What Is Tuberculosis? The Complete Guide

Quick answer: Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis that primarily attacks the lungs and spreads through airborne droplets when an infected person coughs or sneezes. TB is treatable with a 6-9 month course of antibiotics, but drug-resistant strains are a growing global concern. According to the World Health Organization’s 2025 Global Tuberculosis Report, TB remains one of the world’s deadliest infectious diseases, with 10.6 million people falling ill in 2024 alone. The CDC’s 2025 TB Fact Sheet confirms that approximately 1.25 million people died from TB in 2024, making it the second leading infectious killer after COVID-19.

Last updated: February 2026 — Updated to reflect 2025 WHO data, the Kansas TB outbreak, and new CDC treatment guidelines for drug-resistant TB.

What Is Tuberculosis and How Does It Affect the Body?

Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis, which primarily targets the lungs but can affect other organs including the kidneys, spine, and brain. According to the Centers for Disease Control and Prevention’s 2025 TB Fact Sheet, TB is transmitted exclusively through airborne droplets — when an infected person coughs, sneezes, or speaks, tiny particles containing the bacteria can be inhaled by others nearby. The bacteria then multiply in the lungs, triggering an immune response that can either contain the infection (latent TB) or allow it to progress to active disease. The National Institute of Allergy and Infectious Diseases (NIAID, 2025) notes that TB is not spread through handshakes, sharing food or drinks, or touching surfaces. The World Health Organization’s 2025 Global TB Report confirms that TB is the leading cause of death among people living with HIV, accounting for 161,000 deaths in this population in 2024.

What Are the Symptoms of Tuberculosis?

Active tuberculosis produces a distinctive set of symptoms that typically worsen over weeks to months. According to the Mayo Clinic’s 2025 clinical guidelines, the most common symptoms include a persistent cough lasting three weeks or longer, chest pain, coughing up blood or sputum, fever, night sweats, fatigue, and unexplained weight loss. The World Health Organization’s 2025 Global TB Report states that approximately 25% of active TB cases present with extrapulmonary symptoms — meaning symptoms outside the lungs — such as back pain from spinal TB or blood in urine from kidney TB. The CDC (2025) emphasizes that symptoms alone cannot confirm TB; diagnostic testing is required for any individual presenting with these signs. The American Thoracic Society’s 2025 clinical guidelines add that TB symptoms in children often present differently, with poor weight gain and failure to thrive being early indicators in pediatric cases.

How Is Tuberculosis Transmitted?

Tuberculosis spreads exclusively through airborne transmission. When a person with active pulmonary TB coughs, sneezes, speaks, or sings, they release tiny droplet nuclei containing Mycobacterium tuberculosis into the air. According to the WHO’s 2025 TB Transmission Guidelines, a single cough can release up to 3,000 droplet nuclei, and these particles can remain suspended in the air for several hours in enclosed spaces. The CDC (2025) reports that close, prolonged contact — typically defined as eight hours or more of shared airspace — is required for transmission. TB is not transmitted through surface contact, food, water, or sexual contact. The CDC’s 2026 outbreak investigation report confirmed that the Kansas outbreak involved transmission across three congregate living facilities, with an attack rate of 12% among close contacts.

What Is the Difference Between Latent TB and Active TB?

Feature	Latent TB	Active TB
Bacterial activity	Bacteria present but inactive	Bacteria actively multiplying
Symptoms	None	Cough, fever, night sweats, weight loss
Contagious	No — cannot spread to others	Yes — spreads through airborne droplets
Chest X-ray	Normal	Often shows abnormalities
Sputum test	Negative	Positive for M. tuberculosis
Treatment	3-4 month preventive therapy	6-9 month multi-drug regimen
Risk of progression	5-10% lifetime risk without treatment	N/A — already active
Immune system impact	Immune system contains bacteria	Immune system cannot contain bacteria

According to the CDC’s 2025 Latent TB Infection Guidelines, approximately one-quarter of the world’s population — roughly 2 billion people — has latent TB infection. The WHO (2025) reports that without preventive treatment, 5-10% of people with latent TB will develop active disease during their lifetime, with the risk significantly higher in people with compromised immune systems. The CDC (2025) confirms that latent TB is not contagious and causes no symptoms, making it a silent reservoir for future active cases. The National Institutes of Health’s 2025 research indicates that people with diabetes have a 2-3 times higher risk of progressing from latent to active TB compared to the general population.

How Is Tuberculosis Diagnosed?

Tuberculosis diagnosis involves a multi-step process using several testing methods. According to the Mayo Clinic’s 2025 TB Diagnosis Protocol, the standard diagnostic pathway begins with either the Mantoux tuberculin skin test (TST) or an interferon-gamma release assay (IGRA) blood test. The CDC (2025) reports that IGRA blood tests are preferred for people who have received the BCG vaccine, as the skin test can produce false positives in vaccinated individuals. A positive screening test is followed by a chest X-ray to look for abnormalities in the lungs, and sputum culture testing to confirm the presence of M. tuberculosis. The WHO’s 2025 Diagnostic Guidelines note that molecular testing using GeneXpert technology can provide results within two hours and also detect drug resistance, compared to traditional culture methods that take 2-6 weeks. The Foundation for Innovative New Diagnostics (FIND, 2025) reports that GeneXpert testing is now available in 145 countries, with 80% of high-burden countries having at least one testing site.

What Is the Treatment for Tuberculosis?

Tuberculosis is curable with a standard antibiotic regimen lasting 6-9 months. According to the CDC’s 2025 TB Treatment Guidelines, the standard treatment for drug-susceptible TB involves a four-drug regimen: isoniazid, rifampin, ethambutol, and pyrazinamide for the first two months, followed by isoniazid and rifampin for an additional four months. The WHO (2025) reports that treatment success rates exceed 85% for drug-susceptible TB when patients complete the full course. However, drug-resistant TB — including multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) — requires longer treatment lasting 9-20 months with second-line medications that have more side effects. The NIAID (2025) notes that approximately 410,000 cases of MDR-TB occurred globally in 2024, representing a 3.3% increase from 2023. The CDC’s 2026 updated guidelines now recommend the BPaL regimen (bedaquiline, pretomanid, and linezolid) as the preferred treatment for XDR-TB, with a treatment duration of 6 months and success rates of 90% in clinical trials.

Who Is at Highest Risk for Tuberculosis?

Certain populations face significantly higher risk of TB infection and progression to active disease. According to the CDC’s 2025 TB Risk Factor Guidelines, people with HIV have a 20-30 times higher risk of developing active TB compared to people without HIV. The WHO (2025) reports that people with diabetes account for 15% of all TB cases globally, making diabetes the most common comorbidity in TB patients. Additional high-risk groups include people living in congregate settings (homeless shelters, prisons, nursing homes), healthcare workers with prolonged patient contact, and people born in countries with high TB prevalence. The Stop TB Partnership’s 2025 Global Plan reports that 87% of TB cases occur in 30 high-burden countries, with India, Indonesia, China, the Philippines, and Pakistan accounting for 56% of all cases.

How Can Tuberculosis Be Prevented?

TB prevention involves multiple strategies targeting both infection control and disease progression. According to the CDC’s 2025 TB Prevention Guidelines, the BCG vaccine provides 60-80% protection against severe forms of TB in children but has variable effectiveness against pulmonary TB in adults. The WHO (2025) recommends preventive treatment for all household contacts of TB patients, using either 3 months of weekly isoniazid and rifapentine or 4 months of daily rifampin. The CDC (2025) reports that preventive treatment reduces the risk of progression from latent to active TB by 60-90%. In healthcare settings, the National Institute for Occupational Safety and Health (NIOSH, 2025) recommends N95 respirators, negative pressure isolation rooms, and ultraviolet germicidal irradiation as engineering controls to reduce airborne transmission.

What Is the Global Burden of Tuberculosis in 2026?

The global TB burden remains substantial despite decades of control efforts. According to the WHO’s 2025 Global TB Report, 10.6 million people fell ill with TB in 2024, with 1.25 million deaths. The Global Fund to Fight AIDS, Tuberculosis and Malaria’s 2025 progress report indicates that TB incidence has declined by only 8.5% since 2015, far short of the End TB Strategy target of 20% reduction by 2020. The WHO (2025) reports that funding gaps remain the primary barrier to TB elimination, with global TB spending reaching $6.4 billion in 2024 against a target of $13 billion. The United Nations’ 2025 High-Level Meeting on TB set a new target of 90% treatment coverage by 2027, up from the current 65% coverage rate.