PROCEEDINGS OF THE LATVIAN ACADEMY OF SCIENCES. Section B, Vol. 71 (2017), No. 1/2 (706/707), pp. 1–7. DOI: 10.1515/prolas-2017-0001 PALAEOPATHOLOGICAL EVIDENCE OF INFECTIOUS DISEASE IN A SKELETAL POPULATION FROM LATE MEDIEVAL RIGA, LATVIA (15TH-17TH CENTURIES AD) Guntis Gerhards1,#, Elîna Pçtersone–Gordina1, and Zita Krûmiòa2 1 Institute of Latvian History, University of Latvia, Kalpaka bulv. 4, Riga, LV-1050, LATVIA 2 Latvian Biomedical Research and Study Centre, Râtsupîtes iela 1, Riga, LV-1067, LATVIA # Corresponding author; [email protected] Communicated by Jânis Kloviòð The aim of this study was to evaluate the presence of infectious disease in the Dome Church (Riga Cathedral) Cemetery population, dating from the late medieval period (15th–17th centuries AD). A total of 274 individuals were macroscopically observed for evidence of infectious disease, and seven individuals with lesions possibly associated with a bacterial infection affecting the skeleton were selected for further analysis. Pathological changes on the outer table of the skull and in the long bones of legs characteristic of venereal syphilis were observed in four female and one male individual. Likewise, changes possibly related to late congenital syphilis were observed in a 14–15-year-old non-adult individual. All these individuals were buried in a small area adjacent to the northern wall of the Dome Church, which possibly belonged to a hospital or a shelter. The evidence for venereal syphilis from the cemetery complements historical data about the spread of the disease in Riga during the 16th–17th centuries AD. One adult male individual had destructive changes in the lower spine, which could be associated with tuberculosis (TB). So far, this is the first individual with possible TB from the archaeological populations of Riga. This research pro- vides unique evidence about infectious disease in skeletal populations from the late medieval pe- riod in Latvia, and the results will be used as the basis for future research in the subject, including extraction of ancient pathogen DNA. Key words: palaeopathology, infectious disease, tuberculosis, venereal syphilis. tory of epidemics is not only important for understanding INTRODUCTION the life and death in past populations; learning about the spread and the course of infectious diseases in the past can Infectious diseases were responsible for a substantial help to prevent and limit them in living populations. Many number of deaths in the past populations, especially in over- of these diseases have not disappeared and still affect peo- st crowded urban environments (Larsen, 1997). Indeed, mor- ple around the world, regardless of the advances of the 21 tality rates of the living populations only significantly de- century medicine, with the same consequences as in antiq- creased in the 20th century, when the overall quality of life uity. improved thanks to better nutrition and hygiene, as well as the invention of antibiotics and vaccines (Cronberg, 1986). The quality and quantity of palaeopathological data depends Although historical sources can provide an insight into the on a variety of factors, such as funeral practices, the quality quality of life, morbidity and mortality in the past popula- and strategy of archaeological excavations, the preservation tions, the primary source of information is palaeopathologi- of skeletal remains in different soil conditions, as well as cal analysis of archaeological skeletal remains. the processes of bone diagenesis in the ground. Often, the limiting factor in a thorough palaeopathological analysis is The aim of this paper is to present data about infectious dis- fragmentary or poorly preserved skeletal remains. When eases in Riga during the late medieval period, based on dealing with historical populations, historical sources such skeletal material from the Riga Dome Church Cemetery. as documents describing certain historic events, diseases Such specific research has not been attempted before, and and epidemics, medical prescriptions, iconography, as well therefore the results will provide unique evidence about in- as data from archaeological excavations and ethnographic fectious disease in Riga during the period in question, as data can provide a valuable secondary source of informa- well as form a basis for further research. Studying the his- tion, the primary source being actual skeletal remains (Rob- Proc. Latvian Acad. Sci., Section B, Vol. 71 (2017), No. 1/2. 1 erts, 2002). Unfortunately, there is a lack of information that the disease is often mentioned in historical sources about years of bad harvests, famines and epidemics in the (Bergmann, 1888), along with specialised leprosy hospitals written sources from late medieval Latvia. Moreover, in the or leprosaria, the first of which was mentioned in 1225, so existing chronicles, every epidemic that caused high mortal- far no cases of leprosy have been found in the archaeologi- ity among the population was described as the plague, cal populations of Rîga. This could be due to the strategy of which was not always the case (Dunsdorfs, 1962). For a most archaeological excavations, when skeletal material better understanding about outbreaks of infectious disease was not collected completely, leaving smaller bones such as in the past, it is important to consider the historical context, those in hands and feet, behind in the excavation trench. including the circumstances that could have caused or en- Bone changes specific to leprosy can affect hands and feet couraged the spread of the disease. Listed below are just a (Ortner, 2003), but they are simply not observable in indi- few preconditions that could have helped the spread of in- viduals that have not been fully collected. With regards to fectious disease in medieval and late medieval Riga. the skeletal population analysed during this research, how- th ever, most bones of hands and feet were available for analy- Since the very beginning of its foundation in the 13 cen- sis. tury, Riga was built as an enclosed city, with a high popula- tion density inside the city walls (Ðterns, 1997). Occasion- Venereal syphilis (VS) is caused by the bacterium ally, during disasters such as famines and wars, the city had Treponema palladium palladium and it can affect the skele- to accommodate a large number of immigrants, and the ton in the third stage of the disease after onset, but only in overcrowded conditions increased the possibility of epidem- 20% of those affected. In the majority of cases, the skull ics. Infectious diseases spread with the speed of their carri- and the long bones of legs are involved (Steinbock, 1976). ers. In the past, the diseases were carried via trade routes, In Riga, skeletal changes possibly caused by VS have been ports, and by marching armies. In the medieval period Riga found in the skulls of two individuals from the Dome was often involved in territorial disputes, which brought Church (Derums, 1988). In a wider context, evidence for foreign armies into its territory. On the other hand, since the VS in the late medieval period in Latvia has also been found city was among the largest trading centres on the Baltic in skeletal populations from Dobele (Jankauskas, 1994) and coast, it attracted traders and buyers from all over the re- Ventspils (Gerhards, 2005). gion. As a result, the inhabitants of Riga were at high risk of contracting various diseases. According to historical Tuberculosis (TB) is an infectious disease caused by myco- sources, there was a number of infectious diseases affecting bacteria, particularly Mycobacterium tuberculosis. TB only the population of Riga during the late medieval period, in- involves the skeleton in 5% of all affected individuals dur- cluding typhus, plague, and smallpox (Brennsohn, 1905). ing the active stage of the disease. Usually the changes af- Combined with poor nutrition and low quality of life, the fect the spine, as well as ribs and joints (Ortner, 2003). So diseases greatly reduced the life expectation of the popula- far, there is no data about TB in the medieval populations of tion (Zariòa, 2009). Riga. Only a small number of individuals with skeletal changes possibly related to TB have been reported in Lat- Since the majority of infectious diseases only affect the soft vian skeletal populations so far (Derums, 1988). tissue, they are hard to trace in skeletal remains. If, how- ever, the disease has become chronic, instead of causing death shortly after onset, there is a possibility to detect it in MATERIAL AND METHODS the skeleton. Nevertheless, when finding possible infec- In and around the Riga Dome Church, three burial grounds tion-related bone changes in skeletal remains it is often dif- dating from the medieval and late medieval period were dis- ficult to name the cause. This is because the bone response covered during archaeological excavations, the first inside to infection is limited and therefore the changes look similar the church, the second in the courtyard and the cloisters, in a number of conditions. One of the most typical bone re- and the third outside the church. In this study, 274 individu- sponses to soft tissue infection is deposition of new bone on als recovered in 1986–1989 from the third burial ground top of existing bone surface (periosteal new bone forma- outside the church, were analysed. During the excavations, tion). Such changes, if affecting the skeleton without a par- the area was already a part of the Dome Square, with no ev- ticular pattern, are called non-specific. There are, however, idence of burials, such as gravestones, above the ground. chronic infectious diseases to which the human skeleton re- The oldest part of the cemetery was to the east of the sponds in a particular way, and they are therefore recognis- church, but the most recent was located by its northern wall. able during palaeopathological analysis. These diseases in- Apart from individual graves, several collective burials clude leprosy, venereal syphilis, and tuberculosis (TB) were also uncovered in the most recent part of the cemetery (Ortner, 2003).