Poolse zwanen en Oostenrijkse katten bezwijken aan het H5N1-virus (en)

Bird flu is continuing to spread in Europe with the Polish authorities confirming a case of H5N1 in dead swans and with three cats in Austria also testing positive for the deadly H5N1 strain.

In a statement, Polish authorities said that they are applying precautionary measures outlined by Brussels, including the establishing of a high risk area around each of the incidents and a surrounding surveillance zone of ten kilometres.

At the same time, Austria confirmed its first reported case of bird flu spreading to a mammal.

The three affected cats lived in an animal shelter, with about 170 other animals.

This is not the first time the strain has spread to cats, with Germany also finding an infected cat last month.

According to the New York Times, the recent outbreaks of bird flu have made European experts realise that they have much to learn about how migrating birds spread the H5N1 virus.

Vittorio Guberti, head veterinarian of the Italian National Institute for Wildlife is quoted as saying "We know next to nothing about this virus; we have only anecdotal information about where it exists and what birds it infects."

"We don't even know where to focus. We have to sit and wait for the big epidemic to occur, and in the meantime there will probably be small outbreaks all the time."

Scientist also do not know which species may be the major carriers of the virus.

The major worry is that it could eventually mutate to spread between humans, leading to a pandemic.