In 1855, near the height of a devastating worldwide epidemic, cholera killed an estimated 27,000 people in the northern Italian province of Tuscany. Relatives of cholera victims in the Tuscan village of Badia Pozzeveri, near Lucca, buried their loved ones in a special area of the cemetery adjoining a local church. Now, a team of archaeologists and other researchers are excavating the remains in the hopes of finding DNA belonging to the bacteria that causes cholera—a crucial key to better understanding the disease and how to prevent it.
Caused by the bacterium Vibrio cholerae (V. cholerae), the disease known as cholera invades the small intestine, causing severe diarrhea and dehydration; in the most extreme cases, it can kill its victims within hours. Beginning in the early 19th century, cholera spread from its origins in India throughout the world in a series of devastating global epidemics. During the third cholera pandemic in the 1850s, the English doctor John Snow made a major breakthrough in the study of the disease when he traced one outbreak in London to a contaminated water pump in the Soho district.
Despite increased knowledge of the disease over the past two centuries, cholera still kills people today. The World Health Organization recorded more than 100,000 cases of cholera in 2013, while periodic epidemics can result in a much higher number of cases. An outbreak that followed the devastating earthquake in Haiti in 2010, for example, pushed the number of cholera cases worldwide in 2011 to 600,000.
Now, a team of archaeologists and other scientists hope that the cemetery of an abandoned church in Tuscany will yield the next great clue to understanding—and fighting—cholera. At San Pietro Pozzeveri, located in the village of Badia Pozzeveri, victims of the 1850s cholera epidemic were hastily buried in a special section of the church graveyard, their bodies encased in lime to prevent the spread of the disease. For the past four years, the team led by Clark Spencer Larsen, an anthropology professor at Ohio State University, has been excavating the bodies buried in the cholera section of San Pietro’s cemetery. They found that the lime had hardened like concrete around the bodies, inadvertently preserving the remains along with the soil around them—soil that may hold human DNA as well as DNA from the bacteria and organisms that lived inside them.
This past weekend, Larsen discussed the project—a joint venture between OSU and the University of Pisa—at the annual meeting of the American Association for the Advancement of Science in San Jose, California. “To our knowledge, these are the best preserved remains of cholera victims of this time period ever found,” he said in a statement put out by the university. “We’re very excited about what we may be able to learn.”
In particular, Larsen and his colleagues hope to find traces of DNA belonging to V. cholerae, the bacterium that causes cholera. According to Larsen, they haven’t found it yet, but they have found preserved human DNA, as well as DNA linked to other types of human disease. The researchers plan to continue searching, and remain hopeful that they may eventually locate DNA of the cholera-causing pathogen.
In addition to the potential windfall of insight into cholera, San Pietro’s cemetery represents a treasure trove of information about the lives and deaths of the people buried there over the past 1,000 years. Between 1056 and 1408, the site was home to a monastery; after it was abandoned, the church founded there remained open until about 50 years ago. The church particularly thrived during in the Middle Ages, in part for its proximity to the Via Francigena, or “Road From France,” the route traveled by many traders and pilgrims to England’s Canterbury Cathedral.
Several cemeteries surround the site and contain remains dating to different centuries, including the 14th-century victims of the infamous Black Death (bubonic plague). As Larsen puts it: “We have a thousand-year window into the health of this village…It is a microcosm of what is happening in Italy and all of Europe during this time frame.”