Pulmonary tuberculosis (TB) is a contagious bacterial infection that mainly involves the lungs, but may spread to other organs.

Pulmonary tuberculosis is caused by a bacteria called Mycobacterium tuberculosis (M. tuberculosis). You can get tuberculosis by breathing in air droplets from a cough or sneeze of an infected person.

The primary stage of the infection is usually asymptomatic (without symptoms). In the United States, most people will recover from primary TB infection without further evidence of the disease. However, in some cases, the disease may become active within weeks after the primary infection, or it may lie dormant for years and later reappear.

The following are at higher risk for active TB:

• Elderly
• Infants
• Persons with weakened immune systems, for example due to AIDS, chemotherapy, or antirejection medicines given after a organ transplant

Your risk of contracting TB increases if you:

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

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

• Increase in HIV infections
• Increase in number of homeless individuals (poor environment and poor 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 class.

See also:

• Disseminated tuberculosis (affects the whole body)
• Atypical mycobacterial infection

• Limited to minor cough and mild fever, if apparent
• Fatigue
• Unintentional weight loss
• Coughing up blood
• Fever and night sweats
• Phlegm-producing cough

Additional symptoms that may be associated with this disease:

• Wheezing
• Excessive sweating, especially at night
• Chest pain
• Breathing difficulty

Examination of the lungs by stethoscope can reveal crackles (unusual breath sounds). Enlarged or tender lymph nodes may be present in the neck or other areas. Fluid may be detectable around a lung. Clubbing of the fingers or toes may be present.

Tests may include:

• Chest x-ray
• Sputum cultures
• Tuberculin skin test
• Bronchoscopy
• Thoracentesis
• Chest CT
• Interferon-gamma blood test such as the QFT-Gold test
• Biopsy of the affected tissue (rare)

The goal of treatment is to cure the infection with drugs that fight the tuberculosis bacteria. The intial treatment may involve a combination of many drugs. It is continued until lab tests show which medicine works best.

Treatment usually lasts for 6 months, but longer courses may be needed for persons with AIDS or whose disease responds slowly.

You may need to be admitted to a hospital to prevent the spread of the disease to others until you are no longer contagious.

Incomplete treatment of TB infections (such as failure to take medications for the prescribed length of time) can contribute to the emergence of drug-resistant strains of bacteria.

The stress of illness may be helped by joining a support group where members share common experiences and problems.

See: Lung disease - support group

Symptoms may improve in 2 to 3 weeks. A chest x-ray will not show this improvement until later. Prognosis is excellent if pulmonary TB is diagnosed early and treatment is begun.

Pulmonary TB can cause permanent lung damage if not treated early.

Medicines used to treat TB may cause side effects, including non-infectious hepatitis and an orange or brown coloration of tears and urine.

Call your health care provider if you have been exposed to tuberculosis, or if symptoms of TB develop.

Call your health care provider if symptoms persist despite treatment.

Also call if new symptoms develop, including indications that complications are developing.

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 individuals who may have been exposed to TB, such as health care workers.

A positive skin test indicates prior TB exposure. Preventive therapy should be discussed with your doctor. Individuals exposed to tuberculosis should be skin tested immediately and a follow-up test should be done at a later date, if the initial test is negative.

Prompt treatment is extremely important in controlling the spread of tuberculosis for those who have already progressed to active TB disease.

A BCG vaccination to prevent TB is given in some countries with a high incidence of TB, but its effectiveness remains controversial. It is not routinely used in the United States. People who have had BCG may still be skin tested for TB and results of testing (if positive) discussed with one's doctor.

Ferrara G, Losi M, Meacci M, et al. Routine Hospital Use of a New Commercial Whole Blood Interferon-(gamma) Assay for the Diagnosis of Tuberculosis Infection. Am J Respir Crit Care Med. 2005 Sep 1;172(5):631-5. Epub 2005 Jun 16.

US Centers for Disease Control. Treatment of Tuberculosis. MMWR 2003; 52.

Diagnostic Standards: Classification of TB in Adults and Children. Am J Respir Crit Care Med 2000; 161.