Dutch disclose second case of mink-to-human COVID-19 transmission
WAGENINGEN, the Netherlands; WUHAN, China––“A second case has become known on one of the infected mink farms where, most likely, SARS-CoV-2 [COVID-19]passed from mink to human,” Dutch minister of health Hugo DeYoung and minister of agriculture Carola Schouten jointly advised the Dutch parliament on May 25, 2020.
“In the currently discussed case,” DeYoung and Schouten said, “the virus was detected in three people at the infected farm. The genetic code of the viruses shows great resemblance to the genetic codes found in the mink on the farm.
“Based on the information available,” DeYoung and Schouten said, “it is most likely that at least one of the three infected persons was infected by a mink.
“The infection probably occurred,” DeYoung and Schouten speculated, “when it was not yet known that the minks were infected and no personal protective equipment was used.”
So how did cats become involved?
“The [Dutch] National Institute for Public Health & the Environment assesses that the risk of exposure of people to the virus outside the mink building is negligible,” DeYoung and Schouten relayed, but failed to explain how, if COVID-19 virus is securely contained within the mink farms, at least seven domestic cats were apparently also involved in spreading the infection.
Somehow, either infected cats gained access to the mink, or infected mink gained access to cats.
“In total, seven of the 24 sampled farm cats at this farm were found serologically positive,” DeYoung and Schouten said. “This means that these cats have produced antibodies to the [COVID-19] virus.
“In one of the seven positive cats,” DeYoung and Schouten continued, “active virus was also demonstrated,” but in insufficient amount for investigators to determine how the cat was infected, by what species. No virus was detected in the other six seropositive cats. This means that these six cats have had SARS-CoV-2 [COVID-19] infection, but do not excrete the virus any more.
“Infected mink farms have been advised to ensure that their cats cannot leave the premises,” DeYoung and Schouten said.
Compulsory screening of all mink farms in the Netherlands for the presence of COVID-19 is now underway, DeYoung and Schouten assured the Dutch parliament, while veterinary epidemiological research continues at the three mink farms where COVID-19 was first detected continues, chiefly to see whether herd immunity develops among the mink, or whether they will continue to shed virus potentially capable of infecting each other, humans, and other species.
The DeYoung and Schouten disclosures came six days after on May 19, 2020 acknowledged to the Dutch parliament that “It is plausible that an employee of one of the infected mink companies was infected with SARS-CoV-2 [COVID-19] by the minks.
“This employee has since recovered,” Schouten said then, 11 days after the infection of the mink was confirmed.
Finding calls COVID-19 containment strategy into question
The mere fact that a human had apparently caught COVID-19 from mink called into question the entire global strategy for combatting the spread of the disease, which has so far focused on interrupting human-to-human transmission––and called into question also the prevailing theories about how COVID-19 first passed to humans in November 2019 in Wuhuan, China.
That human COVID-19 carriers can infect other animal species was already known from scattered cases in Hong Kong, several European nations, and the U.S. in which humans apparently infected cats, dogs, and even tigers at the Bronx Zoo.
Some of the Bronx Zoo tigers are believed to have passed COVID-19 on to others of their own species who were housed with them.
None of the animals in the previously known instances of human-to-animal transmission, however, passed COVID-19 back to humans.
The Dutch mink did, thereby demonstrating, Schouten told the parliamentarians, that “Minks can experience COVID-19 without displaying symptoms.”
Can other species become COVID-19 carriers?
If mink can become immune carriers of COVID-19, perhaps other animals can––to much more dangerous effect.
The evolutionary distance from mink to Norway and black rats, for instance, is a mere fraction of the evolutionary distance from humans to mink, meaning that COVID-19 might have to mutate much less to infect rats than to pass from human to mink back to human.
Yet the chance that COVID-19 might infect rats or most other animal species is considered relatively unlikely.
Mink, relatively uniquely, share with humans “a protein on their lungs, the ACE2 receptor, to which the virus likes to attach itself,” explained the Wageningen University report that confirmed the infection in mink.
“Humans also have this coronavirus binder on the mucous membranes of their mouths,” the Wageningen report continued. “This protein appears to be a good predictor for possible infection with COVID-19.”
Cats, ferrets, & pigs
Rats and mice, unless transgenically modified, lack enough of the ACE2 receptor protein in vulnerable places to make them likely COVID-19 carriers.
But cats, ferrets, and pigs are considered potential COVID-19 carriers, along with a large array of wildlife whose likelihood of becoming carriers has yet to be explored.
African swine fever has cut Chinese pig production from more than 400 million at peak to 275 million expected in 2020, but China still has more pigs than any two other nations.
Most of the previous cases of human-to-animal COVID-19 transmission, the tiger cases excepted, involved intensive contact between humans known to have been infected and animals who eventually exhibited symptoms.
Factory-farmed pigs, and mink ranched for fur pelts, however, are raised with minimal direct human contact. COVID-19 has not yet actually been found in pigs, while “Only a few mink showed symptoms of the disease,” the Wageningen University bioveterinary research laboratory found when confirming the infections on the three Dutch farms.
“The mink are kept in separate pens,” the Wageningen University report continued, “which means that there is little to no contact among the animals.”
Were mink intermediaries in bats-to-humans jump?
Nonetheless, Schouten said then, “It is unlikely that only human-to-mink transmission has taken place on the farms. The characteristics of the virus indicate transmission between minks.”
Schouten noted to the Dutch parliament then that free-roaming cats might have wandered among the mink forms in the closely clustered villages of Milheeze, De Mortel [a suburb of Gemert-Bakel], and Deurne, in the corner of the Netherlands bordering on both Belgium and Germany, where the interspecies COVID-19 infections occurred.
The finding that both ranched mink and free-roaming cats are vulnerable to COVID-19 hints that either mink or cats might be potential COVID-19 carriers too, and might therefore have had a role in the disease making the jump from bats to humans.
Cats in Wuhan
Some western media reported that mink were sold for human consumption at the Huanan Seafood Wholesale Market in Wuhan, China, where the global COVID-19 pandemic is believed to have begun, but Chinese media have reported that mink are inedible.
Cats may also have been sold for human consumption at the Huanan Seafood Wholesale Market, though Wuhan is 664 miles north of Guangzhou, the only city in China where cats have historically often been eaten.
But the 15-year-old Huanan Seafood Wholesale Market is chiefly a fish market, and fish markets have attracted free-roaming cats to eat scraps and leftovers for as long as records and artistic depictions of fish markets have existed: about 7,000 years, from the first documentation of feline domestication in ancient Egypt times to now.
Not from a laboratory
Despite overwhelming scientific agreement that COVID-19 somehow passed from bats to humans through an intermediary species sold or otherwise present at the Huanan Seafood Wholesale Market, U.S. president Donald Trump and many of his followers continue to amplify claims, offered with no supporting evidence, that it might instead have escaped from the Wuhan Institute of Virology.
Responded Wuhan Institute of Virology director Wang Yanyi through state media on May 24, 2020, “We never had any knowledge of COVID-19 before the outbreak, nor had we ever met, researched or kept the virus. We didn’t even know about the existence of the virus, so how could it be leaked from our lab when we didn’t have it?”
The Wuhan Institute of Virology was instrumental in identifying COVID-19 as a novel virus, previously unknown to science, when a series of severe “atypical pneumonia” cases stumped Wuhan medical doctors, in warning the world about it on December 30, 2019, and in genetically sequencing it, then sharing the genetic code with scientists worldwide a few days later.
Wuhan bans wildlife consumption
As of May 20, 2020, Wuhan “has banned the eating of wild animals and Chinese farmers are being offered cash to quit breeding exotic animals,” Agence France Presse reported.
“The city also banned virtually all hunting of wild animals within its limits, declaring Wuhan a wildlife sanctuary,” Agence France Presse continued, “with the exception of government sanctioned hunting for ‘scientific research, population regulation, monitoring of epidemic diseases and other special circumstances.’
“Wuhan also imposed strict new controls on the breeding of all wild animals, making clear that none could be reared as food,” Agence France Presse added. “City officials said the local administration would take part in a wider national scheme to buy wild animal breeders out of business.”
The Beijing-based Chinese national government “had already banned the sale of wild animals for food as the coronavirus spread around the world,” Agence France Presse summarized, “citing the risk of diseases spreading to humans, but the trade remains legal for other purposes — including research and traditional medicine.”
Farmers to be bought out of wildlife breeding
Meanwhile, Hunan and Jiangxi provinces, both bordering Hubei, of which Wuhan is the capital city, “have already outlined details of a buyout program to help farmers switch to alternative livelihoods,” Agence France Presse explained, including payments of about $8.00 per pound for rat snakes, king ratsnakes and cobra, about $5.25 per pound for bamboo rats, and $42 per pound for civets, the species believed to have been the intermediary between bats and humans in spreading Severe Acute Respiratory Syndrome (SARS) in 2003.
Peter Li, China policy advisor for the Humane Society International subsidiary of the Humane Society of the U.S., praised the buyout program and argued that it should be expanded to all of China, as rapidly as possible, as well as to breeding wildlife for medicinal use, use in entertainment, and as exotic pets.
The Beijing agriculture ministry in April 2020 published a draft reclassification of regulated animal species which would remove dogs from the “livestock” category, a big step toward ending dog-eating, leaving 18 other species recognized as livestock, including cattle, pigs, poultry, and camels.
Species raised for fur exempted
Another 13 “special” species would also be exempted from wild animal trading restrictions, including reindeer, alpaca, pheasants, and ostriches, along with three species traditionally raised for fur: mink, fox, and tanuki (“raccoon dogs”).
Chinese fur farms reportedly pelted more than 40 million mink in 2015, but as global fur demand and prices collapsed during the next several years, Chinese mink output has reportedly fallen to about seven million pelts per year––barely more than the six million pelts produced in recent years by the 140 mink farms remaining in the Netherlands, down from about 160 farms in 2015.
The Netherlands remains the fourth largest mink pelt producing nation, albeit far behind Denmark and Russia. The U.S. is a distant fifth, but will move up to fourth when an 11-year phase-out of the Dutch mink industry, approved by the Dutch parliament in 2013, is completed in 2024.