Tuberculosis (TB)

Table 5. Definitions of tuberculosis cases and treatment outcomes

A. Definitions of tuberculosis cases

Case of tuberculosis

A patient in whom tuberculosis has been confirmed by bacteriology or diagnosed by a clinician.

Definite case

A patient with positive culture for the Mycobacterium tuberculosis complex. In countries where culture is not routinely available, a patient with two sputum smears positive for acid-fast bacilli (AFB+) is also considered a definite case.

Pulmonary case

A patient with tuberculosis disease involving the lung parenchyma.

Smear-positive pulmonary case

A patient with at least two initial sputum smear examinations (direct smear microscopy) AFB+; or one sputum examination AFB+ and radiographic abnormalities consistent with active pulmonary tuberculosis as determined by a clinician; or one sputum specimen AFB+ and culture positive for M. tuberculosis.

Smear-negative pulmonary case

A patient with pulmonary tuberculosis not meeting the above criteria for smear-positive disease. Diagnostic criteria should include: at least three sputum smear examinations negative for AFB; and radiographic abnormalities consistent with active pulmonary tuberculosis; and no response to a course of broad-spectrum antibiotics; and a decision by a clinician to treat with a full course of antituberculosis chemotherapy; or positive culture but negative AFB sputum examinations.

Extrapulmonary case

A patient with tuberculosis of organs other than the lungs (e.g. pleura, lymph nodes, abdomen, genitourinary tract, skin, joints and bones, meninges). Diagnosis should be based on one culture-positive specimen, or histological or strong clinical evidence consistent with active extrapulmonary disease, followed by a decision by a clinician to treat with a full course of antituberculosis chemotherapy. A patient in whom both pulmonary and extrapulmonary tuberculosis has been diagnosed should be classified as a pulmonary case.

New case

A patient who has never had treatment for tuberculosis or who has taken antituberculosis drugs for less than one month.

Relapse case

A patient previously declared cured but with a new episode of bacteriologically positive (sputum smear or culture) tuberculosis.

Re-treatment case

A patient previously treated for tuberculosis, undergoing treatment for a new episode, usually of bacteriologically-positive tuberculosis.

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