Tuberculosis (TB)

How TB spreads

When someone with active TB of the lungs or throat coughs, sneezes, speaks or sings, tiny droplets containing bacteria hang in the air. Others breathe them in. Spread usually requires prolonged, close contact in indoor spaces, such as households.

TB is not spread by shaking hands, sharing food or drinks, touching bedding or toilet seats, or kissing.

People with latent TB or with TB outside the lungs are generally not contagious. Most people with active lung TB stop being contagious after about 2 weeks of effective treatment.

Latent TB vs active TB

Without treatment, about 5 to 10% of people with latent TB develop active TB during their lifetime, with the highest risk in the first 2 years after infection. The risk is much higher with HIV.

Symptoms of active TB

Lung (pulmonary) TB

• cough lasting 3 weeks or more, often with sputum
• coughing up blood
• chest pain, especially when breathing or coughing
• fever and chills
• night sweats
• unexplained weight loss and loss of appetite
• fatigue

TB outside the lungs (extrapulmonary)

• lymph nodes: painless swelling, often in the neck
• spine (Pott disease): back pain and stiffness
• kidneys: blood in the urine
• brain (TB meningitis): headache, confusion, stiff neck
• pleura: fluid around the lungs, breathlessness
• abdomen, joints, heart lining and other organs

Risk factors

For infection

• close contact with someone with active TB
• living in or coming from countries with high TB rates
• living or working in prisons, shelters, nursing homes or healthcare settings

For developing active disease

• HIV infection, the strongest risk factor
• recent infection (within 2 years)
• diabetes
• medicines that suppress immunity, including TNF inhibitors and long-term steroids
• organ transplant, kidney failure on dialysis
• silicosis
• smoking, alcohol use disorder, malnutrition, low body weight
• young children under 5 and older adults

Testing and diagnosis

Tests for TB infection

• TB skin test (tuberculin skin test, TST): a small injection under the skin of the forearm, read 48 to 72 hours later. Prior BCG vaccine can cause false positives.
• TB blood test (interferon-gamma release assay, IGRA): a single blood draw, not affected by BCG vaccination; preferred for many adults.

Neither test can tell latent from active TB.

Tests for TB disease

• chest X-ray or CT scan
• sputum tests: smear microscopy, rapid molecular tests (such as Xpert MTB/RIF, which also detects rifampin resistance) and culture
• drug susceptibility testing
• biopsies or fluid samples for TB outside the lungs
• HIV test for everyone diagnosed with TB

Treatment

TB treatment must be taken for the full course, even after feeling better, to cure the infection and prevent drug resistance. Public health departments often provide directly observed therapy (DOT), including video DOT.

Latent TB

Preferred short-course regimens recommended by the CDC:

• 3HP: isoniazid and rifapentine once weekly for 3 months
• 4R: rifampin daily for 4 months
• 3HR: isoniazid and rifampin daily for 3 months

Longer isoniazid-only regimens (6 to 9 months) are alternatives.

Active, drug-susceptible TB

• the standard regimen is 4 drugs (isoniazid, rifampin, pyrazinamide and ethambutol) for 2 months, then isoniazid and rifampin for 4 more months
• a 4-month regimen of rifapentine and moxifloxacin with other drugs is an option for some people aged 12 and older
• longer treatment for TB of the brain, bones or joints

Drug-resistant TB

Multidrug-resistant TB (resistant to at least isoniazid and rifampin) is treated with newer all-oral regimens, such as bedaquiline, pretomanid, linezolid and moxifloxacin (BPaLM) for 6 months, under specialist care.

Side effects to watch for

• liver injury: nausea, vomiting, belly pain, yellow skin or eyes, dark urine
• rifampin turns urine, tears and sweat orange; it also reduces the effectiveness of hormonal birth control and many other medicines
• isoniazid can cause numbness or tingling; vitamin B6 is often given to prevent this
• ethambutol can affect vision; report any vision changes

Avoid alcohol during treatment and tell your doctor about all medicines.

Prevention

• finding and treating latent TB in people at risk
• testing close contacts of people with active TB
• treating active TB quickly and completely
• ventilation, masks and isolation during the infectious period
• BCG vaccine: given to infants in many countries; it protects young children against severe forms of TB but is rarely used in the US

Frequently asked questions

What are the first signs of tuberculosis?

Early signs of active lung TB include a cough lasting 3 weeks or more, fatigue, low-grade fever, night sweats, loss of appetite and weight loss. Coughing up blood or chest pain may follow. Latent TB causes no symptoms.

What is the difference between latent TB and active TB?

Latent TB means TB bacteria are in your body but inactive: you feel well, are not contagious, and your chest X-ray is normal. Active TB means the bacteria are multiplying and causing illness, and lung TB can spread to others.

How is TB spread?

TB spreads through the air when a person with active TB in the lungs or throat coughs, speaks or sings, and others breathe in the bacteria. It usually requires prolonged close contact. It does not spread through touching surfaces, sharing food or shaking hands.

Is tuberculosis curable?

Yes. Both latent and active TB are curable with antibiotics. Active drug-susceptible TB is usually cured with 4 to 6 months of treatment. Drug-resistant TB takes longer but is increasingly curable with newer regimens.

What does a positive TB skin test mean?

A positive TB skin test or blood test means you have been infected with TB bacteria at some point. It does not show whether the infection is latent or active. A chest X-ray and evaluation for symptoms are needed, and treatment for latent TB is usually recommended.