Authorities in several countries in Central Europe are working to contain an outbreak of foot-and-mouth disease among cattle populations that has caused widespread border closures and required the killing of thousands of animals.

The outbreak was first detected on a cattle farm in northwestern Hungary in early March, and animals on three farms in neighboring Slovakia tested positive for the highly transmissible virus two weeks later.

Since then, animals from an additional three farms in Hungary and another three in Slovakia have tested positive for the virus, the first outbreak of the disease in either country in more than half a century.