Transmission of SARS-CoV-2 on mink farms between humans and mink and back to humans
Bas B. Oude Munnink1 *, Reina S. Sikkema1 , David F. Nieuwenhuijse1 , Robert Jan Molenaar2, Emmanuelle Munger1 , Richard Molenkamp1 , Arco van der Spek3, Paulien Tolsma4, Ariene Rietveld5, Miranda Brouwer5 , Noortje Bouwmeester-Vincken6, Frank Harders7 , Renate Hakze-van der Honing7 , Marjolein C. A. WegdamBlans8, Ruth J. Bouwstra2, Corine GeurtsvanKessel1 , Annemiek A. van der Eijk1 , Francisca C. Velkers9, Lidwien A. M. Smit10, Arjan Stegeman9, Wim H. M. van der Poel7 , Marion P. G. Koopmans1 1 Erasmus MC, Department of Viroscience, WHO collaborating centre for arbovirus and viral hemorrhagic fever Reference and Research, Rotterdam, Netherlands. 2Royal GD, Deventer, Netherlands. 3 Netherlands Food and Consumer Product Safety Authority (NVWA), Utrecht, Netherlands. 4Municipal health Services GGD Brabant-Zuidoost, Eindhoven, Netherlands. 5 Municipal health Services GGD Hart voor Brabant, ‘s-Hertogenbosch, Netherlands. 6Municipal health Services GGD Limburg-Noord, Venlo, Netherlands. 7 Wageningen Bioveterinary Research, Lelystad, Netherlands. 8Stichting PAMM, Veldhoven, Netherlands. 9Farm Animal Health, Utrecht University, Utrecht, Netherlands. 10Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, Netherlands.
*Corresponding author: Email: b.oudemunnink@erasmusmc.nl
Animal experiments have shown that non-human primates, cats, ferrets, hamsters, rabbits and bats can be infected by SARS-CoV-2. In addition, SARS-CoV-2 RNA has been detected in felids, mink and dogs in the field. Here, we describe an in-depth investigation using whole genome sequencing of outbreaks on 16 mink farms and the humans living or working on these farms. We conclude that the virus was initially introduced from humans and has since evolved, most likely reflecting widespread circulation among mink in the beginning of the infection period several weeks prior to detection. Despite enhanced biosecurity, early warning surveillance and immediate culling of infected farms, transmission occurred between mink farms in three big transmission clusters with unknown modes of transmission. Sixty-eight percent (68%) of the tested mink farm residents, employees and/or contacts had evidence of SARS-CoV-2 infection. Where whole genomes were available, these persons were infected with strains with an animal sequence signature, providing evidence of animal to human transmission of SARS-CoV-2 within mink farms.
Late December 2019, SARS-CoV-2 was identified as causing in a viral pneumonia outbreak, possibly related to a seafood and a live animal market in Wuhan, China (1). Since then, SARS-CoV-2 spread across the world and by October 8 2020, over 36,100,000 people had been infected with SARS-CoV-2 resulting in over 1,000,000 deaths (2). In the Netherlands, over 155,000 infections have been confirmed, over 6,500 SARS-CoV-2 related deaths have been reported, and nonpharmaceutical interventions have been put into place to prevent further spread of SARS-CoV-2 (3).
In view of the similarities of the new virus with SARSCoV-1, a zoonotic origin of the outbreak was suspected linked to the Wuhan fresh market where various animals were sold including fish, shellfish, poultry, wild birds and exotic animals. The finding of cases with onset of illness well before the period observed in the Wuhan market-associated cluster suggests the possibility of other sources (4). Although closely related coronaviruses found in bats (5, 6) and pangolins (7, 8) have greatest sequence identity to SARS-CoV-2, the most likely divergence of SARS-CoV-2 from the most closely related bat sequence is estimated somewhere between 1948-1982 (9). Therefore, the animal reservoir(s) of SARS-CoV-2 is (are) yet to be identified.
Similar to SARS-CoV-1, SARS-CoV-2 binds to the host angiotensin-converting enzyme 2 (ACE2) receptor. Based on ACE2 similarities, a range of different animals have been used as models. Experimental infections in dogs (10), cats (10–13), ferrets (10, 14), hamsters (15, 16), rhesus macaques (17), tree shrew (18), cynomolgus macaques (19), African green monkey (20), common marmosets (21), rabbits (22), and fruit bats (23) have shown that these species are susceptible to SARS-CoV-2, and experimentally infected cats, tree shrews, hamsters and ferrets could also transmit the virus. In contrast, experimental infection of pigs and several poultry species with SARS-CoV-2 proved to be unsuccessful (10, 23, 24). SARS-CoV-2 has also sporadically been identified in naturally infected animals. In the USA and in Hong Kong, SARSCoV-2 RNA has been detected in dogs (25). In the Netherlands, France, Hong Kong, Belgium, Spain and the USA, cats have tested positive by RT-PCR for SARS-CoV-2 (26–30). Furthermore, SARS-CoV-2 has been detected in four tigers and three lions in a zoo in New York (31). In Italy, the Netherlands and in Wuhan, antibodies to SARS-CoV-2 have been detected in cats (29, 32, 33). Recently, SARS-CoV-2 was detected in farmed mink (Neovison vison) resulting in signs of respiratory disease and increased mortality (29, 34).
In response to the outbreaks in mink farms, the Dutch national response system for zoonotic diseases was activated, and it was concluded that the public health risk of exposure to animals with SARS-CoV-2 was low, but that there was a need for increased awareness of possible involvement of animals in the COVID-19 epidemic. Therefore, from May 20th 2020 onwards, mink farmers, veterinarians and laboratories were obliged to report symptoms in mink (family Mustelidae) to the Netherlands Food and Consumer Product Safety Authority (NFCPSA) and an extensive surveillance system was set up (35).
Whole genome sequencing (WGS) can be used to monitor the emergence and spread of pathogens (36–39). As part of the surveillance effort in the Netherlands over 1,750 SARSCoV-2 viruses have been sequenced to date from patients from different parts of the Netherlands (40). Here, we describe an in-depth investigation into the SARS-CoV-2 outbreak in mink farms and mink farm employees in the Netherlands, combining epidemiological information, surveillance data and WGS on the human-animal interface. SARS-CoV-2 was first diagnosed on two mink farms in the Netherlands on April 23rd (NB1) and April 25th (NB2), respectively. After the initial detection of SARS-CoV-2 on these farms an in-depth investigation was initiated to identify potential transmission routes and to perform an environmental and occupational risk assessment. Here, we describe the results of the outbreak investigation of the first 16 SARS-CoV-2 infected mink farms by combining SARS-CoV-2 diagnostics, WGS and in-depth interviews.
Owners and employees of the 16 SARS-CoV-2 positive mink farms were included in the contact tracing investigation of the municipal health services and tested according to national protocol. In total, 97 individuals were tested by either serological assays and/or RT-PCR. In total, 43 out of 88 (49%) upper-respiratory tract samples tested positive by RTPCR while 38 out of 75 (51%) serum samples tested positive for SARS-CoV-2 specific antibodies. In total, 66 of 97 (68%) of the persons tested had evidence for SARS-CoV-2 infection (Table 1).
During the interview on April 28th, four of five employees from NB1 reported that they had experienced respiratory symptoms before the outbreak was detected in minks, but none of them had been tested for SARS-CoV-2. The first dates of their symptoms ranged from April 1st to May 9th. For 16 of the mink, sampled on April 28th, and one farm employee, sampled on May 4th, a WGS was obtained (hCov-19/Netherlands/NoordBrabant_177/2020). The human sequence clusters within the mink sequences although it displayed 7 nucleotides difference with the closest mink sequence (Fig. 1 and cluster A in Figs. 2 and 3). On farm NB2, SARS-CoV-2 was diagnosed on April 25th. Retrospective analysis showed that one employee from NB2 had been hospitalized with SARS-CoV-2 on March 31st. All samples from the eight employees taken on April 30th were negative by RT-PCR but tested positive for SARS-CoV-2 antibodies. The virus sequence obtained from animals was distinct from that of farm NB1, indicating a separate introduction (Figs. 2 and 3, cluster B).
On mink farm NB3 SARS-CoV-2 infection was diagnosed on May 7th. Initially all seven employees tested negative for SARS-CoV-2, but when retested between May 19th and May 26th after developing COVID-19 related symptoms, five of seven individuals working or living on the farm tested positive for SARS-CoV-2 RNA. WGS were obtained from these five individuals and the clustering of these sequences with the sequences derived from mink from NB3, together with initial negative test result and the start of the symptoms, indicate that the employees were infected with SARS-CoV-2 after mink on the farm became infected. An additional infection was identified from contact-tracing: a close contact of one of the employees who did not visit the farm, became infected with the SARS-CoV-2 strain found in farm NB3. Animal and human sequences from farm NB3 were close to those from farm NB1, and both fell in cluster A.
Similarly, on mink farm NB7 zoonotic transmission from mink to human likely occurred. On this farm, SARS-CoV-2 infection in mink was diagnosed on May 31st and employees initially tested negative for SARS-CoV-2 however, subsequently several NB7 employees began to show symptoms. Samples were taken between June 10th and July 1st from 10 employees of which eight tested positive for SARS-CoV-2 RNA. From two NB7 employee samples, WGS showed their virus sequences clustered with the sequences from the mink at this farm.
The sequences generated from mink farms and from mink farm employees were compared with the national database consisting of around 1,775 WGS. To discriminate between community acquired infections and mink farm related SARSCoV-2 infection, and to determine the potential risk for people living close to mink farms, WGS was also performed on 34 SARS-CoV-2 positive samples, sampled from 04-03-2020 until 29-04-2020, from individuals who live in the same fourdigit postal code area as the first four mink farms. These local sequences, sampled in a proxy of around 19 km2 , reflected the general diversity of SARS-CoV-2 seen in the Netherlands and were not related to the clusters of mink sequences found on the mink farms, thereby indicating no spill-over to people living in close proximity to mink farms had occurred and that the sequences from SARS-CoV-2 infected animals and farm workers clustered by farm (sequences from community shown in magenta, Fig. 2). The sequences from the mink farm investigation were also compared to sequences from Poland (n = 65), since many of the mink farm workers were seasonal migrants from Poland, but these sequences were more divergent.
Phylogenetic analysis of the mink SARS-CoV-2 genomes showed that mink sequences of 16 farms grouped into 5 different clusters (Figs. 2 and 3). Viruses from farms NB1, NB3, NB4, NB8, NB12, NB13 and NB16 belonged to cluster A, sequences from NB2 formed a distinct cluster (B), those from farms NB6, NB7, NB9 and NB14 formed cluster C, NB5, NB8, NB10 and NB15 formed cluster D, and NB11 had sequences designated as cluster E. On farm NB8, SARS-CoV-2 viruses were found from cluster A and cluster D. A detailed inventory of possible common characteristics, including farm owner, shared personnel, feed supplier and veterinary service provider, was made. Multiple farms within a cluster shared the same owner; however, in most cases no common factor could be identified for most farms and clustering could not be explained by geographic distance (Table 2 and Fig. 4). In total 18 sequences from mink farm employees or close contacts were generated from seven different farms. In most cases, these human sequences were near-identical to the mink sequences from the same farm. For NB1 the situation was different and the human sequence clusters deeply within the sequences derived from mink (Fig. 1), with seven nucleotides difference from the closest related mink sequence. This was also the case on farm NB14, with four nucleotides difference from the closest related mink sequence. Employees sampled at mink farm NB8 clustered with animals from NB12, likely because personnel were exchanged between these two farms.
SARS-CoV-2 was detected on mink farm NB1-NB4 after reports of respiratory symptoms and increased mortality in mink. The sequences from farm NB1 showed between 0 and 9 single nucleotide polymorphisms (SNPs) difference (average 3.9 nucleotides) and sequences from NB2 had between 0 and 8 SNPs difference (average of 3.6), which is more than generally observed in outbreaks in human settings. In addition, two deletions, one of 12 and one of 134 nucleotides were observed in single sequence from NB1. The sequences of mink at NB6 had between 0 and 12 SNPs differences and in one sequence a deletion of 9 nucleotides was observed, whereas diversity was lower for the subsequent farm sequences (Table 2). After the initial detection of SARS-CoV-2, farms were screened weekly. The first, second, fifth and sixth weekly screening yielded new positives.
Several non-synonymous mutations were identified among the mink sequences compared to the Wuhan reference sequence NC_045512.2. However, no particular amino acid substitutions were found in all mink samples (fig. S1). Of note, three of the clusters had the position 614G variant (clusters A, C and E), and two had the original variant. There were no obvious differences in the presentation of disease in animals or humans between clusters based on the data available at this stage, but further data collection and analysis also for cases after NB16, are ongoing to investigate this further. The mutations we observed can also be found in the general human population and the same mutations also were found in human cases which were related to the mink farms.
Here we show ongoing SARS-CoV-2 transmission in mink farms and spill-over events to humans. More research in minks and other mustelid species is important to understand if these species are at risk of becoming a reservoir of SARSCoV-2. After the detection of SARS-CoV-2 on mink farms, 68% of the tested farm workers and/or relatives or contacts were to be or have been infected with SARS-CoV-2, indicating that contact with SARS-CoV-2 infected mink is a risk factor for contracting COVID-19. Recently, a 8-fold increase in cytidineto-uridine (C->U) compared to U->C substitutions were described, suggestive of host adaptation (41). In the mink sequences we observed a 3.5-fold increase in C->U compared to U->C substitutions but the number of substitutions was limited (185).
A high diversity in the sequences from some mink farms was observed which is likely explained by multiple generations of viral infections in animals before the increase in mortality was detected. The current estimates are that the substitution rate of SARS-CoV-2 is around 1.16*10^-3 substitutions/site/year in the human population (42), which corresponds to around one mutation per two weeks. This could mean that the virus was already circulating in mink farms for some time. However, there was also a relatively high sequence diversity observed in farms which still tested negative one week prior, hinting toward a faster evolutionary rate of the virus in the mink population. Mink farms have large populations of animals, living at high density, which could promote virus transmission. However, the moment of introduction was not known, making it difficult to draw definite conclusions on the substitution rate in mink farms. Our sequencing did not reveal any systematic mutations that would need to be assessed for potential phenotypic effects. Generation intervals for SARS-CoV-2 in humans have been estimated to be around 4-5 days (43), but with high dose exposure in a farm with a high number and density of animals, this could potentially be shorter.
Further evidence that animals were the most likely source of human infection was provided by the clear phylogenetic separation between mink farm related human and animal sequences and sequences from human cases within the same 4- digit postal code area. However, some of the farm related humans may have been infected within their household, and not directly from mink. Spill-back into the community living in the same 4-digit postal code area was not observed in our sequence data.
So far, the investigation failed to identify common factors that might explain farm-to-farm spread: possibly via temporary workers who were not included in testing. Since our observations, SARS-CoV-2 infections have also been described in mink farms elsewhere (44–46). It is imperative that fur production and trading sector should not become a reservoir for future spillover of SARS-CoV-2 to humans.
REFERENCES AND NOTES
SARS-CoV-2 mink-associated variant strain – Denmark
Disease Outbreak News
6 November 2020
Since June 2020, 214 human cases of COVID-19 have been identified in Denmark with SARS-CoV-2 variants associated with farmed minks, including 12 cases with a unique variant, reported on 5 November. All 12 cases were identified in September 2020 in North Jutland, Denmark. The cases ranged in age from 7 to 79 years, and eight had a link to the mink farming industry and four cases were from the local community.
Initial observations suggest that the clinical presentation, severity and transmission among those infected are similar to that of other circulating SARS-CoV-2 viruses. However, this variant, referred to as the "cluster 5" variant, had a combination of mutations, or changes that have not been previously observed. The implications of the identified changes in this variant are not yet well understood. Preliminary findings indicate that this particular mink-associated variant identified in both minks and the 12 human cases has moderately decreased sensitivity to neutralizing antibodies. Further scientific and laboratory-based studies are required to verify preliminary findings reported and to understand any potential implications of this finding in terms of diagnostics, therapeutics and vaccines in development. In the meantime, actions are being taken by Danish authorities to limit the further spread of this variant of the virus among mink and human populations.
SARS-CoV-2, the virus which causes COVID-19, was first identified in humans in December 2019. As of 6 November, it has affected more than 48 million people causing over 1.2 million deaths worldwide. Although the virus is believed to be ancestrally linked to bats, the virus origin and intermediate host(s) of SARS-CoV-2 have not yet been identified.
Available evidence suggests that the virus is predominantly transmitted between people through respiratory droplets and close contact, but there are also examples of transmission between humans and animals. Several animals that have been in contact with infected humans, such as minks, dogs, domestic cats, lions and tigers, have tested positive for SARS-CoV-2.
Minks were infected following exposure from infected humans. Minks can act as a reservoir of SARS-CoV-2, passing the virus between them, and pose a risk for virus spill-over from mink to humans. People can then transmit this virus within the human population. Additionally, spill-back (human to mink transmission) can occur. It remains a concern when any animal virus spills in to the human population, or when an animal population could contribute to amplifying and spreading a virus affecting humans. As viruses move between human and animal populations, genetic modifications in the virus can occur. These changes can be identified through whole genome sequencing, and when found, experiments can study the possible implications of these changes on the disease in humans.
To date, six countries, namely Denmark, the Netherlands, Spain, Sweden, Italy and the United States of America have reported SARS-CoV-2 in farmed minks to the World Organisation for Animal Health (OIE).
Public health response
Danish authorities have announced the following planned or ongoing public health actions:
Culling of all farmed mink (more than 17 million) in Denmark, including its breeding stock;
Enhancing surveillance of the local population to detect all COVID-19 cases, including through population-wide mass PCR testing for the region of North Jutland;
Expanding the percentage of sequencing of human and mink SARS-CoV-2 infections in Denmark;
Rapid sharing of the full genome sequences of the mink-variant SARS-CoV-2; and Introducing new movement restrictions and other public health measures to affected areas in North Jutland to reduce further transmission, including movement restrictions between municipalities.
WHO risk assessment
All viruses, including SARS-CoV-2, change over time. SARS-CoV-2 strains infecting minks, which are subsequently transmitted to humans, may have acquired unique combinations of mutations. In order to fully understand the impact of specific mutations, advanced laboratory studies are required. These investigations take time and are done in close collaboration between different research groups.
The recent findings reported by the Danish Public Health Authority (Statens Serum Institut) in Denmark related to the novel variant of SARS-CoV-2 identified in humans need to be confirmed and further evaluated to better understand any potential implications in terms of transmission, clinical presentation, diagnostics, therapeutics and vaccine development.
Furthermore, detailed analyses and scientific studies are needed to better understand the reported mutations. The sharing of full genome sequences of human and animal strains will continue to facilitate detailed analyses by partners. Members of the WHO SARS-CoV-2 Virus Evolution Working Group are working with Danish scientists to better understand the available results and collaborate on further studies. Further scientific and laboratory-based studies will be undertaken to understand the implications of these viruses in terms of available SARS-CoV-2 diagnostics, therapeutics and vaccines in development.
Actions taken by the Danish authorities will limit continued spread of mink-associated variants of SARS-CoV-2 in Denmark, and in particular have been implemented to contain the unique variant reported to WHO. These actions include restricting movement of people, culling animals, widespread testing of people living in affected areas and increased genomic sequencing of SARS-CoV-2 viruses across the country.
WHO advice
This event highlights the important role that farmed mink populations can play in the ongoing transmission of SARS-CoV-2 and the critical role of strong surveillance, sampling and sequencing SARS-CoV-2, especially around areas where such animal reservoirs are identified.
The preliminary findings by Denmark are globally relevant and WHO recognises the importance of sharing epidemiological, virological and full genome sequence information with other countries and research teams, including through open-source platforms.
WHO advises further virological studies should be conducted to understand the specific mutations described by Denmark and to further investigate any epidemiological changes in function of the virus in terms of its transmissibility and the severity of disease it causes. WHO advises all countries to increase the sequencing of SARS-CoV-2 viruses where possible and sharing the sequence data internationally.
WHO advises all countries to enhance surveillance for COVID-19 at the animal-human interface where susceptible animal reservoirs are identified, including mink farms.
WHO also reminds countries to strengthen farming biosafety and biosecurity measures around known animal reservoirs in order to limit the risk of zoonotic events associated with SARS-CoV-2. This includes infection prevention and control measures for animal workers, farm visitors and those who may be involved in animal husbandry or culling.
The basic principles to reduce the general risk of transmission of acute respiratory infections are as follows:
Avoiding close contact with people suffering from acute respiratory infections;
Ensuring frequent hand-washing, especially after direct contact with ill people or their environment;
For people with symptoms of acute respiratory infection, practicing cough etiquette, such as maintain distance, cover coughs and sneezes with disposable tissues or clothing, and wash hands; use of masks where appropriate; and
Enhancing standard infection prevention and control practices in hospitals in health care facilities, especially in emergency departments.
WHO advises against the application of any travel or trade restrictions for Denmark based on the information currently available on this event. WHO has issued guidance for Public health considerations while resuming international travel, recommending a thorough risk assessment, taking into account country context, the local epidemiology and transmission patterns, the national health and social measures to control the outbreak, and the capacities of health systems in both departure and destination countries, including at points of entry. In case of symptoms suggestive of acute respiratory illness either during or after travel, the travellers are encouraged to seek medical attention and share their travel history with their health care provider. Health authorities should work with travel, transport and tourism sectors to provide travellers with information to reduce the general risk of acute respiratory infections via travel health clinics, travel agencies, conveyance operators, and at points of entry.
For more information, see:
WHO Health Topics page on COVID-19
WHO Scientific brief on the transmission of SARS-CoV-2: implications for infection prevention precautions
WHO Public health considerations while resuming international travel
OIE Update 6 on the COVID-19 situation in mink in Denmark
OIE Technical factsheet, infection with SARS-CoV-2 in animal
OIE Questions and Answers on COVID-19
FAO Exposure of humans or animals to SARS-CoV-2 from wild, livestock, companion and aquatic animals
Based on a new risk assessment from the Danish health authorities, the Danish government has decided to cull all Danish mink herds. This follows the discovery of a new mutated virus.
Published 5. November 2020
The Danish government has decided to cull all mink in Denmark.
This is based on the fact that the Danish health authorities (Statens Serum Institut) in preliminary studies have found a new mutated COVID-19 virus in mink that can affect the effect of a vaccine.
- We are facing one of the biggest health crisis the world has ever experienced. The Danish government and I are painfully aware of what this means for all the Danish mink farmers who are about to lose their livelihood and for some their entire life's work. But it is the right thing to do in a situation where the vaccine, which is currently the light at the end of a very dark tunnel, is in danger, says Minister for Food and Fisheries Mogens Jensen.
Dangerous reservoir of infection
In mid-June this year, the first mink farms in Northern Jutland were found infected with COVID-19, and the virus has since spread to 207 farms spread across Jutland, counted 4 November 2020.
The Danish health authorities (Statens Serum Institut) have previously found various mutations of COVID-19 in Danish mink, and on the recommendation of the Danish veterinary and health authorities, the Danish government decided on 1 October 2020 to cull all infected mink herds and herds within a radius of 7,8 kilometers.
The Danish health authorities (Statens Serum Institut) have now found a mutation in tests from five mink farms in Northern Jutland and in tests from 12 persons and testing shows that the potential vaccines would not work effectively on this mutated virus .
At the same time, mink farms constitute a large virus reservoir that increases the risk of several new virus mutations.
Minister for Health Magnus Heunicke says:
- The Danish health authorities assess thadt mink farming during the ongoing COVID-19 epidemic entails a possible risk to the public health - and for possibilities to combat COVID-19 with vaccines. The Danish health authorities (Statens Serum Institut) have found a mutation and preliminary studies suggest that this mutation may affect the effectiveness of the current candidate for a vaccine against COVID-19. However, there is no evidence that those people infected with this mutation experience a more serious disease. A large virus reservoir of mink increases the risk of mutations re-emerging, which increases the risk that vaccines will not provide optimal protection. Taking into account the current situation in Northern Jutland, we unfortunately have to look at a number of local initiatives and further restrictions to contain the virus.
Incentive for mink farmers
It is crucial that the culling of the minks takes place quickly.
Thus, the Danish government is now introducing an economic incentive of 20 DKK for each mink if the mink farmer cull his herds within 10 days – or 5 days for herds under 7.500 animals.
Likewise, the Danish Police and the Danish Armed Forces will intensify their efforts.
- The Danish government will appeal to the sector and the mink farmers to support and contribute to this effort, although I understand that it will be a very difficult task for the farmers that will have to cull all their animals, says Minister for Food and Fisheries Mogens Jensen.
More information:
Ministry of Environment and Food, phone +45 2091 5901
Ministry of Health, phone +45 2132 4727
MONDAY, NOVEMBER 9, 2020
WISCONSIN MINK Between two farms more than 5,400 mink have died said Kevin Hoffman public information officer Division of Animal Health
MONDAY, NOVEMBER 9, 2020
Michigan Mink Farm Tests Positive with SARS-CoV-2
USDA Confirms SARS-CoV-2 in Mink in Utah after unusually large numbers of mink died at the farms
USDA Confirms SARS-CoV-2 in Mink in Utah
USDA Animal and Plant Health Inspection Service sent this bulletin at 08/17/2020 12:55 PM EDTWashington, D.C., August 17, 2020 -- The United States Department of Agriculture’s (USDA) National Veterinary Services Laboratories (NVSL) today announced the first confirmed cases of SARS-CoV-2 (the virus that causes COVID-19 in humans) in mink at two farms in Utah. These are the first confirmed cases of SARS-CoV-2 in mink in the United States. The affected farms also reported positive cases of COVID-19 in people who had contact with the mink.
After unusually large numbers of mink died at the farms, the Utah Veterinary Diagnostic Laboratory completed necropsies on several of the affected animals. Samples were forwarded and tested presumptive positive for SARS-CoV-2 at the Washington Animal Disease Diagnostic Laboratory. Both laboratories are members of the National Animal Health Laboratory Network. The presumptive positive samples were then sent to NVSL for confirmatory testing.
Mink were known to be susceptible to SARS-CoV-2, as the virus was discovered in mink on multiple farms in the Netherlands. Those affected farms also experienced an increase in mink deaths. Affected mink farms have also been identified in Spain and Denmark. USDA has closely monitored these outbreaks and recently issued a document containing guidance for farmed mink in the United States. There is currently no evidence that animals, including mink, play a significant role in spreading the virus to humans. Based on the limited information available to date, the risk of animals spreading SARS-CoV-2 to people is considered to be low. More studies are needed to understand how different species may be affected by the virus that causes COVID-19, and whether animals may play a role in the spread of the virus.
NVSL serves as an international reference laboratory and provides expertise and guidance on diagnostic techniques, as well as confirmatory testing for foreign and emerging animal diseases. Such testing is required for certain animal diseases in the U.S. in order to comply with national and international reporting procedures. The World Organisation for Animal Health (OIE) considers SARS-CoV-2 an emerging disease, and therefore USDA must report confirmed U.S. animal infections to the OIE.
People with COVID-19 can spread the virus to animals during close contact. It is important for people with suspected or confirmed COVID-19 to avoid contact with pets and other animals to protect them from possible infection.
TUESDAY, AUGUST 18, 2020
USDA Confirms SARS-CoV-2 in Mink in Utah after unusually large numbers of mink died at the farms
FRIDAY, JULY 17, 2020
Spain to cull nearly 100,000 mink after coronavirus outbreak at farm 86.67% of the samples positive
New research findings in the ongoing investigation into COVID-19 at mink farms suggest there has been a transmission of new coronavirus from mink to human
New results from research into COVID-19 on mink farms
News item | 19-05-2020 | 23:15
New research findings in the ongoing investigation into COVID-19 at mink farms suggest there has been a transmission of new coronavirus from mink to human. The investigation has also shown that mink with COVID-19 can be asymptomatic. Based on this new information, agriculture minister Carola Schouten and health minister Hugo de Jonge are introducing new measures.
'These new findings have a major impact on mink-farm owners and staff and their families, as well as on local communities,’ said Ms Schouten. ‘I'm in close contact with all those involved.’
The virus that causes COVID-19 mutates relatively quickly. These changes to its genetic code can be tracked. By comparing the genetic codes of the virus in different animals and people, scientists can create a ‘family tree’ for the virus and gain more insight into when and where people and animals were infected. This type of tracking has been done in the case of infected mink and people. The virus found in one staff member on a mink farm showed similarities to that found in the mink on that farm. Based on this comparison and the position of that form of the virus in the family tree, the researchers concluded that it is likely that one staff member at an infected farm has been infected by mink.
In order to clarify this finding, researchers are now continuing to map the genetic family tree of the virus in infected people in the area surrounding the mink farm in question. This will allow them to build as complete a picture as possible.
According to the National Institute for Public Health and the Environment (RIVM) the risk of the virus being transmitted from mink to human outside mink sheds remains negligible. RIVM made this risk assessment previously, after no samples of air and dust collected outside mink sheds were found to contain any trace of the virus.
Measures
Based on the new information, the government is introducing new measures on top of those already in force. Mink at all farms in the Netherlands will be screened for antibodies. In the interest of staff members’ health, it is important to gain a clear picture of the situation at all mink farms. Screening will be compulsory and will be coordinated by the Netherlands Food and Consumer Product Safety Authority (NVWA).
If a case is found at a mink farm, the same measures will be introduced as at other infected farms and staff members will be advised to use personal protective equipment at work. Furthermore, no visitors will be admitted to mink sheds on infected farms. Agriculture minister Carola Schouten had already imposed a reporting obligation on mink farm owners, veterinarians and staff at research institutes. That obligation will now be expanded, so that all symptoms pointing to COVID-19 must be reported to the NVWA. This is in addition to an existing ban on the removal of animals and manure from infected farms, a measure aimed at stopping the virus spreading to other farms.
Farm cats
This ongoing research has revealed a close similarity between the viruses found on two of the infected mink farms. There are several possible explanations for this. On one of the infected farms, antibodies to the virus were found in three out of 11 farm cats. It is therefore important to examine the potential role of farm cats in transmitting the virus. Farm cats are feral or semi-feral cats that live out-of-doors on a farm. Pending further research, mink-farm owners are advised to ensure that cats cannot enter or exit the site.
Pets
It is known that pets can contract COVID-19. The risk of people being infected by their pet remains small. RIVM’s existing advice regarding COVID-19 and animals remains unchanged: keep pets indoors if anyone in your household has COVID-19-like symptoms and the animal may have been infected. If you are in any doubt or if your pet has severe symptoms, always contact your vet. RIVM’s advice on pets can be found in full at RIVM.nl.
https://www.government.nl/latest/news/2020/05/19/new-results-from-research-into-covid-19-on-mink-farms
UESDAY, JUNE 2, 2020
USDA APHIS Confirmation of COVID-19 in Pet Dog in New York
WEDNESDAY, APRIL 22, 2020
APHIS Confirmation of COVID-19 in Two Pet Cats in New York
WEDNESDAY, JULY 8, 2020
Texas TAHC Household Dog Confirmed with Virus That Causes COVID-19
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W.H.O. Coronavirus disease (COVID-19) pandemic
Comparative Pathogenesis of Bovine and Porcine Respiratory Coronaviruses in the Animal Host Species and SARS-CoV-2 in Humans
Linda J. Saif, Kwonil Jung Alexander J. McAdam, Editor DOI: 10.1128/JCM.01355-20
REPORT
Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS–coronavirus 2
View ORCID ProfileJianzhong Shi1,*, View ORCID ProfileZhiyuan Wen1,*, View ORCID ProfileGongxun Zhong1,*, View ORCID ProfileHuanliang Yang1,*, View ORCID ProfileChong Wang1,*, View ORCID ProfileBaoying Huang2,*, Renqiang Liu1, Xijun He3, Lei Shuai1, Ziruo Sun1, Yubo Zhao1, View ORCID ProfilePeipei Liu2, Libin Liang1, Pengfei Cui1, Jinliang Wang1, View ORCID ProfileXianfeng Zhang3, Yuntao Guan3, View ORCID ProfileWenjie Tan2, View ORCID ProfileGuizhen Wu2,†, View ORCID ProfileHualan Chen1,†, View ORCID ProfileZhigao Bu1,3,† See all authors and affiliations
Science 29 May 2020: Vol. 368, Issue 6494, pp. 1016-1020 DOI: 10.1126/science.abb7015 Article Figures & Data Info & Metrics eLetters PDF Alternative hosts and model animals The severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) pandemic may have originated in bats, but how it made its way into humans is unknown. Because of its zoonotic origins, SARS-CoV-2 is unlikely to exclusively infect humans, so it would be valuable to have an animal model for drug and vaccine development. Shi et al. tested ferrets, as well as livestock and companion animals of humans, for their susceptibility to SARS-CoV-2 (see the Perspective by Lakdawala and Menachery). The authors found that SARS-CoV-2 infects the upper respiratory tracts of ferrets but is poorly transmissible between individuals. In cats, the virus replicated in the nose and throat and caused inflammatory pathology deeper in the respiratory tract, and airborne transmission did occur between pairs of cats. Dogs appeared not to support viral replication well and had low susceptibility to the virus, and pigs, chickens, and ducks were not susceptible to SARS-CoV-2.
Science, this issue p. 1016; see also p. 942
Abstract
Severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) causes the infectious disease COVID-19 (coronavirus disease 2019), which was first reported in Wuhan, China, in December 2019. Despite extensive efforts to control the disease, COVID-19 has now spread to more than 100 countries and caused a global pandemic. SARS-CoV-2 is thought to have originated in bats; however, the intermediate animal sources of the virus are unknown. In this study, we investigated the susceptibility of ferrets and animals in close contact with humans to SARS-CoV-2. We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but ferrets and cats are permissive to infection. Additionally, cats are susceptible to airborne transmission. Our study provides insights into the animal models for SARS-CoV-2 and animal management for COVID-19 control.
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In summary, we found that ferrets and cats are highly susceptible to SARS-CoV-2; dogs have low susceptibility; and pigs, chickens, and ducks are not susceptible to the virus. Unlike influenza viruses and the other SARS-coronavirus known to infect humans (SARS-CoV-1), which replicate in both the upper and lower respiratory tract of ferrets (20, 22–24, 26, 27), SARS-CoV-2 replicates only in the nasal turbinate, soft palate, and tonsils of ferrets. SARS-CoV-2 may also replicate in the digestive tract, as viral RNA was detected in the rectal swabs of the virus-infected ferrets, but virus was not detected in lung lobes, even after the ferrets were intratracheally inoculated with the virus. It remains unclear whether the virus causes more severe disease in male ferrets than in female ferrets, as has been observed among humans (13, 28).
Several studies have reported that SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as its receptor to enter cells (3, 29–31). ACE2 is mainly expressed in type II pneumocytes and serous epithelial cells of tracheo-bronchial submucosal glands in ferrets (25). Ferrets and cats differ by only two amino acids in the SARS-CoV-2 spike-contacting regions of ACE2 (table S1); therefore, the underlying mechanism that prevents the replication of SARS-CoV-2 in the lower respiratory tract of ferrets remains to be investigated. The fact that SARS-CoV-2 replicates efficiently in the upper respiratory tract of ferrets makes them a candidate animal model for evaluating the efficacy of antiviral drugs or vaccines against COVID-19.
The cats we used in this study were outbred and were susceptible to SARS-CoV-2, which replicated efficiently and was transmissible to naïve cats. Cats in Wuhan have been reported to be seropositive for SARS-CoV-2 (32). Surveillance for SARS-CoV-2 in cats should be considered as an adjunct to elimination of COVID-19 in humans.
W.H.O. SARS-CoV-2 mink-associated variant strain – Denmark
November 09, 2020
Terry S. Singeltary Sr.
