(Adds that chickens were for broiler flock, details)
March 5 (Reuters) - A strain of bird flu has been detected in a commercial chicken breeder flock in Tennessee's Lincoln County and the 73,500 birds will be culled to prevent the virus from entering the food system, U.S. and state agriculture officials said on Sunday.
The U.S. Department of Agriculture said this represented the first confirmed case of highly pathogenic H7 avian influenza (HPAI) in commercial poultry in the United States this year.
The facility has been placed under quarantine, along with approximately 30 other poultry farms within a 6.2-mile (10 km)radius of the site, the Tennessee state government said. Other flocks in the quarantined area are being tested for the virus, it added.
In 2014 and 2015, the United States killed nearly 50 million birds, mostly egg-laying hens, during a bout of HPAI. The losses pushed U.S. egg prices to record highs and prompted trading partners to ban imports of U.S. poultry.
No humans were affected in that outbreak. The risk of human infection in poultry outbreaks is low, although in China people have died this winter amid an outbreak of the H7N9 virus in birds.
HPAI bird flu was found in a commercial turkey flock in Indiana in January 2016 but there have been no other cases in commercial flocks until now.
The breeders at the Tennessee facility were for the broiler flock, USDA spokeswoman Donna Karlsons said in an email.
Neither the USDA nor the state named the facility involved.
In January, the USDA detected bird flu in a wild duck in Montana that appeared to match one of the strains found during the 2014 and 2015 outbreak.
In recent months, different strains of bird flu have been confirmed across Asia and in Europe. Authorities have culled millions of birds in affected areas to control the outbreaks.
France, which has the largest poultry flock in the European Union, has reported outbreaks of the highly contagious H5N8 bird flu virus. In South Korea, the rapid spread of the H5N6 strain of the virus has led to the country's worst-ever outbreak of bird flu.
(Reporting by Lewis Krauskopf in New York and Jo Winterbottom in Chicago; Editing by Will Dunham)