Tuberculosis, or “TB,” is a highly contagious infectious disease that mainly affects the lungs. According to the Centers for Disease Control and Prevention (CDC), approximately 7,100 new cases of TB were diagnosed in the United States in 2020, and about 13 million Americans are currently living with a dormant TB infection, which means the disease has no outward symptoms.

What Is Tuberculosis?

TB is a bacterial infection that primarily affects the lungs but can spread to other parts of the body. Immediately after infection, the germs that cause TB take up residence in the lungs. Initially, the body’s immune system fights off the infection. In some cases, however, the germs begin to multiply, attacking and destroying healthy lung tissue. From the lungs, TB infection can spread through the bloodstream or lymphatic system to other organs including the bones, kidneys, lymph nodes, skin, spine and, eventually, the brain. With proper treatment TB can be cured. Left untreated, the disease can be fatal.

Types of Tuberculosis

There are two types of TB-related conditions:

• active TB disease, in which TB germs multiply and cause symptoms. An individual with an active infection usually feels sick, can spread the disease to others and requires treatment to prevent serious complications — or even death.
• latent TB infection, in which TB bacteria are alive inside the body, but in a dormant, inactive state. A person with latent TB does not feel sick and cannot spread the germs to others but needs treatment to prevent active TB disease from developing.

Causes of Tuberculosis

TB is caused by the bacterium Mycobacterium tuberculosis. When an infected person sneezes or coughs, droplets containing M. tuberculosis are sent into the air. Another person who breathes in these droplets may become infected, but not everyone exposed to TB bacteria will become sick. According to the CDC, about 5% to 10% of infected individuals will develop active TB disease, sometimes within weeks but possibly years later.

Signs and Symptoms of Tuberculosis

General symptoms of active TB disease include:

• fatigue
• fever and chills
• night sweats
• loss of appetite
• unintended weight loss

Symptoms of active TB disease in the lungs include:

• chest pain
• cough that lasts three weeks or longer
• coughing up blood

How Is Tuberculosis Diagnosed?

• blood test to detect the presence of the tuberculosis bacteria
• tuberculin skin test

Additional tests to confirm if TB infection has advanced to TB disease may include:

• chest X-ray
• mucus analysis

Prevention of Tuberculosis

The bacillus Calmette-Guérin (BCG) vaccine can prevent tuberculosis. While BCG vaccination is not common in the United States, certain people at high risk of TB infection should consider vaccination, including:

• children who are not currently infected and are continually exposed to adults with untreated or uncontrolled TB
• health care workers caring for TB patients or working in other situations where infection is likely

People who are pregnant or immunosuppressed should not receive the vaccine.

Treatments for Tuberculosis

TB bacteria are hard to kill, but the infection can be cured if the treatment plan if followed carefully and completely.

• Latent TB is usually treated with the antibiotic isoniazid (INH) for 6 to 9 months.
• Active TB disease is usually treated with a combination of INH and with three other antibacterial drugs — rifampin, pyrazinamide and ethambutol — for 6 to 12 months.

In addition, regular monitoring is needed to check for TB medication-related liver problems and address any side effects.