The existence of tuberculosis in the preColumbian Americas is controversial because the morphology of the lesion is not specific, the organism is culturally nonviable in ancient tissues, and nonpathogenic soil mycobacteria can contaminate buried bodies. We report the recovery of DNA unique to Mycobacterium tuberculosis from a lung lesion of a spontaneously mummified, 1000-year-old adult female body in southern Peru. This provides the most specific evidence possible for the pre-Columbian presence of human tuberculosis in the New World.
Tissue specimens from 283 principally spontaneously (naturally) desiccated human mummies from coastal and low valley sites in northern Chile and southern Peru were tested with a DNA probe directed at a kinetoplast DNA segment of Trypanosoma cruzi.
Analysis of 483 skeletons from Arica (Chile) and review of mummy dissection records demonstrates an overall 1% prevalence rate for tuberculosis between 2000 B.C. and A.D. 1500. Tuberculosis cases cluster in the period A.D. 500-1000 which correlates with fully agropastoral societies. Considering only these agropastoral societies, about 2% of their members show tuberculosis lesions. A segment of DNA unique to Mycobacterium tuberculosis was identified in an extract from the vertebral lesion of a 12-year-old girl with Pott's disease from about A.D. 1000, establishing the pre-Columbian presence of tuberculosis with the most specific evidence currently available.
Scanning electron microscopy in conjunction with cell isolation procedures revealed details of the packing of threads in hagfish slime gland thread cells. Biochemical studies indicate that the thread is largely composed of a protein subunit with a molecular weight of 63,500. Mathematical calculations suggest that the thread may attain lengths of 60 centimeters or more.
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