The new coronavirus has spread among deer? Can humans defeat the epidemic?

According to a Nature brief on April 26, a team of scientists conducted several years of tracking and testing on North American deer herds and found that white-tailed deer were infected with the coronavirus (COVID-19 or SARS-CoV-2). This has attracted the attention of scientists, who believe that once the new coronavirus enters the wild animal transmission chain, there will be no way to control it.

But so far, there is no definitive evidence that these deer infected with the new coronavirus will infect humans. A research team once believed that at least one new coronavirus case in humans could be traced back to the strain found in deer, but after reviewing the gene sequence of the virus in the deer, the Canadian Public Health Organization believed that there was no indication that it had been transmitted to humans and it might just be an "isolated case."

Scientists have been tracking viral infections in wild animals

For decades, researchers have been working with hunters to regularly monitor wildlife to detect the association between viruses in warning animals and humans. In North America, at least 30 million deer live with Americans, one deer for every 10 people. If viruses are transmitted to each other, it would be a major disaster.

Therefore, scientists have been tracking and managing infectious diseases in deer, such as chronic wasting disease and tuberculosis. Later, the new coronavirus epidemic emerged, and this virus was also included in the search plan. The new coronavirus test for deer is the same as that for humans, using swabs and blood tests.

The swab is also collected by inserting it into the nostrils of the deer, but the nostrils of the deer are deeper and require a longer swab; blood is collected to check for antibodies against the virus.

In early January 2021, researchers from the U.S. Department of Agriculture showed that captive fawns could be infected with the new coronavirus. Thomas DeLiberto, SARS-CoV-2 coordinator of the Wildlife Services Program of the U.S. Department of Agriculture's Animal and Plant Health Inspection Service, and his colleagues collected 385 blood samples from deer from January to March 2021, and found that about 40% of the samples contained SARS-CoV-2 antibodies.

Vanessa Hull, an animal health researcher at Ohio State University, has also been tracking and collecting samples from deer herds, but until December 2020, the samples were all negative; until January to March 2021, she and her university colleague, veterinary epidemiologist Andrew Bowman, collected samples from 360 white-tailed deer, of which 129 were found to be positive for SARS-CoV-2 viral RNA, accounting for about 35.8%.

Suresh Kuchipudi, a virologist at Pennsylvania State University in Park, and his team obtained similar positivity rates in Iowa. They tested 283 white-tailed deer between April 2020 and January 2021, of which 33% were positive for SARS-CoV-2, mainly in November and December 2020, when human infections peaked.

Deer have been found to be carrying SARS-CoV-2 in many places. After genetic sequencing of infected deer samples, it was found that the genetic mutations of the virus were similar to the mutations spreading in human society at the time. It was shown that these viruses had spilled over from humans six times, and mutations in the genetic sequences also confirmed the transmission of infection among deer.

Fortunately, there has been no evidence so far that any infected deer have reinfected humans with the virus.

The intermediate host of the new coronavirus remains a mystery

In nature, the virus itself is just a DNA or RNA nucleic acid, consisting of only a long nucleic acid chain and a protein shell. It has no metabolic mechanism or enzyme system, and is therefore a non-cellular substance with no activity and unable to replicate and reproduce itself independently. It can only be regarded as a chemical substance.

In order for a virus to survive, it must penetrate into cells and absorb nutrients from cells to feed itself, so as to achieve the purpose of replication and reproduction. Cells are the basic components of all life in the biological world. Therefore, when a certain cell is suitable for the survival and reproduction of a certain virus, the owner of this cell becomes the host of the virus.

Hosts include natural hosts, intermediate hosts and ultimate hosts. Natural hosts are organisms that provide a long-term, stable living environment for viruses but are not infected themselves; intermediate hosts are organisms that provide temporary protection for viruses and are not harmed by them. Viruses evolve through mutations in them and have the ability to attack ultimate hosts.

The ultimate host is the virus's final target host, which is the most suitable environment for the virus to eat, drink, defecate, urinate, and reproduce.

Unfortunately, humans have become the ultimate host of the new coronavirus. These tiny things, which can only be seen by humans when magnified more than 100,000 times, have devastated 7 billion humans like frightened birds, and there is smoke everywhere, but people have not yet found where it came from.

Based on years of research, scientists can only conclude that its natural host may be bats, and there has been no major breakthrough in what the intermediate host is. Therefore, many countries have been pushing for an independent investigation into the origin of the new coronavirus pandemic.

These investigations include modeling, cell research, and animal experiments, trying to find out the new coronavirus from various animals, as well as when, where, and how it entered the human population. Some people have suggested that the virus leaked from a laboratory, but these claims are nothing but speculation and malicious rumors, and there is no evidence to support them.

The natural host of the new coronavirus is bats. Thanks to the research of Chinese scientists, as early as 2013, scientists from the Wuhan Institute of Virology extracted a coronavirus genome sequence called RATG13 from horseshoe bats growing in Yunnan. This sequence has a similarity of 96% with SARS-CoV-2, making it the closest relative of the currently prevalent new coronavirus so far.

Therefore, this strongly suggests that the new coronavirus that began to spread in 2019 originated from bats, that is, bats are the natural host of the new coronavirus that is spreading this time. However, this sequence cannot directly attack the human body and must change itself through an intermediate host before it can cause human sensitivity.

There is no conclusion yet on what kind of animal this intermediate host is. However, there are many candidate animals that have entered the field of vision of scientists, such as pangolins, tree shrews, civets, ferrets, snakes, rhesus monkeys and hamsters, all of which are sensitive to coronaviruses.

Although these animals are susceptible to coronaviruses, it cannot be confirmed that they are the intermediate hosts of SARS-CoV-2. For example, through the study of coronaviruses in pangolins, it was found that they are too far away from the new coronavirus prevalent in humans and cannot be the direct ancestor of SARS-CoV-2.

Currently, the new coronavirus epidemic has long been transmitted directly from person to person, without the need for an intermediate host, but it is still important to find the intermediate host, which is very important for ultimately eliminating or isolating the harm of this virus to humans.

Can the new coronavirus be eventually eradicated?

My opinion is that it is difficult. One characteristic of viruses is that they cannot survive without a host. To eliminate any virus, we need to find out its natural host, intermediate host, and ultimate host.

Humans are the ultimate host of the new coronavirus. Humans can kill or isolate the new coronavirus from the human body through isolation, epidemic prevention, and drug treatment, but this does not mean that the virus has been eliminated, because these viruses still exist in intermediate hosts and natural hosts, they continue to mutate, and may come back at any time.

Scientists now have another concern, which is that the human coronavirus will break out among animals, especially wild animals, and then infect humans in turn, which would make it even more difficult to control.

Scientists have also tracked and tested domestic animals for nucleic acid, and found that pigs, chickens, and ducks are not susceptible to the coronavirus, making it difficult for them to become infected or spread. Cats and dogs are infected, but they show no symptoms and show no signs of spreading to humans. However, it is still recommended that people avoid contact with pets during the coronavirus epidemic, such as petting, being licked, and sharing food, as it is necessary to prevent risks.

Scientists believe that even if domestic animals or pets are infected, the virus can be controlled by isolating and killing them; if it becomes prevalent among wild animals and spreads back to humans, it will be out of control. Fortunately, this situation has not been discovered yet, but continued monitoring and investigation are necessary.

So, the novel coronavirus has been ravaging humans for more than three years. Can humans finally defeat it and return to normal life? I think it is absolutely possible, and it will happen soon. Because through the efforts of scientists, it has been confirmed that the novel coronavirus is only prevalent among humans so far, and there is only one way of transmission from person to person. In this way, as long as we work hard to control the spread of the virus among people, it is possible to put an end to this epidemic.

To relax control and lead a normal life, three basic conditions need to be met, namely:

1. The virus will continue to mutate and become weaker and weaker, eventually becoming a common infectious disease like influenza. Even if infected, it will not be fatal, or complications will rarely lead to fatality;

2. The vaccine has completely or largely controlled the infection and spread of the virus;

3. There is a specific medicine to treat this viral infection, which can kill these viruses as effectively as antibiotics can eliminate inflammation.

I think that with these basic conditions in place, this wave of the COVID-19 pandemic will be "eliminated" and people will be able to live a normal life. Many countries have already relaxed their control and returned to normal life. As a country with extremely strict control, when will we be able to relax? Let's wait and see.

But viruses are always mutating, they will still be brewing in natural hosts and intermediate hosts, and will come back once they have the chance. Therefore, humans should always be vigilant.

The most important thing is to change your living habits, especially those people who are mysteriously pursuing something original all day long, and who eat wild game, wild vegetables, live toads, and dead mice. They need to change themselves, pay attention to hygiene, and use scientific methods to guide their lives. Only in this way can they block the channels for virus invasion and make themselves and others happy.

What do you think about this? Welcome to discuss, thank you for reading.

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References:

https://www.nature.com/articles/d41586-022-01112-4

https://www.nature.com/articles/d41586-021-00531-z

https://www.nature.com/articles/d41586-020-01449-8

https://www.nature.com/articles/d41586-020-00984-8