Molecular analysis of skeletal tuberculosis in an ancient Egyptian population

A paleomicrobiological study was performed on 37 skeletal tissue specimens from cadavers in the necropolis of Thebes-West, Upper Egypt, (2120-500 BC) and four from the necropolis of Abydos (3000 BC). The subjects had typical macromorphological evidence of osseous tuberculosis (n = 3), morphological alterations that were not specific, but probably resulted from tuberculosis (n = 17), or were without morphological osseous changes (n = 21). DNA was extracted from these bone samples and amplified by PCR with a primer pair that recognised the Mycobacterium tuberculosis complex insertion sequence IS6110. To confirm specificity of the analysis, the amplification products of several samples were subjected to restriction enzyme digestion, or direct sequencing, or both. In 30 of the 41 cases analysed, ancient DNA was demonstrated by amplification by the presence of the human beta-actin or the amelogenin gene and nine of these cases were positive for M. tuberculosis DNA. The results were confirmed by restriction endonuclease digestion and sequencing. A positive result for M. tuberculosis DNA was seen in two of the three cases with typical morphological signs of tuberculosis and amplifiable DNA, in five of 13 non-specific, but probable cases (including two cases from c. 3000 BC), but also in two of 14 cases without pathological bone changes. These observations confirm that tuberculosis may be diagnosed unequivocally in skeletal material from ancient Egypt, even dating back to c. 3000 BC. As a positive molecular reaction was observed in most of the typical cases of skeletal tuberculosis, in about one-third of non-specific, but probable tuberculous osseous changes and, surprisingly, in about one-seventh of unremarkable samples, this suggests that infection with M. tuberculosis was relatively frequent in ancient Egypt.