How is the coronavirus mutating into different strains?

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The coronavirus has infected more than 1.3 million people across the planet and killed some 72,000.

Adding to the grim statistics, on Sunday, the Bronx Zoo announced that one of its tigers had tested positive, amid a swirl of concern that other cats were exhibiting similar symptoms of illness and distress.

Some researchers have been endeavoring to understand the vulnerability of different animal species to the contagion, officially termed COVID-19, and thus to determine how it disseminates among animals and whether it is indicative of new and equally as lethal deviations.

"Cats, including big cats, are known to be susceptible to coronaviruses, and it turns out COVID-19 is no exception. The mode of transmission appears to be one way—human to cat—and there is no evidence yet of transmission the other way," Dr. Summer McGee, dean of School of Health Sciences at the University of New Haven, told Fox News. "Even so, the CDC is recommending COVID-19-positive patients isolate from house cats as we do not yet know the health consequences for our pets, nor do we know absolutely that they aren't asymptomatic carriers."

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Animal-to-human transmission of coronavirus has not been ruled out, but there is no evidence that it has already taken place – yet. According to McGee, the novel infection in multiple species of cats suggests that many more mammals, besides humans, could be impacted by this global pandemic.

"This could have major consequences for not only our domesticated animals but for global agriculture, zoos, and our ecosystem broadly," she surmised. "We will need to, just as in humans, start regularly testing for COVID-19 to understand which species are at risk and what the health consequences are for these animals."

People work in a lab that President Donald Trump watched during his meeting about the coronavirus at the Centers for Disease Control and Prevention, Friday, March 6, 2020 in Atlanta. 

People work in a lab that President Donald Trump watched during his meeting about the coronavirus at the Centers for Disease Control and Prevention, Friday, March 6, 2020 in Atlanta.  (AP Photo/Alex Brandon)

As it stands, the virus is mutating among humans. And the more it rages on, the more it changes. At least eight strains of the pathogen have been identified, indicating that it has amended itself several times since "patient zero" was presumably infected at a wet market in Wuhan, China, late last year.

Dr. Imran Sharief, a California-based pulmonary and critical care physician emphasized that animals are only carriers; thus, the same strain is noted in both humans and animals. In terms of the Bronx Zoo diagnosis, while no further sequencing details have been issued, it is assumed that the tiger has the same genomic code, and the virus is not mutating in animals.

But according to scientific finds so far, the mutations appear relatively minor and are not a massive cause for alarm – at least as it currently stands. The strains identified so far do not appear to be growing more deadly as they derive, experts have said, but there are still many unknowns and unraveling mysteries surrounding the never-before-seen contagion to draw any conclusions.

Dr. Steven Berk, dean of the Texas Tech University Health Sciences Center and an infectious disease physician, has examined the six species of human coronavirus that have long been known prior to this outbreak. He said that four produce symptoms of the common cold and two are more serious.

"Those causing respiratory disease include Severe Acute Respiratory coronavirus or SARS, Middle East Respiratory Syndrome or MERS and now SARS CoV-2, which produces COVID 19," Berk explained.

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And it's the new pathogen – barely a few months old – that has world experts in a scramble to understand. When samples are taken, scientists across the world are uploading their findings into the NextStrain database. This allows all scientists, in real-time, to see the genome sequencing, which then illuminates the various virus subtypes and gives researchers an idea of how the virus is spreading globally.

It is estimated that the coronavirus currently afflicting the globe is mutating on average around every 15 days, according to National Geographic.

Whereas some countries may be limited to one of two strains of the disease, scientists surmise that given its foothold in all crevices of the United States, strains from all over have spawned – ranging from the original type out of Wuhan, China and subsequent varieties that have since ravished Iran, Italy and other hot zones.

Ascertaining how the coronavirus operates and alters – and which strains are dying out while others are thriving due to the various social isolation and hygiene guidelines imposed – are critical in the race to develop a vaccine. The shelter-in-place protocols which have been implemented in vast swaths of the country are not only recommended in curbing the spread but in killing off strains – or at least limit the transformation of new ones – thus making it easier for an effective vaccine to be concocted.

"The outbreaks are trackable. So far, most cases on the U.S. West Coast are linked to a strain first identified in Washington state. The man carrying that strain [came from] Wuhan, China. On the East Coast there are several different strains. We have close to 1 million cases and 1,000 genomes," Sharif said.

The genome of the SARS-CoV-2 ailment is comprised of some 30,000 base pairs and have made at least 11 base pair changes, those studying the matter have observed. Indeed, the breeds infecting Americans on the West Coast are believed to be the original strain and three other mutations from Washington, the primary hub of the homeland outbreak.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia. (Amin Nazari/ISNA via AP)

On the East Coast and on the streets of New York, which is now engulfed in cases and an ascending death toll, there are seemingly more varied strains – both the Wuhan paradigm and European offshoots, and now U.S., deviations.

"The SARS-CoV-2 genomic, molecular structure is closet to a coronavirus in bats," Sharif said. "50 percent of the virus genome is associated with travel — 30 percent associates with healthcare workers. Only 20 percent is from the community. What all this means is that social distancing is working."

Research so far suggests that the virus mutates especially slow – around eight times slower than influenza – and more in line with its viral sibling SARS.

"This virus is mutating but very slowly. Two separate strains were identified in China, but they were very similar," Berk observed. "The different strains that are in circulation are very similar in their RNA sequences. In fact, there is actually some optimism about developing a vaccine because of the slow mutations."

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But given the newness of the illness and how quickly dynamics are changing, analysts and experts expect the mutations to continue evolving – and can hope the changes remain relatively mild.

"There is much work on tracking mutations in the virus but no work to my knowledge of the implications of these differences on diseases," added Karla Satchell, a professor in the Department of Microbiology-Immunology at Northwestern University Feinberg School of Medicine. "All conclusions to that end are solely speculative."