Coronavirus rips through Dutch mink farms, triggering culls to prevent human infections
www.sciencemag.org
...In a sad sideshow to the COVID-19 pandemic, authorities in the Netherlands began to gas tens of thousands of mink on 6 June, most of them pups born only weeks ago. SARS-CoV-2 has attacked farms that raise the animals for fur, and the Dutch government worries infected mink could become a viral reservoir that could cause new outbreaks in humans.
The mink outbreaks are "spillover" from the human pandemic"a zoonosis in reverse that has offered scientists in the Netherlands a unique chance to study how the virus jumps between species and burns through large animal populations.
But they're also a public health problem. Genetic and epidemiological sleuthing has shown that at least two farm workers have caught the virus from mink"the only patients anywhere known to have become infected by animals. SARS-CoV-2 can infect other animals, including cats, dogs, tigers, hamsters, ferrets, and macaques, but there are no known cases of transmission from these species back into the human population. (The virus originally spread to humans from an as-yet-unidentified animal species.)...
The Dutch outbreaks are giving scientists a chance to study how the virus adapts as it spreads through a large, dense population. In some other animal viruses, such conditions trigger an evolution toward a more virulent form, because the virus isn't penalized if it kills a host animal quickly as long as it can easily jump to the next one. (Avian influenza, for instance, usually spreads as a mild disease in wild birds but can become highly pathogenic when it lands in a poultry barn.) Although SARS-CoV-2 is undergoing plenty of mutations as it spreads through mink, its virulence shows no signs of increasing.
Even so, the Dutch outbreaks have alarmed people in North Brabant province, where mink farms are concentrated. The region's burgeoning goat industry caused the world's largest human epidemic of Q fever between 2007 and 2009. Anxious citizens feared a repeat with SARS-CoV-2 and mink. But Coxiella burnetii, the bacterium that causes Q fever, forms hardy spores that wafted out of barns and blew off fields fertilized with goat manure. SARS-CoV-2 is far more fragile; environmental sampling has not turned up any virus outside mink sheds, says veterinary epidemiologist Arjan Stegeman of Utrecht University, who leads the research on mink outbreaks. Whereas farm workers should wear protective equipment, the population at large is at very low risk, Stegeman says....
