Though the bacteria usually attack the lungs, tuberculosis can affect the brain, back, knee, lymph nodes and bones. A positive skin test does not mean a person has active tuberculosis. About 90 percent of people with a positive skin test won't develop active tuberculosis for years, but people with diabetes, HIV infection, or other risk factors may develop active tuberculosis. After a patient has a positive skin test, a doctor usually will recommend a chest X-ray to determine if the patient has active tuberculosis. Even if the X-ray is negative, the Department of Public Health recommends that people with positive skin tests take a course of antibiotics to prevent the disease from developing later in life.
Tuberculosis is a contagious disease.
Only people who are sick with active pulmonary tuberculosis are infectious. When infectious people cough, sneeze, talk or spit, they propel tuberculosis germs, known as bacilli, into the air. A person needs to inhale only a small number of bacilli to be infected. The most common symptoms of active pulmonary tuberculosis are a persistent cough that does not go away, unexplained weight loss, low-grade fever, night chills, coughing up blood, and loss of appetite. Tuberculosis is treated with a course of antibiotics, usually taken for many months.