Tuberculosis (TB) infection can develop after breathing in droplets sprayed into the air from a cough or sneeze by someone infected with the Mycobacterium tuberculosis bacterium. The resulting lung infection is called primary TB.
The usual site of TB is the lungs (pulmonary TB), but other organs can be involved. In the United States, most people with primary tuberculosis get better and have no further evidence of disease. Disseminated TB develops in the small number of infected people whose immune systems do not successfully contain the primary infection.
Disseminated disease can occur within weeks of the primary infection. Sometimes, it does not occur until years after you become infected. You are more likely to get this type of TB if you have a weakened immune system due to disease (such as AIDS) or certain medicines. Infants and older adults are also at higher risk.
Your risk of catching TB increases if you:
- Are around people who have the disease (such as during overseas travel)
- Live in crowded or unclean conditions
- Have poor nutrition
The following factors can increase the rate of TB infection in a population:
- Increase in HIV infections
- Increase in number of homeless people with unstable housing (poor environment and nutrition)
- The appearance of drug-resistant strains of TB
Disseminated tuberculosis is a contagious mycobacterial infection in which mycobacteria have spread from the lungs to other parts of the body through the blood or lymph system.
Exams and Tests
The health care provider will perform a physical exam. This may show:
Tests that may be ordered include:
- Biopsies and cultures of affected organs or tissues
- Bronchoscopy for biopsy or culture
- Chest x-ray
- CT scan of the affected area
- Fundoscopy may reveal retinal lesions
- Interferon-gamma release blood test, such as the QFT-Gold test to test for prior exposure to TB
- Lung biopsy
- Mycobacterial culture of bone marrow or blood
- Pleural biopsy
- Tuberculin skin test (PPD test)
- Sputum examination and cultures
Most forms of disseminated TB respond well to treatment. The tissue that is affected, such as the bones or joints, may have permanent damage due to the infection.
Complications of disseminated TB can include:
Medicines used to treat TB can cause side effects, including:
- Changes in vision
- Orange- or brown-colored tears and urine
- Liver inflammation
A vision test may be done before treatment so your doctor can monitor any changes in the health of your eyes.
TB is a preventable disease, even in those who have been exposed to an infected person. Skin testing 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. It does not mean that you have active disease or are contagious. 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 vaccination (called BCG) to prevent TB. 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 provider.
Disseminated tuberculosis can affect many different body areas. Symptoms depend on the affected areas of the body and can include:
The goal of treatment is to cure the infection with medicines that fight the TB bacteria. Treatment of disseminated TB involves a combination of several medicines (usually 4). All medicines are continued until lab tests show which work best.
You may need to take many different pills for 6 months or longer. It is very important that you take the pills the way your provider instructed.
When people do not take their TB medicines as instructed, the infection can become much more difficult to treat. The TB bacteria can become resistant to treatment. This means the medicines no longer work.
When there is concern that a person may not take all the medicines as directed, a provider may need to watch the person take the prescribed medicines. This approach is called directly observed therapy. In this case, medicines may be given 2 or 3 times a week, as prescribed by a provider.
You may need to stay at home or be admitted to a hospital for 2 to 4 weeks to avoid spreading the disease to others until you are no longer contagious.
Your provider may be required by law to report your TB illness to the local health department. Your health care team will ensure that you receive the best care.
When to Contact a Medical Professional
Call your provider if you know or suspect that you have been exposed to TB. All forms of TB and exposure need prompt evaluation and treatment.
Ellner JJ. Tuberculosis. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 324.
Fitzgerald DW, Sterling TR, Haas DW. Mycobacterium tuberculosis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 251.