The Pueblo City-County Health Department confirmed an adult died from the plague in the southern part of Colorado Wednesday, making him or her the second victim of the plague that hit Colorado this year.

The local health department believes that the victim, who remains unnamed, may have contracted the disease when he or she was bitten by a flea that carried the blood of a dead rodent or other animal, according to NBC's Colorado affiliate 9 News.

The first incident occurred in June when a 16-year-old boy from northern Colorado died from the plague, which he was not diagnosed with until he had died.

Both are believed to have died from septicemic plague, a rare and deadly form of the disease that killed millions during the Middle Ages, according to the Washington Post. Now, only seven plague cases are reported in the U.S. each year, with most of them easily being treatable with modern medicine.

As reported by the Centers for Disease Control And Prevention, the plague is caused by the bacterium Yersinia pestis. Humans can become infected after they are bitten by an animal carrying the bacterium or by handling an infected animal.

The local health department notes the only animals confirmed with plague so far this year in Pueblo County were in an area of Turkey Creek near the county's western edge.

The department also notes that those infected don't show symptoms until two to six days after they contract the disease.

Sarah Joseph, public information officer for the Pueblo City-County Health Department, says the Pueblo City-County Health Department is now working to inform the public on ways to avoid infection.

"The main thing the health department is doing is letting the public know to protect themselves and their pets from fleas that carry the disease. Today and tomorrow public health staff will put up signs in the affected area," she said.

"The key to treating the plague is catching it in time. Patients have to get treatment in a timely manner, and physicians have to identify the plague in time," she concluded.