Tuberculosis killed 1.3 million people in 2023, more than any other single infectious agent including HIV and malaria. It has held that grim record for most of human history. About 10.6 million people fell ill with TB that year, and roughly a quarter of the world's population carries latent TB infection. None of these numbers are new. What's new is that the bacteria are learning to resist the drugs that have kept TB manageable for the past 70 years.
WHO reported approximately 450,000 new cases of multidrug-resistant TB (MDR-TB) in 2023. Only about 2 in 5 of those patients were diagnosed and started on treatment. The rest went untreated, spreading resistant strains through their communities. Drug-resistant TB isn't just harder to treat. It's harder to find, harder to fund, and harder to stop.
What makes TB drug-resistant?
Standard TB treatment uses four first-line drugs: isoniazid, rifampicin, pyrazinamide, and ethambutol. A 6-month course cures over 95% of drug-susceptible cases. MDR-TB is defined as resistance to at least isoniazid and rifampicin, the two most powerful drugs in the regimen. Once those are gone, treatment becomes dramatically more difficult.
Resistance develops when patients take incomplete or inconsistent courses of antibiotics. Miss doses, run out of medicine, or stop treatment early because you feel better, and you've just given the surviving bacteria a selective advantage. Substandard or counterfeit drugs, a major problem in parts of India and sub-Saharan Africa, produce the same effect by delivering sub-therapeutic doses.
Health systems share the blame. Stockouts of TB drugs are common in high-burden countries. A 2019 survey by the Stop TB Partnership found that 69 countries reported stockouts of at least one first-line TB drug in the previous year. When a patient shows up at a clinic and the medicine isn't there, interrupted treatment is the predictable result.
XDR-TB (extensively drug-resistant TB) goes further. It resists isoniazid and rifampicin plus a fluoroquinolone and at least one additional Group A drug (bedaquiline or linezolid). Pre-XDR-TB resists isoniazid, rifampicin, and a fluoroquinolone. WHO updated these definitions in 2021 to reflect the new treatment regimens. Each escalation in resistance narrows the treatment options and worsens outcomes.
How long does treatment take?
Regular drug-susceptible TB: 6 months. Four drugs for 2 months, then two drugs for 4 months. Side effects are manageable. Cure rates exceed 95% with adherence.
MDR-TB treatment historically required 18-20 months of injectable and oral drugs with severe side effects: hearing loss from aminoglycosides, psychiatric effects from cycloserine, liver damage from ethionamide, peripheral neuropathy from linezolid. Patients described the treatment as worse than the disease. Cure rates hovered around 60%.
Newer regimens have shortened MDR-TB treatment significantly. The BPaL regimen (bedaquiline, pretomanid, linezolid), approved in 2019, can treat certain forms of drug-resistant TB in 6-9 months with all-oral drugs. The TB-PRACTECAL trial published in 2022 showed that a modified BPaL regimen achieved 89% favorable outcomes compared to 52% for the standard of care. A transformation in treatment, if patients can access the drugs.
WHO now recommends a 9-month all-oral regimen for MDR-TB patients without fluoroquinolone resistance. For patients with more extensive resistance, the BPaL-based regimen offers the best outcomes. But implementation lags far behind the guidelines. In 2023, only about 177,000 MDR-TB patients globally were enrolled in treatment out of the estimated 450,000 who fell ill.
What does drug-resistant TB cost?
Treating drug-susceptible TB costs approximately $100 per patient using generic first-line drugs. MDR-TB treatment costs $2,000-$10,000 depending on the regimen and country. XDR-TB can exceed $50,000-$100,000. That's a cost multiplier of 100-1,000x for a disease that could have been cured cheaply if it had been treated correctly the first time.
Bedaquiline, one of the most important new TB drugs, costs about $272 for a 6-month course through the Global Drug Facility's negotiated pricing. That price is available to qualifying low- and middle-income countries. The US list price is over $30,000 for the same course. Patent disputes and manufacturing concentration keep prices volatile. Johnson & Johnson's patent on bedaquiline expired in key markets in 2023, opening the door for generics, but production hasn't scaled to meet demand yet.
Beyond drug costs, MDR-TB treatment requires more lab capacity (drug susceptibility testing), more clinical visits, more side-effect monitoring, and more hospitalization. South Africa, which has one of the world's most advanced TB programs, spends roughly $17,000 per MDR-TB patient. For countries with annual per-capita health budgets under $50, that number is catastrophic.
Where is the burden highest?
Eight countries account for two-thirds of the world's TB cases: India, Indonesia, China, the Philippines, Pakistan, Nigeria, Bangladesh, and the Democratic Republic of Congo. India alone bears 27% of the global burden, with an estimated 2.8 million cases in 2023.
For drug-resistant TB specifically, India, China, the Russian Federation, and countries of the former Soviet Union carry disproportionate burdens. Russia's prison system has been a notorious incubator of MDR-TB for decades. Overcrowding, poor ventilation, delayed diagnosis, and frequent treatment interruptions when prisoners transfer between facilities create ideal conditions for resistance to develop and spread.
South Africa's MDR-TB crisis gained international attention after a 2006 outbreak of XDR-TB in Tugela Ferry, KwaZulu-Natal, where 52 of 53 patients died within an average of 16 days of diagnosis. Many were co-infected with HIV, which accelerates TB progression dramatically. Among people living with HIV, TB is the leading cause of death.
Central Asian countries (Kazakhstan, Uzbekistan, Tajikistan) report some of the highest proportions of MDR-TB among new TB cases, exceeding 20% in some settings. In contrast, Western Europe and North America see MDR-TB primarily among immigrant populations from high-burden countries.
Are travelers at risk?
Your risk of contracting TB during short-term travel is low but not zero. TB spreads through the air when someone with active pulmonary TB coughs, sneezes, or speaks. Casual outdoor contact is minimal risk. Prolonged indoor exposure is where transmission happens.
Backpackers sleeping in crowded dormitories, volunteers working in healthcare facilities, and long-term travelers living in local housing face meaningfully higher exposure than tourists staying in hotels. A 2018 study estimated that long-term travelers (>3 months) to high-burden countries had a TB infection rate of 2-3% per year of exposure, similar to the local population.
Pre-travel TB testing (tuberculin skin test or interferon-gamma release assay) establishes a baseline. Repeat testing 8-12 weeks after return can detect new infection. If you convert from negative to positive, you have latent TB that can be treated with a short course of preventive therapy before it progresses to active disease.
Why doesn't PandemicAlarm track TB as an outbreak?
PandemicAlarm monitors acute outbreak events: sudden surges, novel pathogens, geographic spread of epidemic-prone diseases. TB doesn't fit that model. It's endemic, not episodic. The 1.3 million deaths per year happen steadily, month after month, across dozens of countries. There is no outbreak curve to track because the curve never goes down.
However, drug-resistant TB outbreaks in specific settings (prisons, hospitals, communities) do occasionally generate the kind of acute cluster events that warrant alert-level attention. A 2016 outbreak of MDR-TB in a homeless community in Los Angeles infected 78 people over 18 months. Institutional outbreaks in Eastern European prisons have infected hundreds. PandemicAlarm may flag these clustered events when they appear in WHO or ProMED reporting, even though the broader TB epidemic falls outside our outbreak-focused model.
Understanding the drug-resistant TB crisis matters for anyone tracking pandemic threats. A pathogen that already infects 10 million people per year and is steadily evolving to resist available treatment fits every definition of a slow-moving emergency. New drugs like bedaquiline and pretomanid offer genuine hope, but only if they reach the patients who need them before resistance catches up again.