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Between September and January this year, mink from 3 Polish farms tested positive for the pandemic coronavirus, SARS-CoV-2, presenting a disturbing mystery about how the animals became infected.
But recent cases in the Polish mink, reported this week in the journal Eurosurveillance, are unusual. While previous mink outbreaks have been linked to inflamed farm staff and local flow of the virus, indicating human-to-mink spread, none of the farm’s mink. Staff or families on recently affected farms have tested positive for the virus. In fact, fitness researchers found that the inflamed mink carried a strain of SARS-CoV-2 that has been observed in humans in the domain for more than two years (B. 1. 1. 307).
The location suggests that humans were not guilty of infecting mink, at least not directly. Rather, it suggests that some other unknown species might have quietly harbored and propagated the otherwise passed strain for some time and controlled to send it to minks. Farms
The suggestion raises more considerations about the viral flashback. The term refers to the maximum “spillover” identified, when a virus moves from a host population, a reservoir, to a new population, such as humans. SARS-CoV-2 is thought to have originated in a reservoir of horseshoe bats before reaching humans. Since then, it has been transparent that it can also infect a wide diversity of animals, adding rodents, cats, dogs, white-tailed deer, non-human primates, as well as ferrets and minks. Researchers worry that the virus could spread to an animal population that could be just a new reservoir from which the virus can periodically return to humans.
This concern attracted attention when the omicron variant gave the impression with its strangely broad series of genetic changes. Some researchers have hypothesized that omicron possibly spread cryptically and evolved in mice before re-infecting humans. Other researchers, however, hypothesize that the variant evolved in an immunocompromised person.
Farmed mink in Poland highlights the threat of backtracking by suggesting an unknown reservoir of SARS-CoV-2 in wild animals. In one research, researchers from the National Institute of Veterinary Research and Erasmus University Medical Center tested instances on 3 farms within 8 km (about five miles) of another. The first farm reported two inflamed minks (out of 1five tested and about 8,600 animals in total) on September 19, but they later tested negative and were skinned as expected. On November 16, a 4,000 mink farm reported that six out of five inflamed animals were examined and carefully skinned. The third farm, with 1100 mink, discovered five of five inflamed animals tested on Jan. 18, but then tested negative in two rounds of testing in five days. All inflamed animals on the 3 farms were asymptomatic.
The researchers received 8 complete genome sequences, 4 each from the moment and 3 from the farm; There was not enough germplasm in the samples from the first farm. The genome sequences showed that they were almost the same and very similar to lineage B. 1. 1. 307, which had not been observed in humans in Poland for more than two years. The viruses also had 40 small genetic mutations, some of which have already been linked to flow in mink, and may have been acquired quickly. None of the farming families or staff tested positive for SARS-CoV-2 on any of the 3 farms.
The researchers noted that the 3 beams had concrete fences 1. 8 meters (6 feet) high and between 30 and 40 cm (about a foot) deep. created a Directorate for Wildlife. Interviews with owners and staff revealed that the farms were visited by wild martens, weasel-like carnivores. And there were also wild cats around. The researchers analyzed feces from feral cats on farms, but found that they were negative for SARS-CoV-2.
The researchers concluded that a wild animal (martens, feral cats or even escaped mink) may have cryptically spread the SARS-CoV-2 lineage and carried it to the three nearby farms on separate occasions. They called for more surveillance, not only on mink farms, but also on populations of wild animals, such as martens, ferrets and foxes.
“Animals from SARS-CoV-2-positive mink farms showed no symptoms of the disease, creating an independent viral evolution option and possibly a source of long-term outbreaks with new strains,” they wrote.
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