There's Bad News, Good News on Coronavirus' Spread in Cats
WEDNESDAY, May 13, 2020 (HealthDay News) -- With sporadic reports of tigers and housecats picking up the new coronavirus from nearby humans, a new trial gives more details on whether cats can pass the virus to each other.
The answer: Yes, and quite easily, according to the new trial involving six felines.
But there was good news, too: Even though cats can transmit the new SARS-CoV-2 virus to other felines, none of the kitties infected in the new study appeared to get sick.
Still, the team of American and Japanese researchers said that domestic cats "may be a silent intermediate host of SARS-CoV-2, because infected cats may not show any appreciable symptoms that might be recognized by their owners."
So far, however, there's been no evidence that cats can pass the virus to humans -- only evidence that humans might pass the virus to a pet cat.
In the study, a team led by Yoshihiro Kawaoka, of the University of Tokyo, first deliberately infected (via inoculation) three domestic cats with the new coronavirus. By three days after the inoculation, the virus was detected in nasal swab tests in all three cats.
At the same time, each of the three infected cats were paired with an uninfected cat on day 1 after their inoculation, with the pairs housed in close contact.
Within five days, "virus was detected [via nasal swab] in all three cats that were co-housed with the inoculated cats," the team reported May 13 in the New England Journal of Medicine.
However, none of the six cats in the study "showed any symptoms" of illness, including fever, eye infections or weight loss, the team said.
What does all this mean for people?
While there's as yet no evidence that an infected cat can pass the new coronavirus to humans, Kawaoka's group said it's not out of the realm of possibility.
The researchers pointed to cases in 2016, when "an H7N2 influenza outbreak in New York City cat shelters highlighted the public health implications of cat-to-human transmission to workers in animal shelters."
In that outbreak, "virus isolated from the infected human [worker] was closely related to virus isolated from a cat," researchers reported in the journal Emerging Infectious Diseases in 2017.
Right now, the U.S. Centers for Disease Control and Prevention's guidance on COVID-19 and animals states that, "based on the limited information available to date, the risk of animals spreading COVID-19 to people is considered to be low. We are still learning about this virus, but it appears that it can spread from people to animals in some situations."
More research is needed, however, according to the new study's authors.
"Given the need to stop the coronavirus disease 2019 pandemic through various mechanisms, including breaking transmission chains, a better understanding of the role cats may play in the transmission of SARS-CoV-2 to humans is needed," the researchers concluded.
Here's the full guidance on coronavirus and animals from the U.S. Centers for Disease Control and Prevention.
SOURCES: May 13, 2020, New England Journal of Medicine, online; December 2017, Emerging Infectious Diseases