Covid-19 has killed more than one million people worldwide and experts warn that it could become a ‘multi-species’ pandemic unless humans are careful not to infect wild animals.
Researchers have again found that the strain of coronavirus which causes Covid-19, called SARS-CoV-2, can infect many animal species and not just humans.
While the biggest threat is to animals which come into close contact with humans, such as pets, there is also a transmission risk for wild animals, including lions, tigers and apes.
And experts warn that if animals do become widely infected, they can act as reservoirs for the disease, leading to future reinfection and repeat outbreaks.
Separate research, published earlier this week, found at least 28 mammal species that come into regular close contact with humans can catch the virus.
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The study pointed out that conservationists, forestry workers, pest control staff and wildlife tourists could unknowingly transmit the virus to wild animals
Lead study author Dr Sophie Gryseels, from the University of Antwerp in Belgium, said: ‘It’s difficult enough to control the SARS-CoV-2 in human populations. Imagine what it will be like if it spreads among wild mammals.
‘They could also get sick and form a reservoir from which they can then again infect humans, but we can’t ask animals to wear face masks and keep physical distance.
‘Preventing human-to-wildlife SARS-CoV-2 transmission is important to protect these animals – some of which are classed as threatened – from disease but also to avoid establishment of novel SARS-CoV-2 reservoirs in wild mammals.
‘The risk of repeated re-infection of humans from such a wildlife reservoir could severely hamper SARS-CoV-2 control efforts.’
Scientists are confident that SARS-CoV-2 is capable of zoonotic transmission, jumping from one species to another.
Bats are immune to coronaviruses but harbour dozens of them in their systems, acting as potent reservoirs for the viruses which wreak havoc in humans.
They speculate that the SARS-CoV-2 virus evolved up to 70 years ago and resided in bats, unable to spread to another species.
However, it is though that the virus last year jumped into an intermediate species, potentially pangolins or wild dogs, before again jumping into humans, but there is much debate over this.
Irrespective of what the intermediate host was, the virus successfully made the jump into humans in Wuhan, China, late last year.
It then thrived, replicated and spread, triggering the devastating pandemic the world is grappling with today.
If a widespread infection of animals is discovered, it could lead to mass culling, similar to what happened when a mink farm in the Netherlands was found to be a coronavirus hotbed.
Previous studies have found humans can infect their cats or dogs with the virus, and it can also occur in a zoological setting.
But this latest research found there is a possibility it can also happen with wild animals.
In the study, scientists gathered data from several studies and reviewed all available information.
This was initially done in April, at the height of the pandemic, and then updated in July and August, as more literature emerged.
It revealed cats, American mink, raccoon dogs, Egyptian fruit bats, North American deer mice and Syrian hamsters can catch and spread coronavirus.
Tigers and lions can also catch the virus, and transmission from big cat to big cat is likely, but not currently known.
Domestic dogs, tree shrews and common marmosets also appear to be susceptible to the coronavirus but appear less likely to be able to pass on the virus.
It also found that most Old World Monkeys, such as apes, are likely to be susceptible, but New World primates, found in the tropical regions of Central and South America and Mexico, may be more resistant to the virus.
Scientists found hamsters may also be susceptible while house mice and rats appear not to be.
Dr Gryseels and her team warn that is the virus was to become prevalent among wild animals it would be almost impossible to contain the spread of the virus.
Scientists suggest precautions such as ‘physical distancing, wearing face masks and gloves, and frequent decontamination’ should be taken by people who come into direct and indirect contact with feral or wild animals to ensure the animals do not become infected
The study pointed out that conservationists, forestry workers, pest control staff and wildlife tourists could unknowingly transmit the virus to these wild animals.
Other groups include ecological consultancy workers, managers and staff of protected areas and natural environments, and staff in wildlife rehabilitation centres.
Scientists suggest precautions should be taken by people who come into direct and indirect contact with feral or wild animals.
Dr Gryseels said: ‘During such activities, we recommend sanitary precautions such as physical distancing, wearing face masks and gloves, and frequent decontamination, which are very similar to regulations currently imposed to prevent transmission among humans.
‘We further recommend active surveillance of domestic and feral animals that could act as SARS-CoV-2 intermediate hosts between humans and wild mammals.
Findings were published in the journal Mammal Review.