Backgrounder on Tuberculosis

Pathogen:

Mycobacterium tuberculosis is a thin, slightly curved bacillus (rod-shaped bacterium). Its cell wall incorporates a number of lipids and proteins, making M. tuberculosis extremely hardy. Left in the dark, it can survive as long as six to eight months in sputum.

Route of infection:

Through airborne droplets containing the bacterium and released into the air by the coughing, sneezing, or spitting of a tuberculosis patient.

Tuberculosis symptoms:

M. tuberculosis multiplies quite slowly, and during the initial stages of infection a typical person will not show any obvious symptoms or experience discomfort. Once the disease becomes active, fatigue, loss of appetite, unexplained weight loss, afternoon fevers, night sweats, back pain, coughing, insomnia, cardiac arrhythmia, and-in serious cases-the coughing up of blood and chest pain may occur.

Susceptible organs:

Tuberculosis typically affects the lungs (about 90% of cases), but besides lung tissue, M. tuberculosis can also invade other body tissues, especially those that are oxygen-rich, such as in the kidneys, the meninges (the membranes that enclose the brain), and bone tissues in children. In Taiwan, the most commonly seen non-pulmonary forms of tuberculosis affect the lymphatic system and the bones.

Non-pulmonary tuberculosis is not infectious and is usually not easily discovered. However, it may cause considerable damage to the body. For example, bone tuberculosis can result in bone softening, degeneration, or deformation.

Types:

Pulmonary tuberculosis patients can be divided into active (roughly 10% of the total) and latent. Active patients are those whose sputum contains M. tuberculosis and who are therefore infectious, while latent patients are not.

High-risk groups:

Aborigines, the homeless, elderly people in nursing homes, and people with chronic diseases, are all high-risk groups for tuberculosis in Taiwan, showing rates of infection and active disease ten times higher than in the general population.

How can tuberculosis be prevented?

After a tuberculosis victim has completed the treatment course, he does not possess immunity to tuberculosis and has the same chance of infection as the general population. Therefore, avoiding damp, dimly lit, unsanitary areas, as well as congregations of people at close quarters where there may be contact with airborne droplets of sputum, maintaining good general fitness, and strengthening the immune system are essential for preventing infection.

(Chang Chiung-fang/tr. by Minn Song)