Molecular Palaeopathology : Ancient DNA analyses of the bacterial diseases tuberculosis and leprosy

Abstract: This thesis “Molecular Palaeopathology. Ancient DNA analyses of the bacterial diseases tuberculosis and leprosy” deals with molecular palaeopathology, i.e. in this case the use of molecular methods to analyse ancient bacterial DNA in order to get further knowledge of diseases in ancient times. The analyses were performed on archaeological bone material and a calcified pleura from various, mainly Scandinavian sites, and the target was ancient bacterial DNA, specifically DNA-sequences within the bacterial genomes of the micro-organisms that cause tuberculosis (TB) and leprosy. The presence of tuberculosis is discussed in relation to various contexts and periods of time, i.e. in the Neolithic passage grave of Rössberga in central Sweden, the rural environment in the northern Swedish, Viking-Early Medieval site of Björned, the urban environment of the now southern Swedish city of Lund where the medieval churchyard of Trinitatis was situated, the city of Jönköping, Sweden, in the 14–16th century, and the Swedish man-of-war Kronan that sank in the Baltic Sea in 1676. It was possible to find ancient Mycobacterium tuberculosis complex DNA in a calcified pleura (Jönköping), in skeletal material that showed no morphological indications of tuberculosis (Kronan) as well as in material that showed morphological indications of the disease. Leprosy is discussed in relation to Björned and international archaeological sites, i.e. Püspökladény, Szombathely and Székesfehérvár in Hungary (10th–16th cent. AD), Shroud Cave in the Hinnom Valley, Israel (1st cent. AD), and the Dakhleh Oasis, Egypt (4th cent. AD). A coinfection of both tuberculosis and leprosy was found in several individuals from these sites and a possible explanation is given for this. This thesis also includes a discussion of the subject of palaeopathology and a brief research history of the area of ancient DNA/RNA analyses. Especially the bacterial diseases tuberculosis, leprosy and plague are discussed when it comes to their presence in ancient times, and what we have learned so far of them in antiquity, through the use of molecular palaeopathology. Small sections on syphilis and diphtheria, as well as chapters on parasites and viruses in past time periods are included and the problem of contamination in ancient DNA/RNA work is discussed. The presence of diseases in connection with animals, and especially whether there is a potential danger of excavating dormant dangerous pathogens are also discussed. It is concluded that ancient animal bones should be analysed as well as ancient human material when possible and relevant, since humans and animals may exchange various diseases/infections with each other. It is also concluded that there may be a small danger of acquiring diseases if bacteria that can produce spores are being excavated, but nevertheless this risk is very small. Future possibilities and questions in relation to molecular palaeopathology are also discussed.