32 • Keith Manchester 



proposition is correct, and more research is obviously neces- 

 sary, then the high Naestved presence of lepromatous disease 

 may not reflect the overall population immunological trend 

 in the Middle Ages. The leprous population not segregated 

 may have developed a shift, through time, toward the high- 

 resistant end of the immunological spectrum. In so doing, by 

 a reduction in the rate of bone involvement, the very evidence 

 necessary in paleopathology may be nonexistent. The further 

 hypothetical implication for infectivity in antiquity will be 

 explored. 



Interpretation 



Tuberculosis and leprosy are diseases which coexist in many 

 underdeveloped countries of the world today. Within the time 

 scale of modem epidemiological observation, there has been 

 little change in their natural prevalence, and there has not 

 been any comparative change in incidence rate, one disease 

 against the other. Analysis of tuberculosis and leprosy, sepa- 

 rate and intercurrent, in individuals has suggested that there 

 is no relationship between these two infectious diseases in 

 mankind (Chaudhuri and Ghosh 1975:302). The essentially 

 epidemiological research of these two workers examines the 

 disease status of patients at a specific time. The data do not. 

 and indeed cannot in the absence of a predetermined immune 

 status, identify to which pathogen, M. luherciilosis or M. 

 leprae, the host was first exposed. Contrary to earlier opin- 

 ion, it is now known that there is no increased susceptibility 

 in lepromatous leprosy to tuberculosis (Jopling 1982:305). 

 Tuberculosis has been, however, a major cause of death in 

 modem leprosaria. Although there are immunological im- 

 plications of this fact, the main reason for the high number of 

 tuberculous deaths in leprosaria probably lies in the environ- 

 ment with the facility for respiratory transmission of M. tu- 

 berculosis. 



While epidemiology examines these two diseases and the 

 changing pattems thereof through decades, paleoepidemiol- 

 ogy examines through centuries. Precision in epidemiology, 

 even with the constraints of Third World data, is obviously 

 greater than in paleopathology, and in archaic contexts can 

 never be complete. The multitude of environmental, social, 

 biological, and therapeutic factors that inlluenced changing 

 patterns of disease in antiquity can never be fully known. 

 There must, therefore, be an element of surmise and calcu- 

 lated guesswork in the interpretation of disease in antiquity. 



It is clear, as has been demonstrated (v.s.). that tuber- 

 culosis and leprosy coexisted, at least for many centuries, in 

 British antiquity. It is clear also that leprosy, as an endemic 

 disease, declined and disappeared in the high Middle Ages, 

 while tuberculosis continued unabated into modem times. 



Leprosy, as a di.sease of single mode of transmission, dem- 

 onstrates prevalence and incidence rates which are dependent 

 upon population density, intrapopulation contact, intimacy 

 of contact, and economic status. The increasing prevalence 



during the Anglo-Saxon period and, particularly, the early 

 Middle Ages, is due to increasing population, to increasing 

 population density, and to increasing contact between peo- 

 ples. As a natural disease per se, it is expected that the preva- 

 lence of the early Middle Ages would be maintained or even 

 increased during the later Middle Ages. This is demonstrated 

 to be not so. 



It is suggested that tuberculosis, a disease of animal and 

 human host, and a human disease of two modes of transmis- 

 sion, was a biphasic human disease. In the earlier phases of 

 tuberculosis history in Britain, it was a primary gastrointesti- 

 nal disease by M. bovis transmitted from infected cattle. In 

 the pre-urban era of low population density village society, 

 tuberculosis was a sporadic disease. Therefore, a significant 

 reservoir of immune, that is, tuberculin positive, population 

 did not exist. Ikwueke (1984:1357) proposes that a new dis- 

 ease in a community is relatively vimlent and tends to affect 

 young generations. It is likely therefore that, in this first 

 phase of development, many of the tuberculous individuals 

 with primary gastrointestinal disease died, thereby removing 

 them from the immune pool. 



It is further suggested that, with increasing population, 

 mobility of peoples, and urbanization, there was a biological 

 adaptation of the tubercle bacillus to a respiratory mode of 

 transmission. The increased population density, increased 

 contact between peoples, and, perhaps, reduced hygienic 

 standards, developing, pari passu, with urbanization, fa- 

 vored a widespread population exposure to M. tuberculosis. 

 In antiquity, just as today, primary tuberculous infection oc- 

 curred in young children. According to the concept of disease 

 aging in the community (Ikwueke 1984:1356). there is a 

 gradual decline in the severity of disease during its historic 

 presence in mankind. Therefore, although many young 

 children probably succumbed to the primary infection, many 

 more survived with their consequent acquired immunity, 

 manifest today by tuberculin sensitivity conversion . It is sug- 

 gested that the urbanized population during the advancing 

 Middle Ages became, in increasing numbers, immune to 

 tuberculosis. Although village inhabitants had gradually de- 

 veloping contacts among themselves and with urban dwellers 

 through market trading, the increasing incidence of tuber- 

 culosis may have been slight relative to the urban com- 

 munity. There may also have been a higher proportion of M. 

 bovis infection relative to M. tuberculosis in the village, but 

 this is of no significance in individual tuberculous immunity. 



How far then may the coexistent developments of tuber- 

 culosis and leprosy in the medieval period in Britain be seen 

 as independent entities, and how far may they be considered 

 to demonstrate an interaction of infectious disease according 

 to modem immunological concepts? 



INDEPENDENT CHANGE 



Similarities of bacterial form and properties of M. tuber- 

 culosis and M. leprae have been discussed. The respiratory 



Zagreb Pateopaihology Symp. 1988 



