Brussels — The spread of African swine fever in Bulgaria, which threatens the Balkan country’s pig-breeding industry is worrying, an EU Commission spokesperson Anna-Kaisa Itkonen said on Thursday.

One of the EU’s poorest states, Bulgaria has reported more than 30 outbreaks of the disease — which is incurable in pigs but harmless to humans — at industrial or backyard farms. About 130,000 pigs have already been culled...