Over 200 visitors interacted with each other over themes of drug resistant tuberculosis, extra-pulmonary TB and developments ways of diagnosis of TB.
Hyderabad: The bacterium that causes tuberculosis disease, Mycobacterium tuberculosis, has probably co-evolved with humans for at least 40,000 years. While the earliest known record of the bacterium being found in ancient DNA is from the Neanderthals, are an extinct group of humans who lived in Eurasia (the area comprising Europe and Asia),some recent studies shed light on the past and present of both bacteria and humans.
This was shared by Prof. Sarah Dunstan from University of Melbourne, who presented her study at a conference on 'heterogeneity in hosts and pathogens of tuberculosis' at CCMB on Monday.
Using human genetics and Mycobacterium tuberculosis, she explored the idea that East Asia's population history was shaped by two main waves: one from the south (hunter-gatherers) and another from the north (agriculturalists). The research opens the door for studies on how humans and pathogens might have evolved together in this region.
"The migration of humans into Asia is a complex story. We have studied the Y chromosome data and how it relates to indigenous and non-indigenous populations across the continent,” Prof. Dunstan said.
A model called the two-layer hypothesis suggests that Asia was populated in two major phases, with the first migration happening between 50,000 and 65,000 years ago, when small hunter-gatherer groups moved around the southern rim of the Indian Ocean. The second migration, around 45,000 years ago, saw groups move north of the Himalayas, eventually spreading into Siberia, East Asia, and China," she explained.
The development of agriculture about 9,000 years ago marked a shift, as people moved from hunter-gatherer lifestyles to settled communities, leading to the spread of populations throughout Asia, she said.
“We looked at tuberculosis (TB) lineages, specifically Lineage 1 and Lineage 2, and found that their spread mirrored human migration patterns. Lineage 2, which arose in Asia and is more transmissible, followed the pattern of those migrating north of the Himalayas,” Prof. Dunstan said.
“Lineage 1, which is less transmissible, seemed to correspond with the early hunter-gatherer groups that moved around the southern rim of the Indian Ocean, where the bacteria adapted to spread less to avoid wiping out small populations," she elaborated.
As agricultural societies formed, TB adapted to spread more easily because larger populations in cities provided more hosts, making it more virulent.
"This allowed it to spread without risking the extinction of the bacteria, unlike in small, isolated hunter-gatherer groups. Our research shows that people and TB have co-evolved over millennia, with the bacteria adapting to different human groups based on their demographic and societal structures," the researcher said.
Prof. Dunstan's study is significant as it helps mark the co-evolution of both the bacteria and humans and guide biologists for studying the disease and how it spreads in the region.
"Though we are using current bacterial isolates and modern human data to infer past events, ancient DNA, including mycobacterium found in Neanderthal remains, suggests that TB has been evolving with humans for at least 40,000 years. This study demonstrates the long history of human-TB co-evolution, where the bacteria's transmission patterns change based on the human groups it infects, influenced by their lifestyle and population dynamics," she said.
The conference that will continue till February 12 has other similar studies being presented from researchers across the globe. The workshop provided opportunities to students to present their ideas in one-minute flash talks and posters on display.
Over 200 visitors interacted with each other over themes of drug resistant tuberculosis, extra-pulmonary TB and developments ways of diagnosis of TB.
