What Is Tuberculosis?
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Medically reviewed by Brian H Wetchler, DO
Tuberculosis (TB) is a curable, contagious bacterial disease that primarily affects the lungs. With treatment, the outcome for TB is good. However, 1.5 million people around the world die from tuberculosis each year. According to the World Health Organization, it is the world’s most deadly infectious disease.
In the United States, western Europe, and other high-income areas, TB disease rates are very low. It is most common in sub-Saharan Africa, Eastern Europe, and Asia.
Here’s what you need to know about the stages of tuberculosis infection, how it’s treated, and what it means for your health.
Types
Once the bacteria that causes TB enters the lungs, it may stay dormant for a period of time, or it may cause disease in a matter of weeks. When the bacteria lie dormant, it is known as a latent TB infection. When the bacteria become active in your system, it's called active TB disease.
Latent TB Infection
In most cases, the TB bacteria stays dormant in the lungs. People who have a latent infection don’t show any symptoms of TB and aren’t contagious. Sometimes, an individual’s immune system is able to fight off the infection completely and clear the bacteria from the body.
If the immune system never clears the bacteria, it can stay dormant for months or even years before becoming an active infection.
Most people with latent TB recover without having any symptoms of the disease.
Active TB Disease
In some cases, the immune system isn’t able to fight off the bacteria. That’s when a case of dormant TB infection becomes active TB disease.
Only 5-10% of people who contract the bacteria will develop symptomatic TB disease. People with compromised immune systems are most at risk of developing active TB.
If you have TB disease, you’ll likely show symptoms such as fever and weight loss. Some people may remain asymptomatic, which is why it’s important to get a TB test if you think you’ve been exposed.
The most common type of active TB is pulmonary TB, which means it causes disease in the lungs. However, TB disease can spread to other parts of the body, such as the kidneys, liver, and brain.
Multidrug-Resistant TB
Some strains of TB have evolved to become resistant to some of the most common antimicrobial drugs used to treat TB disease. This is called multidrug-resistant (MDR) TB. Drug resistance means that certain drugs are no longer effective against the bacteria.
A non-resistant infection can turn into MDR TB. This occurs when TB bacteria are exposed to drugs used for treatment but the infection isn't completely eradicated (such as during uncompleted treatments). Drug-resistant strains are also spread between people, just like other strains of TB. Cases of MDR TB are more difficult to treat.
In rare cases, a TB infection can become extensively drug-resistant, which means it is resistant to all of the most effective drugs for the disease.
Tuberculosis Symptoms
While a latent TB infection is asymptomatic, TB disease can cause a range of symptoms. These include:
Cough
Chest pain
Fever
Night sweats
Weight loss
In some cases, the symptoms can remain mild for months.
If you have a latent TB infection, it’s important to understand the symptoms of TB disease. If you think you’re experiencing symptoms, contact a healthcare provider right away.
One of the most well-known symptoms of TB is coughing up blood and thick sputum. However, not all people with tuberculosis report that symptom. Some people show no symptoms at all.
What Causes TB?
TB is spread when the bacteria Mycobacterium tuberculosis enters the lungs, usually through person-to-person contact. The most common way TB spreads is through aerosolized droplets when someone coughs, laughs, talks, or even breathes. Therefore, TB can spread especially easily in small, crowded spaces, such as nursing homes, prisons, or shelters for unhoused people.
Though most people never become sick from TB, there are some communities that are more at risk. People at a higher risk of developing TB disease include people who:
Have a medical condition that affects the immune system
Are undergoing certain treatments
Are malnourished
Are either under the age of 5 or very elderly
Are experiencing homelessness
Live in crowded conditions
According to 2021 data from the World Health Organization (WHO), alcohol use disorder was the top reason why people in the United States fell ill with tuberculosis, following smoking and human immunodeficiency virus (HIV).
Diagnosis
There are two main ways to test for tuberculosis. The method used depends on whether the infection is dormant or if it has progressed to active TB disease:
Skin test: A skin test can tell you and your healthcare provider if you have TB, but it doesn’t differentiate between latent TB and TB disease. During a TB skin test, a healthcare provider will inject a liquid called tuberculin into your arm. After several days, they will check for a reaction.
Blood test: During a TB blood test, your healthcare provider will take a sample of your blood and send it to a lab.
After a positive TB blood or skin test, your healthcare provider will perform more testing to confirm if you have TB disease. These tests may include:
Chest X-ray: An imaging test used to look at the organs inside your chest
Chest CT scan: An imaging test similar to an X-ray that creates a 3-dimensional visualization of the organs inside your chest
Bronchoscopy: A procedure that uses a small camera inserted into your throat through your mouth so your healthcare provider can look at your airways
Sputum smear: This test examines your sputum (a mixture of your saliva and mucus) to look for TB bacteria
Tissue biopsies: Your healthcare provider takes a small sample of your lung tissue to test for the presence of TB bacteria
Who Treats Tuberculosis?
Because tuberculosis is both an infectious disease and a lung (pulmonary) disease, it can be treated by an infection disease specialist, a pulmonologist, or an internist (a primary care doctor who treats adults with acute or chronic conditions).
Treatments for Tuberculosis
With treatment, TB is almost always curable. However, without treatment, the prognosis is much worse: Half of people with untreated TB disease die from it.
Treatment for Latent Infection
If you have latent TB infection, it’s important to undergo treatment or it can progress to an active case of TB disease. According to the CDC, 80% of TB disease cases in the United States progressed from an untreated latent TB infection.
If you have Latent TB, your doctor may prescribe a regimen of one or two TB drugs to be taken for 3-4 months. The medications used to treat latent TB include:
Hydra, Hyzyd, and Isovit (isoniazid)
Priftin (rifapentine)
Rifadin and Rimactane (rifampin)
Treatment for TB Disease
The treatment for TB disease—when taken exactly as directed—is effective at curing it, especially if you start it quickly.
Treatment for active TB disease usually comprises a combination of antibiotic drugs, including:
Hydra, Hyzyd, and Isovit (isoniazid)
Priftin (rifapentine)
Avelox (moxifloxacin)
Rifadin and Rimactane (rifampin)
Rifater, Rimstar, and Voractiv (pyrazinamide)
Myambutol (ethambutol)
Depending on the combination of drugs your healthcare provider recommends, the treatment can take anywhere from 4-9 months. For the treatment to be successful, you’ll need to take each drug exactly as directed by your prescribing healthcare provider and complete the entire course of treatment.
After several weeks of treatment, your symptoms will start to subside and your provider will be able to tell you when you are no longer contagious.
Treatment for MDR TB
If TB disease is left untreated, or the affected person doesn’t adhere to their treatment, TB can evolve to become resistant to some or all of the standard TB drugs. If you’re diagnosed with MDR TB, it will likely be a much longer treatment regimen—up to 30 months.
Side Effects
Many of the drugs that treat TB can take a toll on your body. Some of the side effects associated with TB treatment include:
Nausea or vomiting
Lack of appetite
Orange-colored body fluids
Changes in vision
Liver inflammation
If you are undergoing treatment for MDR TB, you may experience more or worse side effects, including:
Psychiatric disorders
Hearing loss
Joint pain
Kidney damage
If you experience any serious side effects, contact your healthcare provider immediately.
Managing TB Treatment
Successful TB treatment involves keeping up with multiple drugs over an extended period of time.
Some people use medicine trackers, such as those available from the CDC, to help them keep up with their regimen.
You can also get something called directly observed therapy (DOT), which is when a healthcare worker meets with you to administer your medicine and keep track of your treatment.
How to Prevent TB
If you are at high risk for developing TB disease and you’ve traveled abroad or been in an environment where you might have been exposed, it’s important to get tested for TB. If you do have latent TB, prompt treatment can keep you from developing active TB disease.
If you have TB disease, you should listen to your healthcare provider's recommendations about how long you should avoid being around people to keep from spreading the infection. Some states may have laws requiring you to isolate until you’re no longer contagious.
There is no vaccine available that fully protects against TB infection. However, scientists around the world are working to create a safe and effective TB vaccine.
Complications
Dangerous complications can occur as a result of TB disease, especially if you have one or more comorbidities or leave the disease untreated.
People with HIV are particularly at risk for both contracting TB and developing TB disease. The outcome is also statistically worse. TB is the leading cause of death of people with HIV.
Other factors associated with complications and worse treatment outcomes include:
Alcohol use
Smoking
Malnutrition
Depression
When left untreated, TB disease can lead to:
Drug-resistant TB
Lung damage
Acute respiratory distress syndrome, where fluid builds up in the tiny air sacs of your lungs
TB disease can spread through the bloodstream to other organs like the kidneys, spinal cord, or brain.
A Quick Review
Tuberculosis (TB) is a lung infection that spreads through the air when someone who has it coughs or sneezes. It causes symptoms like coughing, chest pain, fever, fatigue, and weight loss. TB is diagnosed through tests like chest X-rays and treated with antibiotics for several months. It's important to take all the prescribed medicine to prevent it from becoming drug-resistant.
TB is still a significant health problem worldwide, with many new cases every year. Efforts to control it include vaccines, better testing and treatment, and keeping healthcare settings clean. Getting diagnosed and treated early is crucial because TB can be cured with the right treatment but becomes more challenging to treat if it's not caught early.
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