Rome, 30 June 2022 – Covid, first documented case of cat-human infection. A group of researchers from Thailand has documented the case of a domestic cat that infected a person with the Sars-CoV-2 virus. He did this in a study published in Emerging Infectious Diseases. The findings add felines to the list of animals that can transmit the virus to people. The researchers say the results are compelling. They are surprised that it has taken so long to establish that transmission can occur, given the magnitude of the pandemic, the virus’s ability to jump between animal species, and the close contact between cats and people.
Animal-human transmission had already occurred with minks, for example in Denmark, since 2020.
Animal-human contagion
“We have known for two years that this was a possibility,” says Angela Bosco-Lauth, an infectious disease researcher at Colorado State University in Fort Collins on Scientific American.
Cats and Covid
Studies early in the pandemic found that cats spread infectious virus particles and can infect other cats. And over the course of the pandemic, countries have reported Sars-CoV-2 infections in dozens of domestic cats. But establishing the direction of viral spread – cat-to-person or person-to-cat – is complicated. The Thai study “is an interesting case and a great example of what good contact tracing can do,” says Marion Koopmans, a virologist at Erasmus University Medical Center in Rotterdam, the Netherlands.
The fatal sneeze
The discovery happened by accident, says study co-author Sarunyou Chusri, an infectious disease researcher and physician at the Prince of Songkla University in Hat Yai, southern Thailand. In August, a father and son who tested positive for SARS-CoV-2 were transferred to an isolation ward at the university hospital. Their ten-year-old cat was also swabbed and tested positive. During the swab, the cat sneezed in front of a vet, who was wearing a mask and gloves, but no eye protection. Three days later, the vet developed a fever, cold and cough and later tested positive for Sars-CoV-2, but none of his close contacts developed Covid-19. This suggested that he was infected with the cat. The genetic analysis also confirmed that the vet was infected with the same variant of the cat and its owners and that the viral genomic sequences were identical.
“Rare cases”
Researchers state that these cases of transmission from cat to man they probably are rare. Experimental studies have shown that infected cats don’t shed many viruses and only do so for a few days, says Leo Poon, a virologist at the University of Hong Kong. However, Chusri says it is worth taking extra precautions when handling cats suspected of being infected. People “shouldn’t abandon their cats, but take better care of them,” he says. Other animals suspected of infecting people include farmed mink in Europe and North America, domestic hamsters in Hong Kong, and wild white-tailed deer in Canada. Adding cats to the list “broadens our understanding of the zoonotic potential of this virus,” says Poon. But the researchers say these are all rare events, and animals do not yet play a significant role in the spread of the virus. “Humans are clearly still the main source of the virus,” says Bosco-Lauth.