Bats and pangolins aren’t the only wild animals harboring novel coronaviruses. Rodents such as rats, mice, and mice can also carry viruses that are sometimes able to jump into our species.
Among the branches of Swedish banks backed in red (Myodes glariolus), researchers have now identified a widespread coronavirus and named it the Grimsö virus, after its site of discovery.
We don’t know if the newly discovered virus poses a danger in any way to humans; However, the findings are a good reminder of why we need to monitor wildlife viruses, especially those carried by animals that live in close proximity to us.
“We still don’t know the potential threats the Grimsö virus may pose to public health. However, based on our observations and previous coronaviruses identified among bank mice, there is good reason to continue monitoring coronavirus among wild rodents,” says virologist Åke Lundkvist from Uppsala University in Sweden.
Bank rats are among the most common rodents found in Europe. Their paths often intersect with our own species, and they are known hosts of the Pumala virus, which causes the hemorrhagic fever known as epidemic nephritis in humans.
When seeking refuge from adverse weather conditions, rats have been known to take shelter in human buildings, and this increases our risk of contracting a disease that they transmit to our homes.
Even before the COVID-19 pandemic began, Lundkvist and his colleagues were trying to monitor wildlife diseases among mice, to better predict when their viruses could spread. Given the relentless pace of climate change and habitat destruction, there is every opportunity to increase our interactions with mice in the future.
Between 2015 and 2017, researchers in Uppsala examined 450 mare from wild bank branches from a site west of Stockholm called Grimsö. Testing the creatures for coronaviruses, the team found a new betacoronavirus circulating in 3.4% of the sample.
Betacoron viruses are usually found among bats and rodents, and when they jump into humans, they are responsible for causing colds and respiratory viruses such as SARS-CoV-2.
The new mare virus has not yet been detected in humans, but if COVID-19 teaches us anything, we need to increase wildlife disease surveillance to prevent further outbreaks.
Over the course of three years, researchers in Sweden have found several distinct viral strains of Grimsö virus circulating among bank rat populations.
Moreover, other closely related coronaviruses were widely distributed among mice in other parts of Europe, such as France, Germany and Poland, indicating that these organisms are the natural reservoirs of the disease.
The highly variable nature of the Grimsö virus is a bad sign. It indicates that the virus easily adapts to new hosts and habitats.
The different strains present in the circulation could have originally come from bank rats, or they may have jumped from another species.
“Given that bank rats are one of the most common rodent species in Sweden and Europe, our findings suggest that Grimsö virus may be widespread in bank rats, and also indicate the importance of surreptitious surveillance of coronaviruses in wild small mammals, especially in wild rodents,” the authors wrote.
Other studies have recently warned that human exploitation of wild places has directly increased the risk of transmitting animal diseases to humans. This danger was especially noticeable among animals such as bats, rodents, and primates, which have large populations and which have easily adapted to human environments.
While rodents and bats have long been considered vectors of human disease, they are not the only animals that infectious disease professionals need to keep an eye on.
Larger mammals, such as wild deer, are also in close contact with human civilization, and in the northeastern United States, nearly 40 percent of deer have been exposed to SARS-CoV-2.
Cattle, such as minks, have also entered the COVID-19 pandemic, and researchers fear that the virus could mutate between these host animals and reinfect us with another version of the disease in the future.
The fear eventually led to the culling of millions of farmed mink as a precaution. But eliminating entire populations of animals is not an acceptable solution, especially in the wild. Creating more environmental disruptions will only lead to more imbalances in ecosystems, stressing more animals and creating more opportunities for viruses. So improving monitoring will be key.
If weather and habitat destruction get worse in the future, we can coax new coronaviruses into our homes.
The study was published in Viruses.