An ancient graveyard in Italy can yield clues about the evolution of deadly bacterium that causes cholera, researchers believe.

The researchers are excavating the graveyard surrounding the abandoned Badia Pozzeveri church in the Tuscany region of Italy.

The site contains victims of the cholera epidemic that swept the world in the 1850s.

"We have a thousand-year window into the health of this village. It is a microcosm of what is happening in Italy and entire Europe during this time frame," said Clark Spencer Larsen, a professor of anthropology at the Ohio State University.

Archaeologists have been excavating remains since the last four years in a special section of the cemetery used for cholera victims.

Finding traces of the pathogen that caused cholera among the human remains revealed details about how people lived - and died - in this region of Europe.

"To our knowledge, these are the best preserved remains of cholera victims ever found in this time period," said Larsen, one of the leaders of the excavation team.

"We're very excited about what we may be able to learn," he said.

The bodies of the cholera victims were hastily buried and covered in lime, that hardened like concrete around the bodies. Researchers suspect residents were trying to prevent the disease from spreading.

The lime trapped soil around the bodies that contained the ancient DNA of bacteria and other organisms that lived in the humans buried there.

"We haven't found it yet, but we are hopeful that we will. We've found other DNA associated with humans, so we're continuing with the search," said Larsen.

"If we find the DNA, we could see how cholera has evolved and then compare it to what the bacteria is like today. That's possibly the first step to finding a cure," the researcher explained.