Ancient skeletal evidence for leprosy in India (2000 B.C.)

Abstract

Background: Leprosy is a chronic infectious disease caused by Mycobacterium leprae that affects almost 250,000 people worldwide. The timing of first infection, geographic origin, and pattern of transmission of the disease are still under investigation. Comparative genomics research has suggested M. leprae evolved either in East Africa or South Asia during the Late Pleistocene before spreading to Europe and the rest of the World. The earliest widely accepted evidence for leprosy is in Asian texts dated to 600 B.C.

Methodology/principal findings: We report an analysis of pathological conditions in skeletal remains from the second millennium B.C. in India. A middle aged adult male skeleton demonstrates pathological changes in the rhinomaxillary region, degenerative joint disease, infectious involvement of the tibia (periostitis), and injury to the peripheral skeleton. The presence and patterning of lesions was subject to a process of differential diagnosis for leprosy including treponemal disease, leishmaniasis, tuberculosis, osteomyelitis, and non-specific infection.

Conclusions/significance: Results indicate that lepromatous leprosy was present in India by 2000 B.C. This evidence represents the oldest documented skeletal evidence for the disease. Our results indicate that Vedic burial traditions in cases of leprosy were present in northwest India prior to the first millennium B.C. Our results also support translations of early Vedic scriptures as the first textual reference to leprosy. The presence of leprosy in skeletal material dated to the post-urban phase of the Indus Age suggests that if M. leprae evolved in Africa, the disease migrated to India before the Late Holocene, possibly during the third millennium B.C. at a time when there was substantial interaction among the Indus Civilization, Mesopotamia, and Egypt. This evidence should be impetus to look for additional skeletal and molecular evidence of leprosy in India and Africa to confirm the African origin of the disease.

Figure 1. The excavation site in Balathal.

A) A map of India showing the location of Balathal and a view of the lower town. B) Photograph of the excavations within the stone enclosure where skeleton 1997-1 was located. This individual was interred in the Chalcolithic deposit (layer 7) of stratified layers of burned cow dung. Associated radiocarbon dates indicate an antiquity of cal B.C. 2000.

Figure 2. Plan view of the Chalcolithic occupation at the site of Balathal.

Balathal Phases I–III Chalcolithic structures uncovered during the 1994–1997 excavation seasons. The skeleton was uncovered in layer 7 of quadrant E3 and the radiocarbon date of 2000 B.C. was obtained in layer 7 of quadrant F4, both of which are within the stone enclosure. The Early Historic phase is not represented here as that portion of the site was excavated in 1999–2002.

Figure 3. The cranium of individual 1997-1.

A) Anterior view demonstrates bilateral erosive lesions at the supraorbital region and glabella, erosion/remodeling of the margin of the nasal aperture, including the anterior nasal spine, bilateral necrosis of the infraorbital region of the maxilla, and resorption of the alveolar region of the maxilla with associated antemortem tooth loss. B) Inferior view of the maxilla demonstrates pathological changes to the palatine process including pitting near the midline and in the alveolar region.

Figure 4. Anterior view of the mandible from individual 1997-1.

The mandible demonstrates root exposure, alveolar resorption, antemortem tooth loss, and a small apical abscess at the left third premolar.

Figure 5. Elements demonstrating pathological conditions in the postcranial skeleton of individual 1997-1.

A) Left lateral view of the cervical vertebrae (C3–C7) demonstrates degenerative changes including ventral wedging, osteophytosis, and ankylosis. B) Three views (from the radius, from the triquetral, and the palmar-distal surface) of the left pisiform demonstrating a fracture on the articular surface for the triquetral. C) Lateral view of the tibia midshaft. Arrow points to periostitis on the compact bone surface.