Barbara Bramanti looks for remnants of old plague bacteria in a plague victim from Florence who died during the Justinian Plague in the mid-500s AD. Credit: Photo: Dr Elsa Pacciani

Remnants of the genetic makeup of plague bacteria have been found in the teeth of victims of the Black Death and the major plague epidemics at the end of the Iron Age.

Italian researcher Barbara Bramanti (pictured) of the Centre for Ecological and Evolutionary Synthesis (CEES) at the University of Oslo is studying the evolutionary development of the plague bacteria and comparing the genetic code of the plague bacteria during the first two pandemics. The first major pandemic was the Justinian Plague at the end of the Iron Age, which lasted for 200years. The next apocalypse was the Black Death, a pandemic that kept coming in new waves, and lasted for 400 years.

The lymph nodes of the plague victims swelled up and transformed into black boils, where the bacteria would multiply. In many of the victims, the plague bacteria entered the bloodstream, and thus the dental pulp. Together with archaeologists, Dr Bramanti is collecting DNA samples from the teeth of 2,700 plague victims from Europe and Asia. She will also be checking the teeth of Norwegian victims.

Today there are 2,000 cases of plague annually; most of them in Madagascar and Congo. It also occurs in the deserts of North America and in large areas in Central Asia, in a wide belt from Georgia via Kazakhstan to China.

Biologists at the University of Oslo are making a giant effort to identify the relationship between climate change, rat infestations, and the many major plague epidemics throughout history, which may help predict the next plague outbreak.