First reported case of Covid-19 transmission from cats to humans

So far, only two species are known to be able to transmit the COVID-19 virus to humans. Mink and hamster. The first undoubtedly contributed to the spread of the virus among mink breeders. Especially in the Netherlands and Denmark. A situation that led to the slaughter of several million animals. Pet hamsters are believed to have triggered an outbreak of the SARS-CoV-2 delta variant in Hong Kong earlier this year. The cat is now the focus of public health attention. Indeed, a Thai veterinarian tested positive for COVID-19 after one of her “patients” sneezed in her face.

Several animals infected with Covid-19 around the world

As noted in this August 2021 World Organization for Animal Health report, several countries have already reported cases of COVID-19 infection in various animal species, including mink, cats, dogs, tigers and lions (in descending order of incidence). . In particular, OMSA reports more than a hundred cases involving cats.

However, with the exception of minks, most of these infections resulted from human-to-animal transmission of the virus (known as reverse zoonosis). For the first time, scientists report suspected zoonotic transmission of SARS-CoV-2 from cats to humans. Their study appeared in the journal New infectious diseasespublished by the Centers for Disease Control and Prevention.

Timeline of the potential first cat-to-human transmission of COVID-19 that occurred in Thailand in August 2021.

On August 15, 2021, a 32-year-old formerly healthy veterinarian who lived alone was admitted to the hospital in Songkhla, southern Thailand; she had a fever, a clear runny nose, and a productive cough for two days. When asked about her past, she told doctors that five days earlier, she and two colleagues had examined a cat belonging to a man and his son.

Both father and son both tested positive for SARS-CoV-2 and were then transferred to isolation at the university hospital. Their ten-year-old cat also tested positive. However, during sampling, while being held by two other veterinarians, the cat sneezed in front of the veterinarian performing the PCR test; she was wearing a mask and gloves, but no goggles.

Transmission confirmed by genomic sequencing

Veterinarian tested positive for SARS-CoV-2! However, none of her close contacts (including two other veterinarians who assisted her) contracted COVID-19. This suggests that she was infected by a cat. Genetic research confirmed this hypothesis! The genomic sequences of the virus were identical, indicating that the veterinarian was infected with the same variant as the cat and its owners. In addition, the identified genome was different from that of other patients from the same province.

The identical genomic sequences of SARS-CoV-2 obtained from a patient and those obtained from a cat and two of its owners, as well as the temporal overlap of animal and human infections, indicate that their infections were epidemiologically linked. “.

Contact tracing of 30 employees of the veterinary hospital revealed another case of COVID-19 infection. Veterinarian who worked in another service. However, this patient did not participate in the case considered here. Because he developed a fever 24 hours before the cat’s arrival and had no direct or indirect contact with the cat, its owners, or its colleague. Also, his viral genome was different.

Read also: Covid Infection: Why Doesn’t the Vaccine Prevent Infection?

A route of infection that remains anecdotal

It was already known that cats can become infected with SARS-CoV-2 through close contact with their owner, especially if the latter has a symptomatic infection. Research published in 2020 in The science showed that cats are susceptible to airborne transmission. It also showed that their incubation period and infection period are relatively short. The researchers believe that this cat likely contracted COVID-19 in a week or less before passing it to the veterinarian.

The meeting with the cat lasted only ten minutes. But the vet was very close to him. And the viral load in the animal at that time was especially high, the authors of the study specify. His ocular surface was exposed and therefore vulnerable to infection! Because the patient wore gloves and washed her hands before and after examining the cat, the hypothesis of infection through direct or indirect contact (eg, through contaminated surfaces) was considered less likely.

This study provides evidence that the SARS-CoV-2 virus can be transmitted from cats to humans. But experts want to reassure. This mode of transmission is relatively rare due to the short period during which cats can shed virus particles. This period is estimated at an average of 5 days. To date, animals do not play a significant role in the spread of the virus. Humans remain the main source of the virus. However, they recommend that people with suspected (suspected or confirmed) COVID-19 should refrain from contact with their cat.

Read also: This is how SARS-CoV-2 creates ‘ghost ships’ in the brain


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