TB is a contagious or infectious disease that is spread from person-to-person. A person is usually infected by inhaling the germs that have been sprayed into the air by someone with the active disease who coughs. However, inhaling the germ does not usually mean you will develop active disease. A person's natural body defenses are usually able to control the infection so that it does not cause disease. In this case, the person would be infected, but does not have active disease. Only about 10% of those infected will actually develop TB in their lifetimes.
Active disease can occur in an infected person when the body's resistance is low or if there is a large or prolonged exposure to the germs that overcome the body's natural defenses. The body's response to active TB infection produces inflammation that can eventually damage the lungs. The amount of damage may be quite extensive, yet the symptoms may be minimal. The usual symptoms of disease due to TB are: fever, night sweats, cough, loss of appetite, weight loss, blood in the sputum (phlegm), loss of energy.
ough, loss of appetite, weight loss, blood in the sputum (phlegm), loss of energy.
weight loss, blood in the sputum (phlegm), loss of energy.
oss of energy.
To diagnose TB, your health care provider will gather five important pieces of information: symptoms, history of possible exposure and onset of symptoms, Tuberculin skin test or PPD, Chest X-ray, sputum test
ymptoms, history of possible exposure and onset of symptoms, Tuberculin skin test or PPD, Chest X-ray, sputum test
The tuberculin skin test (or PPD) is performed with an extract of killed tuberculosis germs that is injected into the skin. If a person has been infected with tuberculosis, a lump will usually form at the site of the injection-this is a positive test. This generally means that TB germs have infected the body. It does not usually mean the person has active disease. People with positive skin tests but without active disease cannot transmit the infection to others.
If a person has been infected with TB, but active disease has not developed, the chest X-ray usually will be normal. Most people with a positive PPD have normal chest X-rays and continue to be healthy. For such people, preventive medication may be recommended to eliminate the latent (non-contagious) infection. However, if the germ has attacked and caused inflammation in the lungs, an abnormal shadow is usually visible on the chest X-rays. For these people, diagnostic tests (sputum tests) and treatment usually are appropriate.
Samples of sputum coughed up from the lungs can be tested to see if TB germs are present. The sputum is examined under a microscope (a "sputum smear") to look for evidence of the presence of TB organisms. The organisms are then grown in the laboratory to identify them as TB germs and to determine what medications are effective in treating them. These studies are referred to as culture and susceptibility testing. State health department laboratories and reference laboratories can perform such testing.
People with a positive tuberculin skin test may or may not receive preventive medication therapy depending on the exposure history, the timing of the skin test conversion (when the test changes from negative to positive) and other factors in the person's medical history. When it is known that a person has recently been in close contact with someone with active tuberculosis and has developed a positive tuberculin skin test, preventive treatment is advisable due to a high risk of developing active disease. Isoniazid (INH) may be prescribed for nine months as preventive treatment.
Since the advent of anti-TB medications in the 1940s, the treatment of drug-susceptible tuberculosis has become highly effective if administered and taken properly. Treatment no longer requires prolonged hospital stays. In many cases, a person with a new case of TB can be treated at home. Others will enter the hospital to be placed on a medication program and to be isolated until the disease is controlled. When the person is no longer infectious, he or she can leave the hospital and continue on medication at home. Hospitalization in such cases may be a few weeks to several months depending on the severity of the disease and the effectiveness of the treatment program.
In most cases, a treatment program for drug-susceptible TB involves taking two or four medications for a typical period of six months. Medications may include isoniazid, rifampin, pyrazinamide and ethambutol. It is necessary to take multiple medications and to take all of the doses prescribed, because all of the TB germs cannot be eliminated by one medication.
It is important to realize that hospitalization for a person with TB, when necessary, represents only the beginning of treatment. Since active TB is slow to respond completely to therapy, prescribed medications must be taken faithfully for a long period of time (at least 6 months). If the TB medications are not taken regularly, serious complications may develop including:
There is a high risk of disease persistence or recurrence.
Given the many effective medications available today, the chances are excellent that a person with tuberculosis can be cured. It is important, however, for the person to understand the disease and to cooperate fully in the therapy program.
Source: National Jewish Research Hospital, 2004