Russia has been dealing with African swine fever (ASF) in its swine herd since 2007 and the virus keeps marching across the country. This has prompted serious concerns about the prospect of the virus spreading into other Eastern European countries.

Now, a southern Russian farm had to slaughter all 30,736 of its pigs because of ASF, reports Bloomberg News. The pigs belonged to the Plemzavod Industrialny farm, located in the southern Russian Krasnodar region.

These hogs generally went to supply pork to local markets in the region, according to Alexei Alekseenko, a spokesman for Rosselkhoznadzor, Russia’s food-safety agency.

This marks the country’s largest outbreak of the virus, and consequent culling. The animal carcasses are typically burned and buried.

ASF was reported in a major agricultural breeding plant located a few kilometers out of Timashevsk city earlier this week. In that complex 98 pigs deaths had been registered.

According to the region’s veterinary services officials, pig deaths also were registered in several nearby private farms, and there is suspicion that the animals also died from ASF.

In response to the virus spread, veterinary officials at the Timashevsky district were fired, Alekseenko said. A farm worker who kept his own hogs probably brought the virus in to the larger herd, he added.

This week’s events follow an early December outbreak involving three regions—Volgograd, Tver and Saratov.

According to Nikolai Vlasov, Russia’s chief veterinary inspector, the ASF situation in the Russian Federation is “progressively getting worse.” It has has been discovered in 21 of Russia’s 83 regions so far, according to Rosselkhoznadzor data.

Bloomberg News contributed to this report.