by eminent Chinese researchers, Zhengli Shi et Peng Zou, acknowledged for the first time in Science that mink could be the host « of the virus which has become SARS-CoV-2 ». The researchers suggest carrying out « retrospective investigations of samples dating back to before the pandemic on the mink farms and other animals vulnerable to the virus ». Suspicious minds might ask why this suggestion comes so late in the day, when the vulnerability of mink to Covid has been known for six months ; they might also ask if such samples still exist. But others will no doubt say it is better late than never.