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Tuberculosis (TB) (Mycobacterium tuberculosis)
1990 Case Definition

Clinical Description

A chronic bacterial infection due to Mycobacterium tuberculosis, characterized pathologically by the formation of granulomas. The most common site of infection is the lung, but other organs may be involved.

Clinical Criteria

A case that meets the following criteria:

  • A positive tuberculin skin test
  • Other signs and symptoms compatible with tuberculosis, such as an abnormal, unstable (worsening or improving) chest x-ray, or clinical evidence of current disease
  • Treatment with two or more antituberculosis medications
  • Completed diagnostic evaluation

Laboratory Criteria for Diagnosis

  • Isolation of M. tuberculosis from a clinical specimen, OR
  • Demonstration of M. tuberculosis from a clinical specimen by DNA probe or mycolic acid pattern on high-pressure liquid chromatography, OR
  • Demonstration of acid-fast bacilli in clinical specimen when a culture has not been or cannot be obtained

Case Classification


A case that is laboratory confirmed or, in the absence of laboratory confirmation, a case that meets the clinical case definition


A case should not be counted twice within any consecutive 12-month period. However, cases in which the patients had verified disease in the past should be reported again if the patients were discharged. Cases also should be reported again if they were lost to supervision for greater than 12 months and disease can be verified again.

Mycobacterial diseases other than those caused by M. tuberculosis should not be counted in tuberculosis morbidity statistics unless there is concurrent tuberculosis.