In late June, a group of researchers from Thailand reported the first known case in which a human caught Covid after coming into contact with a cat that was infected with the coronavirus.
This is the fourth animal species in which infection with the pathogen and the possibility of transmitting the disease to people have been documented — the other three are mink, hamsters and white-tailed deer.
But, after all, can pets really get covid? The answer is yes, and there are several studies that confirm this possibility.
However, as far as is known, these cases are rare and the infection tends to be much milder in them.
BBC News Brasil heard experts to understand the potential risks of covid among pets – and if there is something that can be done to protect them.
The episode took place in August 2021 in the city of Bangkok, capital of Thailand. The full report on the case was published at the end of June this year in the specialized scientific journal Emerging Infectious Diseases.
A father and son, whose identities were withheld, were diagnosed positive for covid and, following the local recommendation, were transferred to an isolation unit in the city of Songkhla, located in the south of the country.
In the temporary move, they took a cat, who stayed in the same room with them for a few days.
Afterwards, the animal was transferred to a veterinary hospital, where it underwent an evaluation and some tests, which later proved that the kitty was also with covid.
During the consultation, when the vet swabbed the cat’s nose, he sneezed.
The professional wore a mask and gloves, but her eyes were unprotected – and it was probably at that moment that the transmission of the coronavirus to her happened.
Three days after the appointment, the vet had a fever, cough and sneezing. A test confirmed the diagnosis of covid in her as well.
But how do scientists know that the pathogen actually came from the cat? By analyzing the patient’s history, they saw that no close contact of her was with covid in those days (which decreases the likelihood that the infection came from another individual).
To complete, the authors of the work carried out genetic analyzes of samples taken from the father, son, veterinarian and cat. All had the same variant of the virus, with identical genetic sequences. This, in turn, reinforced the possibility that transmission happened through the cat.
In a zoo located in Belgium, a hippo was diagnosed positive for covid in December 2021 – Photo: Getty Images/Via BBC
A ‘return’ to nature?
The cat’s story in Thailand is far from unique.
Over the past two years, scientists from around the world have described other episodes of animals that have also become infected with the coronavirus and even developed some symptoms.
This was the case for several species that live in zoos and sanctuaries, such as lions, tigers, leopards, otters, gorillas, hyenas, coatis, hippos and even manatees.
Sars-CoV-2, the coronavirus responsible for the current pandemic, has also been found in pets, such as cats, dogs, hamsters and ferrets.
Sars-CoV-2 has also infected dogs, studies show – Photo: Getty Images/Via BBC
Most likely, all these animals had contact with caregivers and tutors who were with covid.
Some species, however, not only became infected, but there is also evidence that they transmitted the pathogen back to other humans.
For now, there are four episodes that fall into this category: the minks (or minks, animals used by the fur industry) in Europe, the hamsters in Hong Kong, the white-tailed deer in Canada and, more recently, the cat in Thailand.
This phenomenon is described among specialists with the term spillback (something like “retorno”, in free translation into Portuguese).
It is a process contrary to spillover (something like “overflow”), which happens when a pathogen that circulates in one species starts to affect some others.
The spillover is what probably happened with Sars-CoV-2: the most accepted thesis is that it only infected bats in Southeast Asia when it suffered a series of genetic mutations that allowed it to “jump”, or “overflow”, to humans and began to be transmitted from person to person.
“About 75% of the infectious diseases that affect us came from other animals. The viruses, bacteria, fungi and protozoa are there, in the natural host, like a wild animal, they mutate and acquire an affinity for a new host”, details molecular biologist Ana Gorini da Veiga, professor at the Federal University of Health Sciences in Porto Alegre (UFCSPA).
In Hong Kong, hamsters sold at a pet shop caught covid and transmitted it to people — Photo: Getty Images/Via BBC
The researcher recalls that this was not the first time that a coronavirus “jumps” to humans in the last two decades. In 2002, Sars-CoV passed through bats and civets until it reached us. As early as 2011, Mers-CoV, previously restricted to bats, camels and dromedaries, gained the ability to circulate among people.
In parallel with the spillover, the spillback also happened with the cause of covid, Sars-CoV-2: several species of animals, which were previously not affected by this pathogen, also began to be infected from 2020 onwards.
Despite the documented cases, experts heard by BBC News Brazil understand that infection by Sars-CoV-2 is very rare in other animals.
“As much as there is a possibility of infection and it is no surprise to us, the affinity of this coronavirus with other species is very small”, explains virologist Paulo Eduardo Brandão, from the Faculty of Veterinary Medicine and Animal Science at the University of São Paulo. .
And nothing indicates that the pathogen is evolving to more voraciously infect other beings besides humans themselves.
“Sars-CoV-2 is a very selective virus in terms of host. And the arrival of new variants shows that it is becoming more and more specialized in infecting us”, analyzes the scientist.
“Therefore, as far as we know so far, animals are of no importance in transmitting this pathogen and rarely develop symptoms.”
Minks (or minks) were one of the first species in which the infection and transmission of the coronavirus that causes covid was observed.
Some basic precautions
Should a person who has covid and needs to isolate at home take any special care with pets?
Specialists advise keeping a certain distance from the animal, if possible.
“Often, during quarantine, the animal is a great company. However, if you are going to stay in the same environment, it is worth keeping a distance, wearing a mask and reinforcing hygiene care”, guides Gorini.
Brandão reinforces that, if there is no way to restrict contact, maintaining contact with the pet will not pose a great threat. “We cannot repeat what happened in 2020, when several animals were abandoned by their owners,” he says.
“In other words: if you can isolate yourself and someone else takes care of the animal, better. But if you live alone or have no one to leave it with, you can keep the routine indoors”, he summarizes.
The US Centers for Disease Control and Prevention (CDC) advises that you should not put masks on animals – this can even cause some harm to their health.
There is also no need to apply alcohol gel, disinfectant or other cleaning products on the paws, fur or skin of pets.
Finally, it is always worth talking to the vet if your pet shows any atypical signs, abandons the routine, feels prostrate and stops eating, drinking water or pooping and peeing.
These symptoms could mean that he has an illness — and early diagnosis allows you to start treatment quickly.