The World Organisation for Animal Health said the outbreak, which was first detected on a cattle farm in the northwest near the border with Austria and Slovakia last month, has triggered border closures and the mass slaughter of cattle.
By Thursday, animal health authorities had inspected nearly 1,000 farms across Hungary. Of those, only four farms in the affected northwestern region returned positive results.
"At this stage, we can say that it cannot be ruled out that the virus was not of natural origin, we may be dealing with an artificially engineered virus," Prime Minister Viktor Orban's chief of staff Gergely Gulyas said at a media briefing