Abstract
Mycobacterium tuberculosis has affected human populations for the past several thousand years. But despite the antiquity of the disease, we know little about where the bacteria originated and how it spread across the globe. How and when tuberculosis arrived in the Pacific is particularly unclear. Extant tuberculosis strains in the Pacific indicate that tuberculosis was introduced by Europeans in the 18th-19th centuries. However, pre-European skeletal evidence consistent with tuberculosis suggests a different story. A new hypothesis suggests that tuberculosis was first introduced by pinnipeds and subsequently jumped host. Both modern and ancient cases of seal-to-human transmission are known, and archaeological evidence shows us that people were processing seals in the Pacific, where they were present.
With advanced DNA technologies, this study aimed to confirm the presence of M. tuberculosis in pre-European Pacific populations. A total of 19 bioarchaeological samples (from 14 individuals) were tested, that originate from the archaeological sites of Wairau Bar, New Zealand (750 BP), and Uripiv, Vanuatu (2800 BP). Sites were selected based on the presence of tuberculosis-like skeletal lesions in some of the human skeletal remains. We included 10 samples taken directly from the area of the tuberculosis-like bone lesions, 4 bone samples without any visible lesions, and 5 tooth samples. For all samples, metagenomic shotgun sequencing data and/or hybridization capture sequencing data was generated, which was subsequently processed with state-of-the-art bioinformatic tools.
Following three authenticity criteria (evenness of coverage, percent identity and haploidy), there is no convincing DNA evidence for the presence of M. tuberculosis or any other pathogens that could have caused the tuberculosis-like skeletal lesions at these sites, which is likely due to the insufficient DNA preservation. While it could not be resolved what pathogen had caused these lesions in the individuals from Wairau Bar and Uripiv, the created pathogen screening pipeline is considered a great outcome, and has positively identified other (pathogenic) bacteria, including Bacillus cereus, and several oral microbiome species (e.g. Treponema denticola and Porphyromonas gingivalis).