Palaeopathology in the Osteological Collection of Anthropological Museum in Padova University: the cases of tuberculosis

Many evidence confirm that tuberculosis (TB) has been a constant disease of man throughout all his history. Moreover, till now it is one of the most important and dangerous diseases that are presently undergoing re-emergence: each year the number of new cases and the appearance of multiresistant tubercle bacilli are constantly increasing. Although human TB, principally caused by two members (M. bovis and M. tuberculosis) of the pathogenic Mycobacterium tuberculosis complex, is primarily the involvement a soft tissue infection, clinical data show skeletal involvement: for extrapulmonary TB, the rates for all osseous changes range from 1% to 9% (data from various authors reported by Santos, 2001), in the pre-antibiotic era the incidence of skeletal involvement is calculated in average 5-7% (Steinbock, 1976). The characteristic bone alterations in tuberculosis are the consequence of the development of granulation tissue, with a specific tropism for the richly vascularized sites. The diagnosis of TB in archeological human remains relies on the analysis of disease expression: lesion morphology, location and skeletal pattern. The skeletal alterations that actually are connected with tuberculosis can be gathered in “classical TB alterations” and in “MOLAT’, (“Minor Osseous Lesions Attributable to Tuberculosis”). The first group consists of characteristic alterations for which there are several clinical and paleopathological literature and osteological collections as referred: they represent TB skeletal changes already in developed stage. The second group of lesions (MOLAT) analyzes the early stages of disease to identify some diagnostic criteria to recognize it, and they don’t have the general consensus of all authors. In particular, the MOLAT characteristics are periosteal appositions on the visceral surface of ribs, endocranial changes, hypervascularization of vertebrae and hypertrophic osteoarthropaty. The present work studies a small osteological collection (Tedeschi Osteological Collection, T.O.C, of University of Padova, Italy), which was collected with didactical purposes in the years from the end of 19th century to the early 20th century in which cause of death, age at death and job are registered. This collection could be a potential source of information, but it was unknown till now. The aim of the present study is to recover this collection analyzing the TB remains looking for the classical alterations and the MOLAT. Using classical morphological anthropology, histology, radiology, molecular biology and densitometry of bone tissue, we try to confirm the various diagnostic criteria. Furthermore, this work, based on data arising before antibiotics became available for treatment, might contribute to the future diagnosis of TB or other pathologies in non-documented skeletal material. We have organized a work schedule with different exams to carry out in each individual recovered. This work form includes several aspects: individualization of remains, morphological study of diseases, histological and molecular analyses, bone density determination, and radiological exams. The individualization of remains, concerning sex, age, state of preservation and type of bone, was processed in all remains with the method of classical anthropology. Morphological study of diseases was the following stage of search. The pathological conditions were observed in the bones, looking at osseous diseases and particular infectious conditions. Histological analyses are processed in several cases. The osteological remains had been boiled and collocated in an unsuitable place and used for uncontrolled proposes: the thaphonomic processes occurred were unclear and extremely difficult to define. Six samples, randomly selected, were processed searching for DNA traits of Mycobacteria, although as remembered, the osteological collection was used by different researchers during these years and the perfect idea of a “virgin bone”, as many authors crave, is very distant to our sample situation. The densitometer is provided with a data base that allows comparison of the measured bone mineral content of an individual with that of a referral population. The data base of instrument was generated in vivo from healthy patients of both sexes. The machine used is called MatriScan, with a test totally not invasive, extremely quick and no special arrangements or training are required. Unfortunately, this is the first time that this new technique is used on osteological remains, thus similar data are not available to compare the results. Finally, the X-ray imaging is used in few ambiguous singular cases. During this research, for the first time T.O.C. was ordered and analyzed with traditional and modern techniques, about 60 individual forms have been completed and presented. Some characteristic TB evidences, that are part of MOLAT, have been studied for their diagnostic value. Our results could support the idea that vertebral hypervascularization is caused by TB disease: in T.O.C. sample it is associated with other typical TB evidences and it has been found in 53% of total spines and in 63% of spines with pathological evidences. In T.O.C. samples, only 31% of individuals recovered with ribs show periostitis. This result can not support the sure evidence that periostitis is caused by TB, according to Pfeiffer (1991) who claimed that it could rather be interpreted as a non-specific indicator of chronic respiratory disease stress. The histological analyses emphasized several unknown aspects concerning histology of ancient remains, i.e. the remodelling shown with haematoxylin- eosin and tricromic stain technique. The molecular tests demonstrate the presence of mycobacterium on the osteological samples analyzed, although they were partial and limited as state before. Densitometry with the new technique of MetriScan appears a potential instrument for further investigations. Many considerations were formulated to create the basis for further and deepened investigations not only to study TB individuals, but also to amplify the study with other skeletal pathologies described as causes of death (i.e. syphilis). In particular, molecular and morphological analyses should be furtherly considered.