Why can’t we defeat the oldest disease known to humankind?

TUBERCULOSIS (‘TB’) HAS BEEN AROUND FOR A LONG TIME. Anyone with basic knowledge about the disease will tell you that we have  found traces of the bacteria and the deformities it causes in human remains dating back thousands of years. This has led to the infamous claim that TB is the oldest disease known to humankind. By the time Robert Koch “discovered” the Mycobacterium tuberculosis in 1882, TB had gone by many names — phthisis, consumption, the white plague, scrofula, the King’s Evil. It had also claimed countless lives as a leading cause of human death throughout history, killing over 1 billion people just since Koch identified the bacteria. The stigma surrounding TB started early as well. Hippocrates warned his students against treating people with TB because nearly all of them would die, and this would harm the students’ reputations.

How is it, then, that this ancient disease still kills millions of people, more than HIV and malaria combined each year, making it the world’s deadliest infectious agent? The answer is complicated, involving how the disease spreads, the bacteria’s unique physiology, and the socio-economic disparities that drive the epidemic. 

But in some ways, it’s a simple narrative of poverty and neglect. This story is reflected in graphs showing the precipitous decline of TB mortality in the United States as living conditions and occupational health and safety standards improved well before we discovered streptomycin* or widely administered the Bacillus Calmette–Guérin (‘BCG’) vaccine (see figure 1 below). Today, we have better tools to detect, prevent, and treat TB and a deeper understanding of its socio-economic determinants. Yet we are still struggling — some would say failing — to eradicate the disease because of years of global neglect and failed approaches. 

According to the World Health Organisation (WHO), approximately 10.8 million people fell ill, and 1.25 million people died from TB in 2023, the most recent year for which complete data is available. At almost 11 million, the total number of new cases reflects a slight increase from the year before and a broader trend of rising global TB incidence since the COVID-19 pandemic started in 2020. Thirty so-called “high TB burden” countries accounted for 87 percent of the total TB cases in 2023, with five countries constituting 56 percent of the worldwide total — India (26 percent), Indonesia (10 percent), China and the Philippines (6.8 percent each) and Pakistan (6.3 percent). Alarmingly, 25 percent of the people who fell ill with TB in 2023 were not registered by their national TB programs, meaning many, if not most, of them went undiagnosed or untreated. This global gap, sometimes called the “missing millions,” reflects the persistent challenges in finding, diagnosing, and treating people with the disease.