People could contract plague that is now infecting prairie dog towns in South Dakota, although the disease is rare and treatable, according to Lon Kightlinger, state epidemiologist with the South Dakota Health Department.

Plague had not been confirmed for decades in South Dakota prairie dog towns, although it had decimated prairie dog populations in eastern Wyoming in recent years.

Then plague was confirmed in one prairie dog three years ago in extreme southwestern Custer County, near Wyoming. In 2005, plague wiped out thousands of prairie dogs in a large colony north of Oglala on the Pine Ridge Indian Reservation.

Oglala Sioux Tribe and Indian Health Service officials launched a public-education campaign to reduce the threat to people who live near prairie dog towns that have been affected.

No one on the reservation has gotten the plague so far, according to Trudy Ecoffey, a senior biologist with the Oglala Sioux Tribe Parks and Recreation Department. Ecoffey is monitoring the spread of plague in prairie dog colonies on the reservation.

She also said crews have sprayed insecticide to kill fleas in housing areas near prairie dog towns hit by plague. Fleas are the primary carriers of plague.

Although there are human cases of plague in the U.S. every year, no one in South Dakota has been reported with plague, Kightlinger said.

He said humans can get the plague indirectly, usually through pets that get infected by fleas. Animals that eat prairie dogs killed by plague can also contract plague, wildlife experts say.

"What often happens is a pet, like a dog or a cat, gets infected," Kightlinger said. "Then the dog or cat brings it back, and people get infected."

Cats, particularly, will cough if they get the plague and will transmit the disease to humans that way.

Kightlinger said in animals such as prairie dogs and other rodents, plague is called sylvatic plague.

In humans, the plague is either bubonic or pneumonic.

Pneumonic plague attacks the respiratory system.

Bubonic plague, although very serious, is very rare, Kightlinger said. It is marked by "rising pustules" and infection of the lymph nodes, particularly in the crotch. Without treatment, bubonic plague kills up to half its victims, he said.

Bubonic plague, known as the Black Death, killed millions of people in Europe and Asia in the Middle Ages.

But both types of plague in humans are treatable with antibiotics if detected early, Kightlinger said.

Last year, there were 17 cases of plague in humans, primarily in the Four Corners area of Colorado, Utah, New Mexico and Arizona.

Since plague was discovered in the prairie dog complex north of Oglala in 2005, Oglala Sioux Tribe officials have launched public-education campaigns, advised residents to get flea collars for pets and provided funds to spray for fleas.