St Leonard Catholic Church in Machnung-Pichl, near Ingolstadt Bavaria, Germany held a secret for many years. Renovations to the church back in 1984 found a mass burial site under the sacristy, 75 human skeletons stacked like lasagna in four layers with a little dirt between each layer (Wiechmann, Harbeck, & Grupe, 2010). The design of the site is a little unclear. They say it was not a dug pit and that it can only be dated to 1200 to 1500 CE by the Gothic design of surrounding building structures. From this I conclude that it was some kind of crypt, even if the structure wasn’t originally intended to be a crypt. I don’t understand why the skeletons couldn’t be carbon dated but it apparently wasn’t done. Without more precise dates, we can’t be sure that all of the bodies were deposited over a short period.
Wiechmann, Harbeck and Grupe (2010) were interested in these skeletons as possible plague victims. Out of the 33 skeletons examined, Yersinia pestis DNA was detected in 10 individuals. A 30% positive result for aDNA testing of a site is I think as high has I’ve read before. Six positive skeletons were selected for further study with an additional four primer pairs for the Y. pestis plasmid pPCP1, including testing for the plasminogen activator and pesticin (a bacteriocin). All of the new markers were detected for at least one skeleton. From this data they conclude that the skeletons found in the mass grave represented plague victims.
Tran, Raoult, & Drancourt (2011) sent a letter to the editor to appear in the May issue of Emerging Infectious Diseases to contest a claim that Wiechman, Harbeck and Grupe didn’t make! The original letter describing these findings made no claim for which biovar of Yersinia pestis is present (Wiechmann, Harbeck, & Grupe, 2010 & 2011). Tran, Raoult and Drancourt (2011) appear to be anticipating that they will find that this strain does not belong to the oreintalis biovar, which would conflict with their previous assertions that all medieval Y. pestis they have found belong to the orientalis biovar. The wrangling over the biovars and lineages of medieval Yersinia pestis is just beginning.
Historically what matters is that 75 people, mostly victims of Yersinia pestis, were buried beneath the Church of St Leonard in the Late Middle Ages. Of the six people tested by Wiechmann, Harbeck and Grupe (2010), there were 2 females and 4 males between ages of 8 and about 25. They were not clergy. If this is a representative selection of individuals, they probably were not high status townspeople based on their ages. The lineage of their Yersinia pestis is not the only unsolved mystery about these people left to be solved.
Wiechmann I, Harbeck M, & Grupe G (2010). Yersinia pestis DNA sequences in late medieval skeletal finds, Bavaria. Emerging infectious diseases, 16 (11), 1806-7 PMID: 21029555
Tran T-N-N, Raoult D, Drancourt M. Yersinia pestis DNA sequences in late medieval skeletal finds, Bavaria [letter]. Emerg Infect Dis [serial on the Internet]. 2011 May [cited April 2011]. http://www.cdc.gov/EID/content/17/5/955.htm DOI: 10.3201/eid1705.101777
Wiechmann I, Harbeck M, Grupe G. Yersinia pestis DNA sequences in late medieval skeletal finds, Bavaria [letter]. Emerg Infect Dis [serial on the Internet]. 2011 May [cited April 2011]. http://www.cdc.gov/EID/content/17/5/955.htm DOI: 10.3201/eid1705.102013