Health
Once thought to have originated in cows and spread through dust, the surprising evolutionary story of tuberculosis reveals why it’s so hard to stamp out this ancient disease, writes Carl Zimmer
By Carl Zimmer
We are starting to understand why the bacteria behind tuberculosis is so good at infecting people
Adobe Stock/Ryan Wills
When we look back over the history of infectious diseases, it’s the explosive pandemics that grab our attention. Cholera and plague terrify us with their swift destruction of cities and the paralysis they cause across whole nations, while the devastation brought about by quieter diseases can be easy to overlook.
And perhaps no disease has wreaked more havoc under the radar than tuberculosis. Creeping from person to person, slowly killing its victims over the course of years, Mycobacterium tuberculosis has caused more cumulative suffering than any flashier pathogen.
And it continues to wreak havoc. While smallpox was eradicated in the 1970s and very few people now die from plague, tuberculosis is continuing its deadly rampage. Roughly a quarter of all people alive today have been infected with M. tuberculosis. In 2023 alone, tuberculosis killed 1.2 million people – about twice the number of deaths caused by HIV or malaria.
“The fact that TB still kills and sickens so many people is an outrage, when we have the tools to prevent it, detect it and treat it,” the World Health Organization’s Tedros Ghebreyesus said in 2024.
Besides lack of political will, there is another reason for TB’s success, one that has to do with the microbe itself. M. tuberculosis has evolved into an astonishingly adept human pathogen. And one of its greatest skills is its ability to fly through the air.
The hunt for TB’s cause
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