Tuberculosis (TB)

Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis, and it most often affects the lungs. TB can also reach the brain, kidneys, spine and lymph nodes. TB disease means the germs are growing and making a person sick¹. TB infection means the germs are in the body but are not causing illness¹. In its 2026 fact sheet, WHO calls TB the leading cause of death from a single infectious agent⁶. WHO estimated in 2026 that about a quarter of the global population has been infected with TB bacteria⁶. TB of the lungs is called pulmonary TB, and TB elsewhere is extrapulmonary TB, CDC noted in 2025⁹. It can affect more than one organ at the same time⁹.

A TB test is the only way to know whether the germs are in your body. The TB test guide covers the skin test and the blood test.

Tuberculosis is caused by a bacterium, Mycobacterium tuberculosis. A related germ, Mycobacterium bovis, causes a small number of cases. In inactive TB, the Mycobacterium tuberculosis bacterium lives in the body without making the person sick³. Disease starts when the body cannot stop the germs from growing⁹. A weak immune system, diabetes, cancer or HIV raises that risk². Some people get sick within weeks of infection, and others years later, when the immune system weakens². Being infected recently also raises the risk². In its 2026 fact sheet, WHO adds undernutrition, tobacco use and harmful alcohol use to the risks⁶.

You get tuberculosis by breathing in germs that a person with active TB of the lungs coughs, speaks or sings out. The germs can stay in indoor air for several hours². These five everyday contacts do not spread TB.

• Shaking hands
• Sharing food or drinks
• Touching bed linens or toilet seats
• Sharing toothbrushes
• Kissing

A person with active TB of the lungs or throat is contagious, while people with inactive TB cannot spread it to anyone³. Most spread happens between people who spend time together every day, which is how TB spreads in homes and workplaces². TB in other parts of the body, such as the kidney or spine, is usually not infectious². Symptoms may be mild for many months, so TB is easy to spread without knowing it, WHO noted in 2026⁶.

Tuberculosis symptoms appear only with active TB disease; inactive TB causes none. The main warning sign is a bad cough that lasts three weeks or longer⁷. Three signs point to the lungs.

• A cough that lasts 3 weeks or longer
• Chest pain
• Coughing up blood or sputum

Six signs affect the whole body⁷.

• Weakness or fatigue
• Weight loss
• No appetite
• Chills
• Fever
• Night sweats

TB growing elsewhere in the body gives other signs, depending on the part affected⁷. The full list of tuberculosis symptoms includes these five.

• Swollen lymph nodes
• Blood in the urine, from the kidney
• Headache or confusion, from the brain
• Back pain, from the spine
• Hoarseness, from the larynx

Inactive tuberculosis, also called latent TB infection, means the germs live in the body without making you sick. Active TB disease means the germs are growing, you feel ill and you can spread it.

Without treatment, 1 in 10 people with inactive TB get sick with active TB³. About 80% of US TB cases come from untreated inactive TB, CDC reported in 2025³. In its 2025 pages, CDC says inactive TB for what many sources call latent tuberculosis infection³.

Tuberculosis is diagnosed in two steps: a skin or blood test finds infection, then an X-ray and sputum tests find disease. A positive test alone cannot tell inactive TB from active TB.

1. A skin test, read 48 to 72 hours later on a second visit, or a blood test in one visit.
2. A chest X-ray.
3. Sputum smear and culture.
4. A treatment plan.

That is the usual order of how tuberculosis is diagnosed in the US⁸. A negative test makes TB unlikely, but more tests follow if there are symptoms, HIV or a recent exposure⁸. The skin test can take 2 to 8 weeks after infection to show a reaction⁸. The US has two FDA-approved blood tests, QuantiFERON-TB Gold Plus and T-SPOT.TB⁸. The blood test is preferred after the BCG vaccine and for people unlikely to come back for a skin test reading⁸. A positive result can stay positive after treatment, so keep a written record of it⁸.

Tuberculosis is treated with antibiotics taken for months, with several drugs together for active TB disease. Active TB takes 4, 6 or 9 months of treatment, and inactive TB takes 3 to 9 months. The standard 6-month tuberculosis treatment combines rifampin, isoniazid, pyrazinamide and ethambutol⁴. A 4-month regimen of rifapentine and moxifloxacin is an option for people 12 and older⁴. Health departments watch doses through directly observed therapy, in person or by video⁴. Most people feel well after a few weeks, but the germs are still alive and the medicine must be finished⁴. A missed dose is skipped, the next dose is taken on schedule, and the provider is told⁴. Rifampin and rifapentine can turn urine, tears, sweat and saliva orange, which is harmless⁴.

Yes, tuberculosis can be cured with a full course of antibiotics. Treatment with first-line drugs succeeded for 88% of people with drug-susceptible TB worldwide in 2023, WHO reported in 2025. WHO states in its 2026 fact sheet that TB is curable and preventable⁶. Drug-resistant TB can take months or years to treat and is managed with a TB expert⁴. Stopping the medicine too soon can make a person sick again, and the germs still alive can become resistant⁴. In its 2026 fact sheet, WHO defines multidrug-resistant TB as TB that does not respond to rifampin and isoniazid⁶. Those are the two most effective first-line drugs⁶. Most healthy people will not need TB treatment again⁴.

Tuberculosis usually attacks the lungs, where active disease causes a lasting cough, chest pain and coughing up blood or sputum. Without treatment, active TB can be fatal⁹. Inhaled germs reach the air sacs, called alveoli, where immune cells called macrophages take them up, CDC explained in 2025⁹. In a minority of cases, part of a granuloma breaks down into a cavity (Marchal, 1997). There the germs multiply fast and can seed other parts of the lung. The germs can spread from the lungs to the brain, kidneys or spine¹. Symptoms then depend on the part affected, as the guide to what tuberculosis does to the body explains⁷.

Tuberculosis is uncommon in the United States, with 10,260 cases counted in 2025, a rate of 3.0 per 100,000. The 2025 count is provisional, CDC noted in 2026. People born abroad had a 2025 rate of 15.4 per 100,000, against 0.8 for US-born people⁵. Both figures come from the count of tuberculosis cases in the US. CDC estimated in 2025 that as many as 13 million people live with inactive TB¹. The final 2024 US count was 10,388 cases, a rate of 3.1 per 100,000⁵. In 2023, 572 people died of TB in the US⁵. Worldwide, 10.7 million people fell ill and 1.23 million died in 2024, WHO reported in 2026⁶.

Tuberculosis is prevented mainly by finding and treating inactive TB before it turns into disease. Treatment of inactive TB takes 3 or 4 months with the preferred short regimens⁴. Testing people who spent time with someone with active TB is a key way to prevent tuberculosis². Spread is more likely indoors and where air circulation is poor². The BCG vaccine is not used widely in the US, CDC noted in 2025¹. Treating inactive TB is 90% effective at preventing TB disease, CDC reported in 2025³. In countries where TB is common, babies and small children get the BCG vaccine⁶. WHO said in 2026 that it protects children from serious forms of TB⁶.

These short answers cover the questions people often ask next.