At some time during the pandemic, the virus that causes Covid, Sars-CoV-2, went from humans to white-tailed deer in the US.
In 2021, researchers found that 40% of white-tailed deer tested in Michigan, Pennsylvania, Illinois, and New York state had Covid antibodies.
Scientists at Ohio State University have been keeping a close eye on these deer, and their recent study has shown that the virus is still spreading from the deer to humans. And it is changing quickly.
The scientists studied how common Covid was in a small group of white-tailed deer in north-eastern Ohio. The samples were collected from November 2021 to March 2022. Out of 1,522 samples taken from the nose, 163 showed signs of alpha and delta variants of COVID. The researchers also discovered that the virus had spread multiple times from people to deer and from deer to people (known as “spillover”).
Coronaviruses have spikes that attach to our cells to enter and start multiplying. The spikes attach themselves to a specific part of our cells called the ACE2 receptor. Deers and humans have a similar receptor. Coronaviruses have taken advantage of this quickly.
People often come into contact with deer in certain parts of the US. These areas have a large population of white-tailed deer that live in the wild or in urbanized and farmed areas. In these environments, deer may come into contact with human waste. They can carry germs that are resistant to medicine in a similar way as people who live in the same area.
The scientists in Ohio discovered that Covid increased and spread among deer for a period of time. The virus did not cause any noticeable sickness or deaths in the animals. Deer moving around the county, especially male deer, are spreading the virus.
We don’t know if animals like skunks, squirrels, or rodents also got the virus, but we know that it spread from deer to humans. We don’t know how this exchange occurred.
Deer on Staten Island, New York, also had signs of getting infected by a different Covid variant, called omicron, from people in the same timeframe. There are often viral interactions between communities and their deer.
The scientists in Ohio used a new way to study changes in the Covid virus in deer. They found that the virus mutates three times faster in deer compared to humans. The kinds of genetic alterations were different from the ones found in human Covid. The changes in the virus helped it spread more easily among the deer.
Covid changed and spread quickly among people, especially in the first few years after 2019.
Importantly, the transfer of the virus from deer to humans has not led to new outbreaks in humans that are worrying doctors. Changes in Covid in deer populations haven’t created a virus that can escape our antibodies. So right now, there is no danger to the overall public health from this higher rate of mutation.
Just like people, some deer can spread diseases very easily. Social network analysis reveals how male deer use scraping sites to establish breeding groups by leaving their scents behind. Feeding or bait stations created by humans for hunting make viruses spread faster.
White-tailed deer might have Covid viruses. Animal reservoirs refer to the ongoing cycle of viruses dividing and changing. The type of host affects how fast a virus’s genetic material changes. For instance, the flu virus changes faster in birds or pigs compared to humans.
Various factors like the length of time an infected animal lives, the chemical reactions happening in its cells, the body’s defense mechanisms, and the harm caused to the virus’ genetic material by enzymes or other infections can all contribute to viral mutation. For some reasons, these findings from Ohio suggest that the white-tailed deer population might develop a new type of Covid virus that can easily make humans sick.
In the year 2020-21, tests were done on deer in the UK to check if they had Covid. The results showed that there was no sign of the virus in these animals. This might be because different types of deer in Britain have distinct positions in their environment and are more or less prone to getting Covid. However, it is obvious that this continuous monitoring gives helpful information.