The differences are as follows:
- Dormant (Latent) TB: Dormant TB is characterized by a positive TB skin test, a normal chest x-ray, and no symptoms. There are most likely only a few TB germs in an inactive state and the individual is not contagious. Nevertheless, treatment with an antibiotic may be recommended for this person to prevent the TB from turning into an active infection. The antibiotic used for this purpose is called isoniazid (INH). If taken for 6 to 12 months, it will prevent the TB from becoming active in the future. If a person with a positive skin test does not take INH, there is a 5 to 10% lifelong risk that the TB will become active.
- Active TB: Active TB is characterized by a positive skin test along with an abnormal chest x-ray and sputum evidencing TB bacteria. The individual is contagious. Active TB is usually accompanied by symptoms such as cough, fever, weight loss, and fatigue. Treatment is with a combination of medications along with isoniazid (INH). Rifampin (Rifadin), ethambutol (Myambutol), and pyrazinamide are the drugs commonly used to treat active TB in conjunction with INH. Streptomycin, a drug that is given by injection, may be used as well, particularly when the disease is extensive and/or the patients do not take their oral medications reliably (poor compliance). Treatment usually lasts for many months and sometimes, years. Successful treatment is dependent largely on the compliance of the patient. Failure to take the medications is the most important cause of failure to cure TB infection.
Surgery on the lungs may be indicated to help cure TB when medication has failed, but in this day and age, surgery for TB is unusual. Treatment with appropriate antibiotics will usually cure the TB. Without treatment, however, tuberculosis can be a lethal infection.
See also: Tuberculous meningitis.