The World Health Organization said that since Polish health authorities informed it last month of unusual cat deaths across the country, 29 cats had tested positive for H5N1 bird flu.
They were among 46 cats and one captive caracal tested for the virus, it said, adding that 14 of the infected animals were reported to have been euthanised, while another 11 had died.
The last death was reported on June 30.
“The source of the exposure of cats to the virus is currently unknown and epizootic investigations are ongoing,” WHO said in a statement.
Some cats developed severe symptoms including difficulty in breathing, bloody diarrhoea and neurological signs, with rapid deterioration and death in some cases.
Since late 2021, Europe has had its worst-ever outbreak of bird flu, while North and South America have also experienced severe outbreaks.
This has led to the culling of tens of millions of poultry worldwide, many with the H5N1 strain of the virus, which first emerged in 1996.
There has recently been a worrying spike in infections in mammals.
The UN health agency pointed out that sporadic infection of cats with H5N1 had previously been reported.
”But this is the first report of a high numbers of infected cats over a wide geographical area within a country,” it said.