Both the 1994 CDC guidelines on tuberculosis control for health care facilities and the 1997 proposed OSHA rule on tuberculosis control emphasize the fact that prompt identification, isolation, and treatment of people with infectious tuberculosis is critical to an effective tuberculosis control program. Following several outbreaks of tuberculosis in hospitals and other settings, CDC, OSHA, state health departments, and others initiated educational programs to make physicians, nurses, and others more aware of the symptoms of infectious tuberculosis. Nonetheless, as described below, prompt identification of infectious tuberculosis is complicated because symptoms are not highly specific to the disease.
According to CDC’s case reporting requirements (CDC, 1999b), a laboratory definition of a case of tuberculosis requires either the isolation of M. tuberculosis from a clinical specimen or demonstration of acid-fast bacilli in a clinical specimen when a culture was not or could not be obtained. (The processing of laboratory smears of sputum or some other specimen uses a dye that leaves only mycobacteria colored after processing with an acid-alcohol solution. The bacteria are thus often described as acid-fast bacilli [AFB] and the smears as AFB positive or negative.) The clinical case definition of tuberculosis requires all of the following: a positive tuberculin skin test result, other signs and symptoms compatible with active tuberculosis (e.g., abnormal and unstable radiologic findings and persistent cough), treatment with two or more antituberculous medications, and a completed diagnostic evaluation. This clinical definition is for reporting purposes. Physicians may begin treatment of individuals with suspected infectious tuberculosis on the basis of symptoms and risk factors while awaiting test results.
Common symptoms of pulmonary tuberculosis include chronic cough, a cough that produces sputum, chest pain associated with coughing, and less commonly, coughing up of blood. Other symptoms, which also appear in nonpulmonary tuberculosis, include fever, weight loss, night sweats, and fatigue. Some people with infectious tuberculosis report less specific symptoms or, rarely, no symptoms. The higher the prevalence of active tuberculosis in the community, the higher “the index of suspicion” should be that those with symptoms warrant further evaluation.
Diagnostic evaluation of someone suspected of having active tuberculosis involves