At least 66 employees and family members have been infected during outbreaks on mink farms. That is 68% of the total number of people tested on the farms, according to an extensive Dutch study of the outbreak on sixteen farms. The total number of infections on farms may be much higher, because at least 50 of the 128 mink farms in the Netherlands are infected
Certainly in a number of cases the virus has been transmitted from mink to humans. The outbreak on mink farms is therefore more serious than expected. In the first instance, Minister Schouten (Agriculture) did not estimate the risk of contagion from mink to humans.
The study was published on a life sciences website at the beginning of this month. Scientists suspect that the virus had been circulating in mink populations for some time before spreading to humans. The virus also mutated widely among minks, on average once every fortnight.
Cat possible cause
Scientists have no direct explanation for the fact that the virus passed from breeding to breeding in May and June, when the outbreak was contained nationwide. They mention infected breeding visitors or wild cats as possible causes.
The Dutch Food and Consumer Product Safety Authority has also started an investigation into possible deliberate contamination
Missing link spread
The investigation has virtually established that minks can be classified as a reservoir for the virus. Virologist and research leader Marion Koopmans of Erasmus MC says to de Volkskrant that the fur industry may well be the “missing link” that contributed to the switch from animal to human in China. “This could be a plausible intermediate step in the path the virus has taken from bats to humans,” she says.
Because of the outbreaks on the farms, all breeding farms in the Netherlands will have to stop in March next year. The ‘fur period’ starts in November and once all minks have been killed and their fur removed, the breeders are no longer allowed to put new animals in their cages.