Blame European explorers and colonizers for possibly spreading tuberculosis around the world hundreds of years ago, according to a new study.

Researchers the Norwegian Institute of Public Health traced back the evolution of the most common strain of tuberculosis and how it became resistant to antibiotics. They found that the emergence of the disease in the Americas, Asia, and Africa coincided with the arrival of conquistadores and missionaries. 

History Of Tuberculosis

In the study published by the journal Science Advances, the researchers decided to focus on Lineage 4 TB, the most common strain of TB around the world. There are two prominent theories that explain the evolution of the infectious disease: the first suggests that it started in Africa about 70,000 years ago while the second claims that it emerged in Africa much later at around 4,000 to 6,000 years ago. 

However, it might have been the Europeans who carried and spread the disease around the world. While it does not negate the theories that TB started in Africa, European explorers who traveled by sea to reach the most far-flung regions around the world to conquer new territories and preach their religion to the natives might have also carried the disease. 

For example, the study showed that Lineage 4 TB first appeared in the Republic of Congo during the 15th Century, around the time that Portuguese trading ports were established in the Gold Coast (Ghana) in 1482. 

"In Western Africa, Lineage 4 is the dominant form of TB but Lineages 5 and 6 are also common. These lineages cause a lesser disease burden and do not transmit as well," explained study co-author Francois Balloux. "It is likely that with the arrival of the European Lineage 4 replacing less aggressive lineages in this region, TB became a lot more common and virulent."

In South America, Lineage 4 TB appeared at around 1492, shortly after the Europeans arrived in the continent. The outbreak was recorded and peaked around the 17th century. 

The Tuberculosis Problem

Tuberculosis, or TB, is an infectious disease that affects millions of people around the world. In 2017, the World Health Organization reported that 10 million people are suffering from the disease, 1.6 million of which have died. 

While the disease is preventable and can be treated, multi-drug resistant TB is increasingly becoming a public health crisis. The researchers hope that their recent study could provide an insight into the spread of TB around the world and help prevent the disease from affecting more people.