Pulmonary tuberculosis (TB) is a contagious bacterial infection that involves the lungs, but may spread to other organs.
TB; Tuberculosis - pulmonary
Causes, incidence, and risk factors
Pulmonary tuberculosis (TB) is caused by the bacteria Mycobacterium tuberculosis (M. tuberculosis). You can get TB by breathing in air droplets from a cough or sneeze of an infected person. This is called primary TB.
In the United States, most people will recover from primary TB infection without further evidence of the disease. The infection may stay inactive (dormant) for years. However, in some people it can reactivate.
Most people who develop symptoms of a TB infection first became infected in the past. However, in some cases, the disease may become active within weeks after the primary infection.
The following people are at higher risk for active TB:
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
In the United States, there are approximately 10 cases of TB per 100,000 people. However, rates vary dramatically by area of residence and socioeconomic status.
The goal of treatment is to cure the infection with drugs that fight the TB bacteria. Treatment of active pulmonary TB will always involve a combination of many drugs (usually four drugs). All of the drugs are continued until lab tests show which medicines work best.
The most commonly used drugs include:
Other drugs that may be used to treat TB include:
You may need to take many different pills at different times of the day for 6 months or longer. It is very important that you take the pills the way your health care provider instructed.
When people do not take their TB medications as recommended, the infection may become much more difficult to treat. The TB bacteria may become resistant to treatment, and sometimes, the drugs no longer help treat the infection.
When there is a concern that a patient may not take all the medication as directed, a health care provider may need to watch the person take the prescribed drugs. This is called directly observed therapy. In this case, drugs may be given 2 or 3 times per week, as prescribed by a doctor.
You may need to stay at home or be admitted to a hospital for 2 - 4 weeks to avoid spreading the disease to others until you are no longer contagious.
Your doctor or nurse is required by law to report your TB illness to the local health department. Your health care team will be sure that you receive the best care for your TB.
You can ease the stress of illness by joining a support group where members share common experiences and problems.
Symptoms often improve in 2 - 3 weeks. A chest x-ray will not show this improvement until weeks or months later. The outlook is excellent if pulmonary TB is diagnosed early and treatment is begun quickly.
Pulmonary TB can cause permanent lung damage if not treated early.
Medicines used to treat TB may cause side effects, including liver problems. Other side effects include:
Changes in vision
Orange- or brown-colored tears and urine
A vision test may be done before treatment so your doctor can monitor any changes in your eyes' health over time.
Calling your health care provider
Call your health care provider if:
You have been exposed to TB
You develop symptoms of TB
Your symptoms continue despite treatment
New symptoms develop
TB is a preventable disease, even in those who have been exposed to an infected person. Skin testing (PPD) for TB is used in high risk populations or in people who may have been exposed to TB, such as health care workers.
People who have been exposed to TB should be skin tested immediately and have a follow-up test at a later date, if the first test is negative.
A positive skin test means you have come into contact with the TB bacteria. Talk to your doctor about how to prevent getting tuberculosis.
Prompt treatment is extremely important in controlling the spread of TB from those who have active TB disease to those who have never been infected with TB.
Some countries with a high incidence of TB give people a BCG vaccination to prevent TB. However, the effectiveness of this vaccine is limited and it is not routinely used in the United States.
People who have had BCG may still be skin tested for TB. Discuss the test results (if positive) with your doctor.
Fitzgerald DW, Sterling TR, Haas DW. Mycobacterium tuberculosis. In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Orlando, FL: Saunders Elsevier; 2009:chap 250.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.