A veterinary doctor in Thailand likely contracted the coronavirus from an infected pet cat last year, researchers conclude in a new study. It is the first documented case of suspected cat-to-human transmission, although experts emphasize that overall the risk of cats infecting people with the virus remains low.
One of the cat’s two owners, both with Covid-19, likely passed the virus to the cat, who sneezed in the vet’s face, according to the article written by scientists at Prince of Songkla University in Thailand.
Genomic sequencing confirmed that the cat and the three people were infected with an identical version of the virus, which was not widespread among the local population at the time. Cats are much more likely to catch the virus from people than to pass it on to them, scientists say.
But the case is a reminder that people infected with the virus should take precautions with their pets — and that veterinarians and shelter workers who may come into contact with infected animals should do the same, said Scott Weese, a disease veterinarian. infectious diseases at the University of Guelph in Ontario (Canada).
“When things become human illnesses, we often forget about everything else,” he said. “I think it’s important that we recognize that this virus can still move between species.”
Previous research has shown that pet owners can infect their cats and that under certain conditions cats can transmit the virus to each other. But it has been difficult to prove that cat-to-human transmission takes place in natural environments. (Mink, hamsters, and deer reportedly spread the virus to humans.)
The new paper was published this week in the journal Emerging Infectious Diseases, published by the US Centers for Disease Control and Prevention (CDC). That’s a strong case for cat-to-human transmission, Weese said: “They have a very good thesis here.”
On August 4, in Bangkok, a father and son developed symptoms of Covid-19 and later tested positive for the virus. Due to a lack of hospital beds in Bangkok, the two were transported by ambulance on August 8 to a hospital in Songkhla province in southern Thailand, on a 20-hour journey. For reasons that aren’t clear, they took their pet cat.
When the men were admitted to the hospital, the cat was referred to a veterinary hospital for examination. Although the cat appeared healthy, the 32-year-old veterinarian took nasal and rectal samples, which came back positive for the virus. As the vet examined the cat’s nose, it sneezed in its face. The vet was wearing gloves and a mask during the exam, but no eye or face protection.
On August 13, she developed symptoms of Covid-19, including fever and cough. Shortly after, she tested positive for the virus.
Genomic sequencing revealed that the cat’s owners, the cat and the vet were all infected with the same version of the delta variant, which was different from viral samples taken from other patients in Songkhla at the time.
The PCR test suggests that the cat had a high viral load at the time of the veterinary examination. None of the vet’s close contacts had Covid-19 at the time, and she had no previous encounters with the animal’s owners, supporting the theory that the cat was the source of the vet’s infection. (It was unclear whether she met with the owners later.)
The CDC recommends that people infected with the virus avoid contact with pets. “If you’re trying to stay away from people because it’s potentially infectious,” Weese said, “try to stay away from animals too.”
Translated by Luiz Roberto M. Gonçalves