PVD spokeswoman Anna Joffe told BNS that measures had been taken at the farm in Griskani district, the municipality of Rezekne, in south-eastern Latvia, to prevent the infection from spreading further.
The measures include establishing a protection zone three kilometers around the affected farm and a monitoring zone ten kilometers around it.
The movement of domestic pigs and wild boars, as well as animal transportation in the area will be closely monitored. A 40-day ban has been imposed on taking pigs or pork out of the territory, the representative of the veterinary authority said.
The last time a domestic pig tested positive for ASF in Latvia was on August 25 this year. This summer it's the largest farm where the dangerous disease has been found. All of the pigs have been culled.
Māris Balodis, the head of the PVD, said that, in this farm, all of the pigs were registered and the necessary security measures had been observed: "The farm has a fence around it, there are disinfection spots, so formally all of the requirements were met."
Epidemiologists of the PVD aren't sure how the infection had made its way into the farm.
"As opposed to previous cases, where fresh, green produce had been fed [to the pigs], here last year's grain was used [as food], so we have to find out other ways how the virus [can] enter the farm," said Balodis.
African swine fever is an extremely dangerous and contagious virus infection affecting pigs. If an infected pig is found in a farm all pigs in the particular farm have to be culled, which means big losses for farmers.
It first arrived in Latvia in June 2014, believed to have been carried across the border from Belarus by wild boar. A series of quarantine zones and culls in the months since have failed to stop its advance across Latvia and into Estonia.
Previously, the Latvian government, at Europe's behest, approved amendments in regulations on measures to prevent and eradicate the disease.