COVID-19 has been devastating for people across the world, with more than 5 million confirmed deaths globally. However, humans are not the only species that the SARS-CoV-2 virus can infect. In this Special Feature, we discuss recent research into animal populations that might harbor the virus.
Researchers believe that SARS-CoV-2 is a type of zoonosis — a disease that transfers from nonhuman animals to humans, often via an intermediary nonhuman animal with which humans have contact.
To date, scientists are not sure which species acted as the originator or the intermediary. However, all known human coronaviruses have their origins in nonhuman animals.
Experts believe that the meat markets of Wuhan, China, provided an opportunity for the SARS-CoV-2 virus to transfer from nonhuman animals to humans, as was the case with the original SARS-CoV virus in meat markets in China in 2002 and 2003.
As well as emerging from nonhuman animals, there is also evidence that SARS-CoV-2 has returned to other animal species.
Multiple recently-released reports have documented that SARS-CoV-2 has now also spread to white-tailed deer in the United States.
In a brief report in the Proceedings of the National Academy of Sciences of the United States of America, researchers tested the blood of 624 deer from four U.S. states before and during the pandemic. They found that 40% of the samples taken since the pandemic began contained SARS-CoV-2 antibodies.
In a preprint study that is yet to undergo peer review, researchers report that they detected SARS-CoV-2 in 129 out of 360 deer in northeast Ohio, using a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test.
In another preprint study, researchers used RT-PCR tests on lymph node samples that they had taken from 283 captive and wild deer. One-third of the samples were positive for SARS-CoV-2.
The presence of SARS-CoV-2 in animal populations is a concern for scientists, as it raises the possibility that a new variant of the disease, which could potentially be more dangerous, could cross back into human populations.
Speaking with Medical News Today, Dr. Graeme Shannon — a lecturer in zoology at the School of Natural Sciences in Bangor University, Wales — said:
“Animal reservoirs have the potential to generate mutations that the human immune system has not come into contact with before. We see this regularly with influenzas that hop readily from birds and a number of mammals back into humans.”
“However, equally, the disease may infect wildlife and mutate but become less of a threat to humans as it adapts to the biology of the current host.”
“Certainly, the presence of multiple animal reservoirs on top of the high prevalence of the disease in humans would be cause for concern. This could complicate our attempts to suppress the disease. Indeed, we have already seen that infected captive mink were able to reinfect farmworkers,” said Dr. Shannon.