Tuesday, May 26, 2020

COVID-19: Back To The Mink Farm


Not quite a month ago, in Netherlands: COVID-19 In Farmed Mink, we looked at preliminary reports released by the Netherlands' National Institute for Public Health - RIVM, on the detection of SARS-CoV-2 at two mink farms - located roughly 5 km apart - in the south-central part of the country.
While this was the first confirmed SARS-CoV-2 infection reported in mink, it was hardly surprising. 
Nearly two months ago, in Susceptibility of Ferrets, Cats, Dogs & Other Domestic Animals to SARS-CoV-2, we looked at the experimental infection of a variety of farmed animals and household pets with the novel coronavirus. The authors wrote:
We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but efficiently in ferrets and cats. We found that the virus transmits in cats via respiratory droplets.
Mink are quite similar to ferrets - both being members of the Mustela genus - and have a long history of being susceptible to a variety of novel flu and respiratory viruses (see below). 
Nature: Semiaquatic Mammals As Intermediate Hosts For Avian Influenza
That Touch Of Mink Flu (H9N2 Edition)
Vet. MicroB.: Eurasian Avian-Like Swine Influenza A (H1N1) Virus from Mink in China
Over the past few days the Netherlands have reported additional mink farms affected by the pandemic virus, including a spillover into cats, and possibly even some mink-to-human transmission. The following (translated) report comes from Wageningen Bioveterinary Research (WBVR).
COVID-19 detected at four mink farms
Published on May 26, 2020
On April 26, two mink companies in Gemert-Bakel and Laarbeek detected infections of COVID-19 in different minks. On May 7, two other mink companies in De Mortel and Deurne were found to be contaminated. The minks showed various symptoms including respiratory problems and increased mortality. Some employees at both companies had symptoms of the coronavirus. Research shows that mink on the farm have transmitted the virus to each other. Furthermore, it is plausible that two contaminations have occurred from mink to human.

The Animal Health Service (GD), Utrecht University (UU) and Erasmus MC and Wageningen Bioveterinary Research (WBVR) are conducting research to gain more insight into the virus, the spread of the virus and the spread in the environment. Samples of sick and healthy animals have been collected and air and dust samples have also been taken in the vicinity of the farms as a precaution. GGD is involved in sampling and research into contamination of employees.
Virus transferred between minks
Previous research shows that ferrets, and therefore also minks, are susceptible to COVID-19 contamination. Pneumonia was seen in sections on animals 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.
Possible contamination from animal to human
Minister Schouten of Agriculture, Nature and Food Quality (LNV) reports in a letter to parliament dated 19 May that it is plausible that a coronavirus infection has occurred from mink to man. In a letter to parliament dated 25 May , the minister reports that there is very likely a second infection.
The minister has announced additional measures for mink farms. All companies are screened and visitors are banned from visiting the stables. A reporting obligation had already been introduced and employees were already required to wear protective clothing.
Virus in dust particles in the stables
Virus RNA has been detected in dust particles in the stables, indicating that people in the stables with infected mink can be exposed to coronavirus.
No virus in the air samples outside the house
In the letter to parliament of 8 May from Minister Schouten of LNV to the House of Representatives, it appears that the initial results of the investigation show that no virus was found in the air samples outside the house. RIVM indicates that the risk of exposure of people to the virus outside the house is negligible.
Area precaution is no longer required
In the second sampling series, the virus was no longer found inside or outside the house in the dust particles in the air. Minister Schouten announced this in the letter to parliament of 15 May . The previous RIVM advice not to walk or cycle in a 400-meter zone around an infected mink farm has therefore been withdrawn.
Three cats infected
The study also tested eleven cats at one of the infected business locations. Antibodies to COVID-19 have been demonstrated in three of these cats. That means the cats have been infected.
Ut is important to further investigate the role of cats in potential virus transmission of this respiratory infection. In this context, research into, among other things, (virus) transmission in cats is carried out by the Netherlands Center for One Health partnership . It unites: Faculty of Veterinary Medicine at Utrecht University, Wageningen Bioveterinary Research, Erasmus University Rotterdam and research centers in human health care.
WBVR tested the animals
Wageningen Bioveterinary Research (WBVR) has performed confirmation tests on samples from the mink. In addition, further research is being started in collaboration with GD, UU and EMC.

In a (translated) Letter to parliament  (May 25th) on developments in COVID-19 on mink farms, Ministers De Jonge and Schouten summarize the most recent developments and research results concerning COVID-19 on mink farms.
In our letter of May 19, we reported that there are three farm cats on it an infected mink farm tested positive for serological testing. On this further investigation has taken place. In total, seven of the 24 sampled farm cats tested positive at a serological site research. That is, these positive cats have antibodies created against the virus.
One of the positive cats was under investigation virus detected, however the amount of virus detected is probably too little to unravel the genetic code. The other six cats could no virus can be detected. That means these last six cats have a CoV 2 have gone through infection and no longer shed virus. Because cats being infected with CoV-2 has been previously known to infected mink farms advised to ensure that their cats cannot enter the company premises leave. 
Farmed Mink being susceptible to SARS-CoV-2 poses far less of a concern than if the virus had an affinity for pigs or poultry - but it is important to monitor other potential hosts for the virus - as they could provide additional opportunities for the virus to adapt and evolve outside of our view.

As far as felines are concerned, over the past couple of months we've looked at a number of field reports, and some limited research, on the susceptibility of cats to the COVID-19 pandemic and their potential for transmitting the SARS-CoV-2 virus to others.
CDC: Pets & Other Animals and COVID-19
NEJM: Transmission of SARS-CoV-2 in Domestic Cats
APHIS: Confirmation of COVID-19 in Two Pet Cats in New York
The evidence thus far suggests your cat is far more likely to contract the SARS-CoV-2 virus from you, or another human, than to spread it to humans   What is known as Reverse Zoonosis. 

We are, of course, still learning about this pandemic virus. For those looking for more information, the AVMA (American Veterinary Medical Association) maintains a detailed webpage (updated May 15th) on what is currently known about animal infection with the SARS-CoV-2 virus.

While the infection risk to, and from, animals is believed to be low at this time, the AVMA recommends the following precautions:

Despite the number of global cases of COVID-19 surpassing the 4 million mark as of May 9, 2020, we are aware of only a handful of pets and captive or farmed wild animals that have tested positive for SARS-CoV-2. In all cases, the source of the infection for these animals was presumed to be one or more persons with confirmed or suspected COVID-19. At this point in time, there is also no evidence that domestic animals, including pets and livestock, can spread COVID-19 to people. 
Therefore, the AVMA maintains its current recommendations regarding SARS-CoV-2 and animals. These recommendations, which are supported by guidance from the US Centers for Disease Control and Prevention (CDC) and World Organization for Animal Health (OIE), are that:
  • Animal owners without symptoms of COVID-19 should continue to practice good hygiene during interactions with animals. This includes washing hands before and after such interactions and when handling animal food, waste, or supplies.
  • Do not let pets interact with people or other animals outside the household.
  • Keep cats indoors, when possible, to prevent them from interacting with other animals or people.
  • Walk dogs on a leash, maintaining at least 6 feet from other people and animals. Avoid dog parks or public places where a large number of people and dogs gather.
  • Until more is known about the virus, those ill with COVID-19 should restrict contact with pets and other animals, just as you would restrict your contact with other people. Have another member of your household or business take care of feeding and otherwise caring for any animals, including pets. If you have a service animal or you must care for your animals, including pets, then wear a cloth face covering; don’t share food, kiss, or hug them, and wash your hands before and after any contact with them.
  • At this point in time, there is no evidence to suggest that domestic animals, including pets and livestock, that may be incidentally infected by humans play a role in the spread of COVID-19.
  • Routine testing of animals for SARS-CoV-2 is NOT recommended. Veterinarians are strongly encouraged to rule out other, more common causes of illness in animals before considering testing for SARS-CoV-2.
  • Human outbreaks are driven by person-to-person transmission. Accordingly, we see no reason to remove pets from homes even if COVID-19 has been identified in members of the household, unless there is risk that the pet itself is not able to be cared for appropriately.
During this pandemic emergency, animals and people each need the support of the other and veterinarians are there to support the good health of both.