The Marseille plague group has been suggesting for some time now that human lice could be a major vector of medieval plague. To test their hypothesis the group devised a multiplex PCR screening method to rapidly screen many aDNA samples for seven pathogens that could cause medieval epidemics, including relapsing fever and trench fever transmitted by human lice. Their method was previously published for a screening of mass burials from medieval Venice (Tran et al, 2011b).
In their most recent publication, they have examined 14 teeth from five skeletons found in Bondy, near Paris, France (Tran et al, 2011a). The remains are from people of varied ages and both genders, radiocarbon dated to the 14th century (1297-1373 with 70% probability). They were also screened for the pathogens that cause anthrax, trench fever, relapsing fever, typhus, typhoid fever, smallpox and plague. As in Venice, they only found two of these, trench fever (Bartonella quintana) and plague (Yersinia pestis) (Tran et al, 2011a; Tran et al, 2011b). Overall, B. quintana was found in three individuals and Y. pestis in two individuals, with one individual (#73, far left skeleton half revealed in the picture) positive for both. Trench fever is transmitted by the human louse and Tran et al (2011a) see this as supporting their hypothesis that lice transmitted the plague as well. While one unfortunate co-infected individual is not proof, it does add one more piece of evidence to support their hypothesis. Plague was confirmed by sequencing and identified as the orientalis biovar. This group has previously asserted that the orientalis biovar is transmitted much more efficiently by lice than other Y. pestis biovars (Avyadurai et al, 2010).
They are citing one more paper as ‘in press’ in Tran et al, 2011a. It looks like there is a summary paper coming up that will lay out all their arguments for lice as transmitters of medieval plague, so stay tuned!
Tran TN, Forestier CL, Drancourt M, Raoult D, & Aboudharam G (2011a). Brief communication: Co-detection of Bartonella quintana and Yersinia pestis in an 11th-15th burial site in Bondy, France. American journal of physical anthropology PMID: 21541920
Tran TN, Signoli M, Fozzati L, Aboudharam G, Raoult D, & Drancourt M (2011b). High throughput, multiplexed pathogen detection authenticates plague waves in medieval Venice, Italy. PloS one, 6 (3) PMID: 21423736
Ayyadurai S, Sebbane F, Raoult D, & Drancourt M (2010). Body lice, yersinia pestis orientalis, and black death. Emerging infectious diseases, 16 (5), 892-3 PMID: 20409400