A veterinarian in southern Thailand may have contracted the virus from a pet cat infected with COVID-19 last year, researchers conclude in a new study. This is the first documented suspected case of cat-to-human transmission, although experts stress that the risk of cats transmitting the virus to humans remains low overall.
According to a research paper written by scientists at Prince Songkla University, one of the cat's two owners, both infected with Covid-19, may have passed the virus to the cat, which then sneezed into the veterinarian's face. Genome sequencing confirmed that the cat and all three were infected with an identical virus, which was not common in the local population at the time.
Scientists say cats are far more likely to contract the virus from people than to transmit it to people. But Dr. Scott Wise, an infectious disease veterinarian at the University of Guelph in Ontario, Canada, said the case is a reminder that people infected with the virus should take protective precautions for their pets, and even more so for veterinarians and staff who may come into contact with infected animals.
"When a virus is involved in a human disease, we tend to forget about everything else," he said. "I think it's important for us to recognize that this virus can still be transmitted between species."
Humans shouldn't just be concerned about their well-being; the pets that accompany us as well as the animals in nature need to be protected.
Previous studies have shown that pet owners can infect their cats with the virus, and in some cases, cats can transmit the virus to each other. However, it is difficult to prove that cats can transmit viruses to humans. (Mink, hamsters, and deer have been reported to transmit the virus to humans.)
The new paper was published this week in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention. It provides strong evidence of transmission from cats to humans.
On August 4 of last year, a father and son in Bangkok showed symptoms of pneumoconiosis and subsequently tested positive. Due to a shortage of hospital beds in Bangkok, the two men were taken by ambulance for 20 hours to a hospital in Songkhla on Aug. 8. For reasons that are not clear, they brought their pet cat with them.
When the two men were admitted to the hospital, the cat was also taken to the veterinary hospital for examination. Although the cat appeared healthy, the veterinarian - a 32-year-old woman - took swabs of the cat's nose and rectum, which tested positive for the virus. As the veterinarian scrubbed the cat's nose, the cat sneezed into her face. (This veterinarian was wearing gloves and a mask, but no face shield or eye protection.)
On August 13, this veterinarian developed a fever and cough, among other symptoms. Shortly thereafter, she tested positive for the virus.
Genome sequencing showed that the owner, this cat and the veterinarian were all infected with the same version of the delta variant, which was different from the viral samples taken from the other patients in Songkhla at that time.
PCR testing indicated that this cat had a high viral load at the time of the veterinary examination. It is known that none of the veterinarian's close contacts at the time were infected with Covid-19, and she had no prior contact with the pet's owner, lending support to the veterinarian's theory that the source of the infection was the cat. (It is not clear if she subsequently met the owner.)
The U.S. Centers for Disease Control and Prevention recommends that people infected with the virus avoid contact with their pets. "If you're trying to stay away from people because you're potentially infectious," Dr. Weiss said, "then stay away from animals at the same time."
The probability of a pet transmitting the COVID-19 to a human is low, but the risk is still there. So when your pet shows flu-like symptoms, give it an Antigen Test and you'll know the results quickly and accurately.