Tuberculosis (TB) is a bacterial infection of the lungs, which is caused by the microorganism Mycobacterium tuberculosis. Symptoms may include cough, shortness of breath, pleurisy (inflamed membranes around the lungs), fever, weight loss, night sweats, chills and loss of appetite. The disease can cause serious respiratory problems, which can be life threatening, especially if left untreated.
Tuberculosis is transmitted through airborne droplets. People become infected with TB when they inhale particles of infected sputum from the air. The bacteria become airborne when an infected person expels saliva (when they cough, sneeze, talk, spit, etc.).
About 10 to 15 million Americans have latent TB infections, which means they do not express any symptoms of TB, but they carry the bacterium that causes the disease. These individuals have healthy immune systems that are able to suppress the infection. Only 10% of individuals with latent TB develop the infection.
However, patients who have weakened immune systems, including HIV patients, have an increased risk of developing active TB infections. The risk of developing active TB increases 7-10% in HIV patients who have latent TB. Since HIV patients are immunocompromised, they are more likely to experience symptoms in areas of the body other than the lungs (extrapulmonary TB) than the general population. The disease may affect the bones, joints, nervous system or urinary tract. Also, TB appears to make HIV infection worse.
In 2003, about 11 million people worldwide (nine percent in the United States) were infected with both HIV and TB. Tuberculosis is the leading cause of death among HIV-positive individuals, accounting for 13% of AIDS deaths worldwide. However, in the United States, tuberculosis is a much less common cause of death in HIV/AIDS patients.
HIV-infected patients who have TB usually recover from TB if treatment is started early. Antibiotics are typically prescribed for six to 12 months. The exact drugs and length of treatment varies, depending on the patient's age, overall health and state of the disease (latent or active).
HIV-infected patients are encouraged to have a tuberculin test (TB skin test) each year. If the test is positive, TB is highly suspected. The test cannot determine whether the infection is active or inactive. It also cannot tell the difference between a TB infection and a TB vaccination. Therefore, additional tests, such as a chest X-ray, a sputum culture or both, are usually performed to determine whether the patient has an active TB infection.
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