Since the beginning of 2020, the SARS-CoV-2 pandemic has caused more than 110 million cases and nearly 2.5 million deaths worldwide. But humans are not the only ones infected by this new coronavirus.
Since the beginning of the COVID-19 crisis, the scientific community has (albeit to a lesser extent) discovered the spread of the virus in certain animal species such as tigers, cats and minks, all of which are kept in captivity. Cats and ferrets, which belong to mink and ferrets, are particularly vulnerable to infection.
In fact, until January 2021, around 400 mink farms In eight European countries: 290 farms in Denmark, 69 farms in the Netherlands, 21 farms in Greece, 13 farms in Sweden, three farms in Spain, two farms in Lithuania, and one farm in France and Italy.
Therefore, the European Commission requires A report To the European Food Safety Authority (European Food Safety AgencyAnd the European Center for Disease Control and Prevention (Economic Cooperation and Development Committee, In English as an acronym) to determine the strategies used to monitor and control the spread of diseases in these farms.
in order to Alessandro Broglia (Monza, Italy, 1975) is a scientific expert in the animal and plant health department of the European Food Safety Agency (EFSA) and one of the authors of a book published last week. Surveillance activities in these places are a top priority. Animals in close contact with humans.
What are the main risks of virus infection for ferrets and humans and other animals (such as cats)?
As shown in our scientific report, SARS-CoV-2 infection, which is raised in large numbers in mink and other susceptible animals or in close contact with infected humans, may pose a major risk to human and animal health. In addition, facts have proven that there are cases of back propagation, from animals to humans working on mink farms. Therefore, due to the high level of human exposure to SARS-CoV-2, all mink farms should currently be considered at risk. Once introduced, the virus can spread efficiently in farms, and in the high-density areas of these farms, it is likely to spread to other people.
Will the variants of the virus related to mink increase this risk?
For virus variants related to mink, the protection of antibodies produced by vaccines or other variants of natural infection may be poor. However, it must be noted that the findings of this study are based on limited data, so the impact on the risk of reinfection, the efficacy of the vaccine or the benefit of treatment requires further research.
What preventive measures did they propose?
We recommend that first, closely monitor the emergence of new virus variants in mink and farm workers. As for cats, the report confirms that they may be included in the surveillance plan designed for these places because they are one of the species that has been shown to be susceptible and able to continue to spread the disease. You can also add ferrets, dogs and certain bats.
What symptoms will these animals have, and what effect does the virus have on them?
Both American mink and ferret are highly sensitive to SARS-CoV-2. The clinical signs of mink are similar to humans, and only part of it comes from infected animals. They are usually non-specific, such as increased mortality, mild respiratory symptoms and a slight decrease in food intake. Virus replication mainly occurs in the respiratory tract, while the digestive tract is the least affected.
Considering that only a part of the infected animals show clinical symptoms, EFSA believes that the follow-up strategy based on passive monitoring is not enough, and recommends active follow-up methods based on the early detection of infected animals.
Two specimens from a mink farm. /EFE/Raúl Sanchidrián
So far, what strategies have been adopted in different countries that have found positive cases in mink farms?
Each country has taken different measures to deal with this situation, but you must go back and start again. First, discover diseases in animals. To this end, a good follow-up strategy is the key. In fact, our scientific report focuses on proposing surveillance strategies that will help prevent and control the spread of SARS-CoV-2.
However, so far, some infected farms have been detected through passive monitoring, that is, workers have observed and reported abnormalities in clinical signs or production parameters (feed consumption, mortality, etc.). After an epidemiological association with SARS-CoV-2 in workers and everyone, another part was discovered after suspicion. Finally, active surveillance (active sampling and testing of 812 animals) was carried out to detect the remaining infected farms.
According to your report, when there are thousands of people in these institutions, how can the spread of the virus be controlled?
Once introduced, SARS-CoV-2 can spread efficiently in farms, and it is likely to spread to other people in areas with high density of mink farms. This is why the early detection and prevention of diseases is the key reason. This is why we recommend strict weekly testing for farm workers and all people who come into contact with animals and family members. This is the most important part of surveillance. More research should be conducted on farms with SARS-CoV-2 personnel experience.
What types of tests and measurements need to be performed?
It depends on the goal of the surveillance strategy. For early detection, EFSA experts recommend frequent and rigorous PCR tests on animals and people in contact with them. If a positive animal is detected, gene sequencing analysis must be performed to identify the source and source of the virus, so as to monitor the evolution of the virus and the possible emergence of new variants. In order to control the level of animal exposure to SARS-CoV-2, that is, to verify whether the animal population has been exposed to the virus, it can be assessed by collecting blood samples and performing serological analysis.
Can this strategy work with other animals (such as pets) that live with their families?
Yes, it is also a surveillance option for pets, especially ferrets (such as ferrets). Every time a suspicious animal (with clinical signs) or a SARS-CoV-2 case is found in a person in contact with it, the pet should be evaluated by PCR to confirm or rule out the infection.
In this case, how should the owner proceed? Do they go directly to the vet?
Yes, domestic ferrets and hunting ferrets are taken care of by veterinarians. These may be part of disease surveillance and take swabs and blood samples when in doubt, such as whether there are respiratory symptoms or diarrhea in the homeowner or home, death or suspected or confirmed cases of COVID-19. If someone in the household is infected, all ferrets and other susceptible pets, such as cats or dogs, should be tested.