Tuberculosis is not only still around, it’s the world’s leading infectious disease killer. In 2023, an estimated 10.8 million people developed new TB infections and 1.25 million died from the disease, surpassing even COVID-19 as a cause of death from a single pathogen. While many people in wealthier countries think of TB as a disease from another era, it remains a massive and growing global health crisis.
Where TB Is Most Common Today
TB hits hardest in low- and middle-income countries, particularly in parts of South and Southeast Asia, sub-Saharan Africa, and the Western Pacific. These regions account for the vast majority of cases worldwide. The reasons are straightforward: crowded living conditions, limited access to diagnostic labs, and health systems that struggle to deliver the months-long treatment TB requires.
High-income countries still see cases too, though the numbers are far smaller. In the United States, reported TB cases have been trending upward in recent years after decades of decline. Most U.S. cases occur in people who were born in or have traveled to countries where TB is common, but domestic transmission still happens, particularly in congregate settings like shelters and correctional facilities.
How TB Spreads
TB is an airborne disease. When someone with active TB in their lungs coughs, speaks, or even breathes, they release tiny particles containing the bacteria into the air. Those particles can remain suspended for several hours, especially indoors or in spaces with poor ventilation like closed vehicles. You cannot catch TB from touching surfaces, shaking hands, or sharing food.
This means prolonged indoor contact with an infected person is the primary risk scenario. Brief outdoor encounters are far less likely to result in transmission. The bacteria need time and a confined environment to reach your lungs in sufficient quantity to establish an infection.
Latent TB vs. Active TB Disease
Not everyone who breathes in TB bacteria gets sick. In fact, most don’t. The immune system can wall off the bacteria, trapping them in a dormant state. This is called latent TB infection. People with latent TB feel perfectly fine, have no symptoms, and cannot spread the disease to anyone else. They carry a small number of live but inactive bacteria in their body.
Active TB disease is a different situation entirely. The bacteria are multiplying, causing damage, and producing symptoms: a persistent cough lasting three weeks or more, chest pain, coughing up blood, fatigue, fever, night sweats, and unexplained weight loss. People with active pulmonary TB can spread the disease to others. Without treatment, active TB is frequently fatal.
Roughly 5 to 10 percent of people with latent TB will eventually develop active disease at some point in their lives. The risk is significantly higher for people with weakened immune systems, including those living with HIV, people undergoing chemotherapy, or those on immune-suppressing medications.
How TB Is Detected
Two main types of tests screen for TB infection. The tuberculin skin test involves injecting a small amount of protein under the skin of your forearm. You return to a clinic 48 to 72 hours later, and a healthcare worker measures any raised bump that has formed. The blood test approach (called an interferon-gamma release assay) requires a single blood draw with results typically available within 24 to 48 hours.
Both tests have similar overall accuracy, with sensitivities around 77 to 92 percent depending on the specific test. The blood test has one notable advantage: it’s more reliable in people who received the BCG vaccine, which is given routinely in many countries outside the United States. The skin test can produce false positives in BCG-vaccinated individuals, especially if the vaccine was given after infancy. Neither test can distinguish between latent infection and active disease on its own, so a positive result is typically followed by chest X-rays and, if needed, sputum samples.
Treatment Takes Months, Not Days
Standard TB treatment involves an intensive phase of about two months on multiple antibiotics, followed by a continuation phase lasting an additional two to seven months depending on the regimen and circumstances. The total course typically runs six to nine months. This is one of TB’s biggest practical challenges: patients start feeling better well before treatment is complete, and stopping early is one of the main drivers of drug resistance.
For drug-resistant forms of TB, treatment stretches dramatically. Multidrug-resistant TB, which doesn’t respond to the two most powerful first-line antibiotics, can require 18 to 24 months or longer of treatment with drugs that tend to have more side effects. In 2023, roughly 400,000 people worldwide developed multidrug-resistant TB. Low-income countries bear the heaviest burden of resistant cases, often lacking the lab capacity to detect resistance quickly enough to adjust treatment before the disease spreads further.
The causes of drug resistance are well understood. Incomplete treatment courses, improper prescribing, and inconsistent drug supply all give the bacteria opportunities to adapt. Once resistant strains emerge, they spread the same way regular TB does, through the air, creating a compounding problem that is especially difficult to control in under-resourced health systems.
Why the BCG Vaccine Isn’t Used Everywhere
A TB vaccine does exist. The BCG vaccine, developed over a century ago, is one of the most widely administered vaccines in the world. It is effective at protecting children from the most severe and deadly forms of TB, including TB meningitis. However, its protection against the most common form, pulmonary TB in adults, is highly variable. Some studies show strong protection, others show almost none, and the reasons for this inconsistency aren’t fully settled.
Because of this uneven performance in adults, countries with low TB rates, including the United States, don’t routinely give the vaccine. Instead, the U.S. strategy focuses on identifying and treating latent infections before they become active, combined with rapid detection and isolation of active cases. Countries with high TB burdens continue to vaccinate infants because the protection against severe childhood TB is reliable and saves lives, even if it doesn’t prevent all infections later in adulthood.
Why TB Persists in 2025
TB thrives on poverty, overcrowding, and weak healthcare infrastructure. It exploits conditions where people live in close quarters with poor ventilation, where diagnostic tools aren’t readily available, and where patients can’t always access or complete the long treatment courses required. HIV co-infection dramatically increases vulnerability, and the overlap between TB and HIV epidemics in sub-Saharan Africa has been particularly devastating.
Global progress against TB has been real but painfully slow. Incidence has declined over the past decade, yet the pace falls far short of what’s needed. The COVID-19 pandemic set things back further by disrupting TB diagnosis and treatment programs worldwide, contributing to the rebound in deaths that pushed TB back to the top of the infectious disease mortality rankings. The 7.5 million cases reported in 2022 jumped to 8.2 million in 2023, reflecting both genuine increases and improved case detection after pandemic disruptions.
For anyone wondering whether TB is a relic of the past, the numbers tell a clear story. A disease that kills over a million people a year and infects nearly 11 million more is not gone. It is one of the most persistent and deadly infections humanity faces, quietly ongoing even when it no longer makes headlines in wealthier nations.