Tuberculosis (patient information)

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-in-Chief: Ethan Leeman

Overview

Tuberculosis, or TB is a bacterial infection that kills 3 million people worldwide, more people than any other infection in the world. Approximately one-third of the world is infected, and 15 million people in the US. Active tuberculosis kills 60% of the time if not treated, but treatment cures 90% of patients. Most people are infected with TB have latent TB. This means that the bacteria is controlled by the body's immune system. People with latent TB do not have symptoms and cannot transmit TB to other people. However, later if the infected person has a weakened immune system (AIDS, young children, elderly, sick with other diseases, etc.), the bacteria can break out leading to active TB, or TB disease.

What are the symptoms of Tuberculosis?

Latent TB is held in the alveoli of the lungs. As active TB develops, the bacteria spreads out from the alveoli to the lungs and then to other organ systems, killing cells and making granulomas. As a result, depending on what organ system is affected, the symptoms can be very different. The primary stage of TB usually doesn't cause symptoms. When symptoms of pulmonary TB occur, they may include:

• Cough (usually cough up mucus)
• Coughing up blood
• Excessive sweating, especially at night
• Fatigue
• Fever
• Unintentional weight loss

Other symptoms that may occur with this disease:

• Breathing difficulty
• Chest pain
• Wheezing

Diagnosis

Latent Tuberculosis can be detected about 6-8 weeks after exposure. A common test is a skin test, where substance called PPD, is injected underneath the forearm. If a red welt forms at the injection site, they may have Latent or Active TB. Latent TB is sometimes called PPD-positive. Diagnosing active TB can be done with a combination of symptoms, patient history (any known exposure to TB), TB tests, and x-rays. X-rays of the lungs often show can show cavities or legions that are typical of TB. People should contact their doctor and get test if they:

• Have spent time with a known or suspected person affected with TB
• Have HIV or another immuno-compromising condition
• Have symptoms of active TB
• Are from a country where TB is common (Most of Latin America, Caribbean, Africa, Asia, Eastern Europe, and Russia)
• Live somewhere where active TB is more common (homeless shelter, jail, nursing homes, etc.)
• Inject illegal drugs

Who is at highest risk?

Tuberculosis is spread from person to person through the air as person with active tuberculosis coughs or sneezes. Tuberculosis is not often spread on surfaces or by objects of a person infected with active tuberculosis, or by:

• Shaking hands
• Sharing food
• Kissing
• Sharing toothbrushes

The following people are at higher risk for active TB:

• Elderly
• Infants
• People with weakened immune systems, for example due to AIDS, chemotherapy, diabetes, or certain medications

Your risk of contracting TB increases if you:

• Are in frequent contact with people who have TB
• Have poor nutrition
• Live in crowded or unsanitary living conditions

The following factors may increase the rate of TB infection in a population:

• Increase in HIV infections
• Increase in number of homeless people (poor environment and nutrition)
• The appearance of drug-resistant strains of TB

Treatment

Typical treatment involves one or a few antibiotics for months. TB is notorious for having a lengthy treatment procedure. After two weeks of treatment, people are typically no longer contagious. Some of the medications given for TB have some negative side effects, especially in combination with other drugs. For these reasons, some patients find it very difficult to take their medicine for the necessary duration. However, doing so may make the bacteria resistant to the antibiotics and make treatment even more difficult in the future. Treatment for multi-drug-resistant tuberculosis or extensively drug-resistant TB have different treatments with far worse prognosis.

Prevention

On an individual basis, covering coughs and sneezes does reduce transmission. On a larger scale, adequate ventilation and reduction of crowded areas can also reduce transmission. As with all infectious diseases, earlier identification of the disease is necessary to prevent spreading. A prophylactic antibiotic INH can cure latent TB before it progresses to active TB, and should be given to people who:

• Have latent TB
• Are close contact with known infected patients
• Live in countries where TB is prevalent.
• Are at risk of TB infection

A vaccine called BCG prevents the spread of TB to other parts of the body but not infection. It is recommended just for infants in countries known to have high levels of TB. It is not recommended for overall use in the US. BCG is known to interfere with TB skin tests, giving false positives, and other tests are needed to test for TB in these cases.

Sources

• NLM
• CDC