Date of Final Oral Examination (Defense)
Type of Culminating Activity
Master of Arts in Anthropology
Kristin Snopkowski, Ph.D.
Samantha Blatt, Ph.D.
John Ziker, Ph.D.
Leprosy, caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis, is a chronic, infectious disease that eventually causes disfiguring skin lesions, nerve damage, and muscle weakness. Even though leprosy has been nearly eliminated in many parts of the world today, it remains endemic in India, Myanmar, Nepal, Brazil, and a few African countries. Unfortunately, this infectious disease is not limited to just modern populations. In the past, leprosy spread globally and was a pervasive, degenerating disease. The literature traces leprosy back to 1550 BCE although there is possible skeletal evidence of leprosy in Rajasthan, India from 2000 BCE, suggesting it originated there and spread on a larger scale, but leprosy’s dissemination remains uncertain.
Presently, numerous scientific articles exist on the paleopathology of leprosy, but no meta-analysis of leprosy has ever been done. In this paper, a meta-analysis was conducted on 1,645 paleopathological cases of leprosy found in 102 sites ranging from 3125 BCE to 1905 CE. This meta-analysis statistically tested the prevalence of leprosy based on the paleopathological literature to chart the pathogen’s occurrence. First, a comprehensive search was conducted on previously published peer-reviewed literature to identify archaeological sites where leprosy was reported. These were geographically and temporally grouped together to trace the disease’s effect in the varying populations over time. Second, the null hypotheses that the frequency and distribution of bone lesions due to leprosy did not change through time were tested. Results suggest that the frequency and distribution of bone lesions did change over time, increasing in frequency in the Iron Ages and the Middle Ages, contrary to the null hypotheses.
Additionally, the average age at death of a leprosy sufferer rose almost 12 years from the Bronze Age to the Iron Age (26.6 years versus 38.3 years). Age at death remained relatively constant through the Middle Ages. There were more male skeletons than female skeletons (N = 312 versus N = 221) although females died at a younger age than males in all time periods analyzed except the Bronze Age.
This project suggests that Mycobacterium leprae originated in South Asia, slowly reaching Europe where it spread quickly and prospered for over 400 years, dramatically declined worldwide, and was eventually introduced to the New World likely through colonialism and the slave trade. Due to a rise in co-infection with other pathogens and improved social conditions, Europeans likely developed a natural resistance to leprosy. Leprosy’s current global situation is also discussed, with 1.15 million infected individuals as of 2013 (World Health Organization, 2016). This is the first meta-analysis examining leprosy’s global imprint in the archaeological record and provides evidence for how bone lesion frequency and distribution changed across time and space.
Schreier, Mallory Alexis, "The Impact of Mycobacterium leprae: A Comprehensive Meta-Analysis of the Paleopathological Literature" (2016). Boise State University Theses and Dissertations. 1091.