Method of Diagnosis Clinical presentation. Tuberculin skin test, using the Mantoux procedure. Radiographic examination, sometimes including CT scans. Recovery and identification of mycobacterium from specimens has been made more rapid with test procedures such as the Bactec Systems and DNA probes. Mode of Transmission Infection occurs primarily by inhalation of aerosols produced by persons with pulmonary or laryngeal tuberculosis during coughing and sneezing.
Bovine tuberculosis results mainly from ingestion of unpasteurised milk and dairy products.
Theoretically the patient is infectious as long as viable bacilli are being discharged from the sputum. In practice the greatest risk of transmitting infection is in the period prior to diagnosis of an open case. A sputum smear positive case is more infectious than a culture positive case. The risk of transmitting the infection is significantly reduced within a period which can be from days to two weeks after commencing appropriate chemotherapy. Special Groups at Risk Immigrants and refugees from countries with a high incidence of tuberculosis.