Hundreds of domestic cats have been quarantined in New York City after contracting a strain of highly contagious avian flu.
The virus has also infected at least one veterinarian, officials say.
It is the first time the H7N2 strain of the virus, commonly found in birds, has infected domestic cats, according to the New York City Health Department.
Symptoms are generally mild, and include sneezing, coughing and runny eyes and noses.
The virus was first detected last month in 45 cats housed at a Manhattan shelter run by Animal Care Centre of NYC, and later turned up in cats at shelters in the boroughs of Queens and Brooklyn.
It was not immediately clear how the cats contracted the virus or how it spread so quickly, the city's health department said in a statement on Thursday.
"We continue to urge New Yorkers who have adopted cats from ACC shelters to be on alert for symptoms in their pets and take proper precautions," Health Commissioner Mary Bassett said in a statement.
She said the risk to human health from H7N2 is low.
H7N2 is a type of avian influenza virus, also known as the bird flu, that can mutate and transfer onto mammals such as cats.
More than 450 cats will remain at a temporary shelter for up to 90 days until a University of Wisconsin lab confirms they are no longer contagious, the city's health department said.
In December, the city's health department and the CDC confirmed that a veterinarian had been infected at the ACC's Manhattan shelter.
It was the first case of cat-to-human-transmission of the flu, the city's health department said. The illness was mild and short-lived.