Questions and answers regarding infection with COVID-19 in mink

From the end of April, mink have tested positive with COVID-19 at dozens of mink farms in the Netherlands. It is also likely that mink have transmitted the virus to employees. Wageningen Bioveterinary Research (WBVR) tested the animals positive for the coronavirus (SARS-CoV-2). Other animals, such as cats, may also be susceptible to this virus.

Below are frequently asked questions and answers about coronavirus in mink in the Netherlands, the research currently being conducted and coronavirus in other kept animals.

Subjects:

  1. Symptoms of the disease and the infection of mink
  2. Research on coronavirus in mink
  3. Is there any danger to the environment?
  4. Mutation of the coronavirus in mink (in Denmark)
  5. Other animals and coronavirus
  6. Handling my animals

1. Symptoms of the disease and the infection of mink

How did the mink become infected?

Some employees at the mink farms have had symptoms of COVID-19. It appears that the virus was introduced to the mink via these employees.

Mink are very susceptible to the virus circulating in humans. So when infected people get in contact with mink they can very easily infect them.

How many mink were infected?

The virus was detected from the end of April. Since the manditory screening of all Dutch mink farms from 25 May, dozens more farms have been added to that list. Read the latest update on our news page about infected mink farms.

A few mink showed symptoms of the disease on the farms. The mink are kept in separate pens, which means that there is little to no contact between the animals.

What symptoms did the mink display?

The infected mink suffered from gastrointestinal complaints and respiratory problems. The mortality rate at the affected farms was also higher than usual. There is a fatality rate between 1 and 5% (this is not extremely high).

Research from Wageningen Bioveterinary Research shows that the mink died of severe pneumonia.

Was it already known that mink are sensitive to coronavirus?

Mustelids such as mink are extra sensitive to coronavirus. Like humans, they have a protein on their lungs, the ACE2 receptor, to which the virus likes to attach itself. Humans also have this ‘coronavirus binder’ on the mucous membranes of their mouths, for example. This protein appears to be a good predictor for possible infection with COVID-19.

How was coronavirus diagnosed in mink?

The mink symptoms prompted the veterinarians to have an investigation carried out by the Animal Health Service. Since the animals tested negative for the most obvious bacterial diseases, GD Animal Health also tested for coronavirus (SARS-CoV-2) due to the alleged susceptibility of mink to infection and because individuals with COVID-19 symptoms were working on both farms. The PCR test showed an infection with coronavirus. A similar test at Wageningen Bioveterinary Research (WBVR) confirmed this result.

What are the consequences for mink farms?

Mink farmers are now obliged to report symptoms of COVID-19 (respiratory problems and increased mortality) to the national animal disease reporting centre of the Netherlands Food and Consumer Product Safety Authority (NVWA).

Additional protection recommendations have been drawn up for mink farms where contamination with SARS-CoV-2 has been established.

No transport

The Dutch Ministry of Agriculture, Nature and Food Quality (LNV) has decided that mink and their manure are no longer allowed to be transported. The risks presented by the manure seem small but will be investigated further. On 10 July, LNV adjusted the regulations. Manure from infected mink farms may only be transported to biogas plants where it is heated to at least 70˚C.

Screening of all mink farms

It is likely that the virus has been transmitted from mink to employees. All Dutch mink farms will be screened and visitors are banned from visiting the stables.

Culling of the infected farms from 5 June

The Dutch government announced that the mink farms infected with COVID-19 will be culled from Friday 5 June. The government took this decision on the basis of the advice of the Outbreak Management Team for Zoonoses and the Administrative Coordination Consultation for Zoonoses. The advice to cull was given because the virus can continue to circulate on mink farms for a long time and can therefore pose a risk to public and animal health.

Closing scheme from spring 2021

Based on the studies carried out and the advice of the Outbreak Management Team Zoönosen (OMT-Z), the Dutch cabinet has decided to introduce a mandatory stopping scheme for all mink farms in the Netherlands per 21 March 2021. Infected farms are culled and at all other mink farms an even more stringent control is being instituted, so that any new infections are discovered quickly. This is stated in a letter to Parliament of 28 August.

Can mink transmit the virus to each other? (via inhalation)

Dutch researchers have shown that ferrets can infect each other via inhalation. Since mink are closely related to ferrets, it is possible that they can also transmit the virus to each other.

Pneumonia was seen in sections on mink and SARS-CoV-2 was detected in organs and throat swabs. Based on the variations in the genetic codes of the virus, it could be concluded that mink farms have transmitted the virus to each other.

Mink are very susceptible and they are housed with large numbers in relatively small areas. In most farms all the cages are next to each other with a closed wall in-between, but the tops are open. So when the animals cough or sneeze – like mink do – they can easily spread the virus from one top of the cage to the other top of the cage.

Can mink transmit the virus to humans?

It is plausible that employees were infected with the coronavirus by mink. The Dutch government stated this on May 19 and 25.

Further investigation of the increasing number of infected mink farms has shown that many of the employees surveyed were infected with coronavirus (more than 50 percent). Based on the genetic building blocks of the virus, it was possible to establish for some of these employees that this virus was similar to the virus that circulated among the minks on the farm. On this basis, it can be concluded that many of these people are very likely to be directly or indirectly infected by the mink.

Are further infections on mink farms expected?

There are approximately 130 fur farms in the Netherlands. Now that mink appear to be susceptible to the virus, there is a chance that the virus will be found on more farms. Mink farmers are obliged to report this to the Netherlands Food and Consumer Product Safety Authority.

All Dutch mink farms are screened and visitors are banned from visiting the stables. Infected farms are culled as of June 5.

During this screening on more farms in the Netherlands COVID-19 infected mink have been found.

A letter to Parliament dated 28 August states that an even more stringent control is being instituted for all Dutch mink farms. And a mandatory closing scheme for mink farms in the Netherlands is introduced from the spring of 2021.

Besides the infections found in the mink farms there are currently no known cases where coronavirus has been detected in farm animals.

2. Research on coronavirus in mink

What is being researched at these farms?

Research is being conducted into the source of the infection and the transmission of the virus. It is important to know how the disease develops on the farm, as this provides knowledge about COVID-19 in animals and the transmission from human to animal and animal to animal.

Samples from sick animals are collected on the farms for testing. Samples from healthy animals are also collected for antibodies, so that it becomes clear whether animals without symptoms can also be infected. The research is a collaboration between Utrecht University (UU), GD Animal Health, Erasmus MC and Wageningen Bioveterinary Research (WBVR).

Furthermore, dogs and cats on the infected farms are included in the study. Infections were found in cats on the first six farms. The virus was not found in any of the dogs examined. It does not seem very likely that cats play a role in spreading the virus. But given the many households with cats in the Netherlands, it is important to further investigate the role of cats in the potential virus transmission of this respiratory infection.

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