Earliest known human TB found in 9000-year-old skeletons
The discovery of the earliest known cases of human tuberculosis (TB) in bones found submerged off the coast of Israel shows that the disease is 3000 years older than previously thought. Direct examination of this ancient DNA confirms the latest theory that bovine TB evolved later than human TB. The new research sheds light on how the TB bacterium has evolved over the millennia and increases our understanding of how it may change in the future.
The bones, thought to be of a mother and baby, were excavated from Alit-Yam, a 9000 year-old Neolithic village, which has been submerged off the coast of Haifa, Israel for thousands of years. Scientists found characteristic bone lesions that are signs of TB in skeletons from the settlement, one of the earliest with evidence of domesticated cattle. An international team conducted detailed analyses of the bones using scientific techniques that revealed DNA and cell wall lipids from Mycobacterium tuberculosis, the principal agent of human TB. The DNA was sufficiently well-preserved for molecular typing to be carried out and the analysis of the bacterial cell wall lipids by high performance liquid chromatography provided direct, confirmatory evidence of tuberculosis.
This is the best evidence yet that in a community with domesticated animals but before dairying, the infecting strain was actually a human pathogen. The presence of large numbers of animal bones shows that animals were an important food source, and this probably led to an increase in the human population that helped the TB to be maintained and spread. The DNA of the strain of TB in these skeletons had lost a particular piece of DNA which is characteristic of a common family of strains present in the world today. The fact that this deletion had occurred 9000 years ago gives us a much better idea of the rate of change of the bacterium over time, and indicates an extremely long association with humans.
Examining ancient human remains for the markers of TB is very important because it helps to aid our understanding of prehistoric tuberculosis and how it evolved. This then helps us improve our understanding of modern TB and how we might develop more effective treatments.
Detection and Molecular Characterization of 9000-Year-Old Mycobacterium tuberculosis from a Neolithic Settlement in the Eastern Mediterranean. PLoS ONE 3(10): e3426
Mycobacterium tuberculosis is the principal etiologic agent of human tuberculosis. It has no environmental reservoir and is believed to have co-evolved with its host over millennia. This is supported by skeletal evidence of the disease in early humans, and inferred from M. tuberculosis genomic analysis. Direct examination of ancient human remains for M. tuberculosis biomarkers should aid our understanding of the nature of prehistoric tuberculosis and the host/pathogen relationship. We used conventional PCR to examine bone samples with typical tuberculosis lesions from a woman and infant, who were buried together in the now submerged site of Atlit-Yam in the Eastern Mediterranean, dating from 9250-8160 years ago. Rigorous precautions were taken to prevent contamination, and independent centers were used to confirmauthenticity of findings. DNA from five M tuberculosis genetic loci was detected and had characteristics consistent with extant genetic lineages. High performance liquid chromatography was used as an independent method of verification and it directly detected mycolic acid lipid biomarkers, specific for the M. tuberculosis complex. Human tuberculosis was confirmed by morphological and molecular methods in a population living in one of the first villages with evidence of agriculture and animal domestication. The widespread use of animals was not a source of infection but may have supported a denser human population that facilitated transmission of the tubercle bacillus. The similarity of the M. tuberculosis genetic signature with those of today gives support to the theory of a long-term co-existence of host and pathogen.
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Tags: Agriculture, Bacteria, Biology, Health, History, Medicine, Microbiology, Science, Tuberculosis
I find it to be one of the greatest tragedies that this disease is still so prevalent. Greed really is a killer.