BOZEMAN, Mont. -- A section of road that runs through Ted Turner's Flying D Ranch has been closed at the request of the Montana Department of Livestock after an outbreak of naturally occurring anthrax killed about 80 of the media mogul's domestic bison.

Steve Merritt with the livestock department said Monday that there is minimal risk to animals or people outside the closed area.

"We feel that it's really well confined," he said, adding that the soil on Turner's ranch is being disinfected to kill the bacteria.

Marna Daley, a spokeswoman for the Gallatin National Forest, said the nine-mile stretch of Spanish Creek Road would remain off limits for at least a week.

WIKI PAGE: Ted Turner's Bio

Anthrax is caused by a naturally occurring bacteria, Bacillus anthracis, which can lie dormant in the soil for decades. It can become active when heavy rains follow drought.

Animals are exposed to the disease by grazing or consuming forage or water contaminated with the spores. Untreated animals may die within 24 to 48 hours of exposure.

Anthrax can be spread from animals to people, but the state has not had a reported case of human anthrax since 1961.

State Veterinarian Marty Zaluski said last week that laboratory tests confirmed the anthrax in Turner's bison.

Turner is the founder of CNN based in Atlanta. He was raised in Savannah.