The outbreak was detected after sampling at a breeding facility with parent broiler animals, according to the National Veterinary Institute (SVA).
The Swedish Board of Agriculture has decided to cordon off the farm and that almost 22,000 animals will be killed, the authority said in a press release. The buildings in question will then be cleaned up.
The virus in the current case is H5N1, a variant that has been circulating in Europe and Sweden since 2020.
"Despite occasional reports of cases in humans, the European Centre for Disease Prevention and Control (ECDC) still assesses that the risk of infection to humans is generally low," writes the Swedish Board of Agriculture.
First of the season
The infection is suspected to have entered the holding through spread from wild birds. The outbreak is the first case of bird flu at a commercial facility this season, according to the agency.
"It has so far been a relatively quiet season for Sweden, but the danger is not over. Now that the migratory birds are returning, it is extra important that you continue to be careful with your hygiene routines to avoid getting the infection to your animals", says Katharina Gielen, infection control manager at the Swedish Board of Agriculture in the press release.
Increased number of cases in Europe
In Europe, the number of cases in wild birds has increased in recent months. Laughing gulls have been particularly affected, according to the National Veterinary Institute.
"SVA therefore assesses that in the coming weeks there is a risk of increased spread of infection in connection with the spring migration," says Malin Grant, epidemiologist at SVA.
The virus is found, among other things, in the droppings of wild birds and can, for example, spread further via car tires and shoes.