Tuberculosis 70,000 years - RTVE

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tuberculosis bacteria -now classified as Mycobacterium tuberculosis and Mycobacterium africanum-approximately 70,000 years appeared in Africa and accompanied modern humans who left the continent to populate Europe and Asia, according to a study published in the journal Nature Genetics.

This is the main conclusion of this work, in addition to Iñaki Comas, the Centre of Public Health Research (CSISP-Fisabio, Valencia), researchers involved Switzerland, United Kingdom and China.

tuberculosis, even though today is a curable disease , cause is still around 1.4 million deaths a year worldwide, and it is estimated that infects one third of the population world.

“Double face” of the disease

This is one of the faces of this condition, the other that only between 5 and 10% of infected persons develop tuberculosis , since the bacteria, though present in the lungs of patients can be kept dormant through the work of the immune system, capable of containing, as Comas.

Precisely this

“double face” of the disease is what has led the group to conduct this research Comas.

To do this, and try to understand the evolutionary origin of the bacteria, the scientists sequenced the genome of 259 strains representing areas of Africa, Europe, America and Asia.

From there, they took a number of conclusions, including the tuberculosis bacterium has 70,000 years (scientists estimate the age by genetic mutations suffered).

“evolutionary analyzes have allowed us to infer that the association between TB bacteria and humans may date from about 70,000 years,” he asserted Comas, who has suggested that this “came along with local residents out of Africa “ (it is estimated that this could have occurred 65,000 years ago).

bacteria, Comas continued, “and infect humans before they left Africa.”

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addition of dating and locating the bacteria, this study suggests that there is probably a less virulent form of this organism , limited by the low number of hosts available-the only reservoir of the bacteria are humans -.

In this sense, Comas and colleagues propose that the bacterium has evolved into a more virulent state .

“We believe that when there is population explosion, as occurred in the Neolithic or the industrial revolution, are selected more virulent forms of bacteria; spreads and infects faster”, has riveted Comas.

For this scientist, this has been able to accommodate population changes , and can prevent its own extinction even in very small populations, “humanity’s success has also led to the success of the bacteria and, therefore, of the disease. “

This work also shows that among all analyzed genomes of different strains have identified seven genetic lineages or groups, with more than 30,000 genetic differences.

It is, as Comas, a “valuable resource” for tuberculosis research community, which will help establish diagnoses and design new potential drugs. Specifically, the group Comas is now trying to find which of these genetic changes 30,000 are related to virulence.

Comas

also stressed that this study was made possible by the use of massive sequencing technologies, a change in the analysis that was not possible just ten years ago.

This is not the only study on tuberculosis published by Nature Genetics. In the last issue are three others that address antibiotic resistance to this disease.

one, Maha Farhat, Massachusetts General Hospital, identified after sequencing of 123 strains of tuberculosis, 39 new drug-resistant regions.