Researchers analyzed the DNA of 1,300-year-old skeletons in some medieval burials in Germany and found that infectious pathogens tormented a rural community.
In their study, titled "Pathogen Genomics Study of an Early Medieval Community in Germany Reveals Extensive Co-infections," published in the journal Genome Biology, researchers report a high prevalence of infection with various pathogens and showed how people before became susceptible to infection in times of climate change.
DNA Analysis Reveals People in the Medieval Period Suffered From Multiple Infections
Researchers isolated DNA from 70 human skeletons excavated within the borders of the early medieval settlement Lauchheim "Mittelhofen." According to Phys.org, the graves are dated to the late Merovingian period (7th-8th century CE) and could be associated with distinguishable farmsteads.
Research team leader Professor Ben Krause Kyora from the Institute for Clinical Molecular Biology of the CAU said that the DNA showed that the inhabitants of Lauchheim suffered from infections from various pathogens, like Mycobacterium leprae, the hepatitis B virus HBV, the parvovirus B19, and the variola virus VARV.
The infectious agents caused chronic and acute diseases of varying severity, like M. leprae developing into highly debilitating leprosy. More so, symptoms of HBV infection range from mild abdominal discomfort to liver fibrosis and liver cancer. Although B19 is usually asymptomatic and rarely causes severe complications, it caused high mortality before its eradication in 1980.
On the other hand, Professor Krause-Kyora said they could not tell of the symptoms of VARV in the medieval period due to the genetic differences between its modern and medieval versions.
The authors noted a substantial co-infection of two to three different infectious agents in the skeletons in which 31% in the medieval grave died with a molecular trace of infection with at least one pathogen. Dating of the medieval graves suggests that it was used for approximately one century for at least three to four generations.
They believe that their reports likely underestimate the true prevalence of infection in Lauchheim in the early medieval period. Krause-Kyora remarks that some infections may have become undetected, considering that all soft tissue deteriorated and only blood-borne pathogens can be reliably identified in the bones.
Poor Hygiene and Climate Change
The Middle Ages is commonly regarded as an age of lack of personal hygiene, disease-carrying rats, and genal unsanitary living conditions. The Lauchheim residents were in poor health, as evident in their skeletons, showing signs of infections and inadequate diet.
As LiveScience reported, Professor Almut Nebel from CAU's Institute of Molecular Biology, one of the study's senior authors, said that at that time, Europe experienced a rapid climate decline known as the Late Antique Little Ice Age, affecting crops that eventually led to famine.
Krause-Kyora explained that general climate deterioration during this time led to temperatures in the Northern Hemisphere cooling by about 3.6 degrees Fahrenheit (2 degrees Celsius) on average. It was a phase of a bad climate that led to the general weakening of the population due to crop failure.
It also increased their susceptibility to diseases that allowed diseases to jump from animals to humans and adapted to them as new hosts. Additionally, the diseases spread widely in new populations, which explains how pathogens became established in human populations, which led to large pandemic outbreaks after several centuries during the medieval period.
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