COVID virus can evolve in animals, spawn variants that can come back to humans: Scientists


The role of ‘animal reservoirs’ in the spread of Covid is still being explored, but evidence of zoonosis, or the virus jumping from animals to humans, is mounting and scientists fear this new frontier could potentially spawn dangerous mutants and difficult to monitor.

Although there is no consensus on the origins of the SARS-CoV-2 virus, many scientists believe it likely jumped from bats to humans, either directly or through another species sold live at a market in Wuhan, China.

Some experts are also theorizing that the highly mutated variant of Omicron, which has caused a deluge of cases around the world, including India, emerged from animals, potentially rodents, rather than an immunocompromised human. “As the virus multiplies in infected hosts, it may mutate slightly, and the concern is that over time, minor genomic changes in hundreds or thousands or even millions of animals , could possibly add to changes that make the virus more contagious or more deadly in people, or able to evade treatments and vaccines,” U.S. public health expert Amita Gupta told PTI in an interview. by email.

Smaller SARS-CoV-2 mutations in animals can add up to make the virus more contagious or more deadly in humans, said the head of the Division of Infectious Diseases and professor of medicine at the medical school. from Johns Hopkins University.

The role of wildlife in the global epidemiology of SARS-CoV-2 may currently be insignificant, but the Covid pandemic is a stark reminder of the close connection between human and animal health. Although the number of people infected with evolved coronavirus variants in animals has yet to be quantified, evidence of zoonosis is mounting.

Last week, the Centers for Disease Control and Prevention (CDC) confirmed that at least four people in Michigan, US, had been infected with a version of the coronavirus seen primarily in mink in the first year of the pandemic.

Farmed mink and pet hamsters have been shown to be able to infect humans with the virus and a potential case of white-tailed deer to human transmission in Canada is currently under investigation.

Signaling the concern, the World Health Organization (WHO) said last month that the introduction of SARS-CoV-2 into wildlife could lead to the creation of animal reservoirs of the virus.

“Current knowledge indicates that wildlife does not play a significant role in the spread of SARS-CoV-2 in humans, but spread in animal populations may affect the health of those populations and may facilitate the emergence of new variants of the virus,” the WHO said. In addition to domestic animals, wild animals in the wild, in captivity or farmed such as big cats, mink, ferrets, deer, lions and great apes have been observed to be infected with SARS-CoV -2.

According to veterinarian Gaurav Sharma, a successful reservoir host is one where the virus can establish itself in the animal population through efficient intra-species transmission. These animals reintroduce the virus into the human population.

“While the virus replicates in a new host, it undergoes an adaptation process that can lead to mutation of the wild-type virus due to which new variants of the virus can emerge,” said Sharma, from the Center for Animal Disease Research and Diagnostics (CADRAD), in Bareilly, Uttar Pradesh, told PTI “In the face of declining community transmission among human populations due to various control measures, the importance of a reservoir potential animal among wild mammals increases. In such a case, the implications of animals returning to humans would be greater,” he said.

The researcher noted that this could also lead to the emergence of new variants as the virus adapts to the new animal host. This has been observed in mink farms in Denmark where transmission of the virus from humans to mink has led to the establishment of the virus in the new host and, in turn, the emergence of a circulating mink-associated variant. in man.

“This finding prompted the culling of mink on Dutch mink farms in early June 2020. This mink-derived line presented as a group 5 variant and showed evidence of immune evasion,” he said. declared.

Although the extent of the concern is difficult to gauge at this stage, it is cause for concern for humans for a variety of reasons, epidemiologist Dharmaveer Shetty agreed.

“If there are animal reservoirs, it becomes relatively more difficult to eradicate the virus, it becomes relatively more expensive to monitor the virus, and the likelihood of obtaining new variants also increases,” Shetty told PTI.

An increased number of host species (animals) that the virus can infect may result in an increase in the number of individuals among the expanded host base that can support the virus.

“This, in turn, will lead to increased multiplication of the virus due to the presence of an increased number of susceptible host individuals, leading to an increased chance and number of mutations under different conditions,” Shetty said.

Sharma added that the emergence of such variants affects the transmission dynamics of the virus in humans and can also reduce the effectiveness of currently used diagnostics and vaccines.

According to a recent peer-reviewed study, which has yet to be peer-reviewed, the first potential case of a deer transmitting the novel coronavirus to a person has been reported in Canada. He also identified highly mutated clusters of SARS-CoV-2 genomes in white-tailed deer, highlighting the deer’s potential to act as an animal reservoir for the virus.

Shetty said these results indicate the possibility of deer-to-human transmission, but it’s not yet definitive.

“Only after further study and monitoring will we have a better idea of ​​the real risk of animals transmitting new variants to humans,” he said.

To manage this final frontier in the fight against Covid, Shetty said it is important to monitor the virus in host animals to learn how the virus evolves and is transmitted.

“…Update the vaccine accordingly, maintain herd immunity of the human population through vaccination using regularly updated vaccines, and take preventive measures,” Shetty said.

Gupta noted that globally there is an unprecedented amount of animal health data and the dangers are still being investigated.

“We therefore want to continue to support and strengthen our health systems and approaches that enable understanding of human, animal and environmental interactions and data is important to support so that we can optimize our preparedness for Covid and other infectious diseases. emerging,” she added. .


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