Tuberculosis has an uncanny ability to ensure its own spread and survival. It oftens fools doctors and patients into thinking it is a cold, the flu or bronchitis.
By the time the symptoms--fatigue, loss of appetite, night sweats and the hacking cough most people associate with TB--are correctly diagnosed, others may have been infected, by breathing the bacteria expelled every time the patient coughed or sneezed.
The rod-shaped bacteria, mycobacterium tuberculosis , is minuscule (the average speck of dust is 50 times larger), which makes it ideal for penetrating the innermost reaches of the lungs, though anywhere in the body is susceptible. Pulmonary tuberculosis, which is marked by that terrible cough, occurs in 85% of all patients.
The disease spreads most easily through closed dwellings with little sunlight and poor air circulation--hospital wards, prisons, crowded apartment buildings. Yet TB is not easy to catch. "You have to generally come within a couple of feet of a person who is actively coughing and you usually need to be in that position on a fairly regular basis," says Dr. Gerard Frank, a pulmonary specialist at White Memorial Medical Center in East Los Angeles. And deaths among people who have a regular strain of TB and have treated it are rare. (However, drug-resistant forms of TB are highly fatal.) Nonetheless, according to the latest figures available from the Centers for Disease Control, of 25,701 cases, 1,760 people died in 1990.