The Medievalist and the Microbiologist: How Plague and Leprosy Have Opened Up New Perspectives on the History of Health
Monica H. Green, Arizona State University
Plenary Lecture given on May 27, 2012 at the Canadian Society for the History of Medicine Annual Conference, University of Waterloo
Monica Green, known as “the foremost authority on medicine in the Middle Ages,” examines how her field has changed in recent years. In 2001, two genetic breakthroughs were made – the entire genomes for both plague (Yersinia pestis) and leprosy (Mycobacterium leprae) were sequenced.
Microbiology/genetic analyses have so far proven to be very beneficial at answering some questions, such as:
- What was the disease?
- How old is the disease?
- Where did it come from?
Paleopathology (the study of old bones) is a bigger factor in the determining the history of leprosy – this science is often not good at certain diseases, but for leprosy it is very good at finding lesions, such as at nasal cavity.
Our generic understanding of leprosy has allowed us to identify the oldest DNA in an individual, a skeleton from Uzbeckistan that is dated between 1st to 4th century AD. The disease’s organism is now thought to several million years old, and the organism has stopped evolving because it so comfortable in human populations.
But certain questions remain to be answered: How many were afflicted? How did people respond? Green notes one particular problem with ur understanding of leprosy: Why did it ‘suddenly’ become a social problem in Europe in the 11/12th century. She notes the research done by Jesper L. Boldsen on cemeteries in Denmark and Germany. In the article ‘Leprosy and mortality in the Medieval Danish village of Tirup‘, Boldsen found that nearly everybody was infected in a late medieval community.
Also, in his article ‘Outside St. Jørgen: Leprosy in the medieval Danish city of Odense‘ in the three non-leprosy cemeteries, they had leprosy too, but in the leprosy cemetery there would be people who were obviously infected in the face, suggesting that segration was a social practice. Meanwhile, a 2008 study of Lauchiem, small town in 5th-7th century Germany, found that 1 in 4 men had it, but only 1 in 50 women – what were men doing to make them more susceptible?
Historians can now conclude that leprosy did decline in the Late Midle Ages, first in the towns and cities, later in rual communities, because of institutionalization and use of leper hospitals. It also seems that leprosy was not a worry until 11th/12th c, but leprosy was around before that, and we now see it as much broader and widespread disease
Turning to plague, Green explains that we are unable to use paleopathology on it because people die too quickly, or recover and leave no skeletal signs of the disease. Microbiological research shows that the organism Yersinia pestis may be as young as 2000 years and it developed from Yersinia pseudotuberculosis, which caused chronic but mild symptoms.
Lester Little’s article, ‘Plague Historians in Lab Coats‘ talks about how a consensus has developed about the disease
and how microbiologists and scientists getting all the press these days, but there are problems with this. Green says historians need to fight back and “we need to be the ones to put in the human elements” for medical history.
Green is worried that interdisciplinary efforts – the discourse between scientists and historians – are not happening, and that the work being done by scientists may be undermined by their lack of proper examination of non-scientific resources, such as artistic evidence.
Green is now beginning a new course – Global History of Health – which looks at major changes in human disease patterns caused by changes in human culture. The course examines long standing changes in human history, such as the rise of agriculture and human migrations, and focuses on eight diseases, including smallpox, cholera and syphilis, which are global and possible to reconstruct the scientific evidence for it too.
Green concludes by noting that plague and leprosy are not just historical topics, but relevant in today’ world. Plague is still active among rodents in four inhabited continents, and it is still capable of human outbreaks, such as in 1994 when two plague epidemics struck western India. Meanwhile, leprosy is not yet under control around the world. While rates are coming down and people are treated, there was at least 166000 new cases in 2009 in south-east Asia.