s: primary and secondary. A. Primary TB Print section In primary TB, a person has become infected with the TB bacteria but often is not aware of it, since this stage of the disease does not produce noticeable symptoms. Primary TB is not contagious in this early stage. Macrophages, immune cells that detect and destroy foreign matter, ingest the TB bacteria and transport them to the lymph nodes where they may be inhibited, destroyed, or they may multiply. If the bacteria multiply, active primary tuberculosis will develop. Symptoms include coughing, night sweats, weight loss, and fever. A chest X ray may show shadows in the lung or fluid collection between the lung and its lining. If the bacteria are inhibited, rather than destroyed, the immune cells and the bacteria form a mass known as a granuloma or tubercle. In effect, the immune cells form a wall around inactive bacteria. As long as the immune system remains strong, the TB bacteria remain walled off and inactive. The tubercle gradually collects calcium deposits to form what is known as a Ghon focus. These initial tubercles in the lung usually heal, leaving permanent scars that appear as shadows in chest X rays. At this initial stage of TB, the disease does not progress, but bacteria may remain dormant in the body for many years. If the immune system becomes weakened, the tubercle opens, releasing the bacteria, and the infection may develop into secondary TB. B. Secondary TB Print section In secondary TB, the formerly dormant bacteria multiply and destroy tissue in the lungs. They also may spread to the rest of the body via the bloodstream. Fluid or air may collect between the lungs and the lining of the lungs, while tubercles continue to develop in the lung, progressively destroying lung tissue. Coughing of blood or phlegm may occur. At this secondary stage, carriers of TB can infect others. III. Diagnosis of Infection and Disease Print section Diagnosis of TB requires two separate m...
