It is caused by the organism Mycobacterium tuberculosis . It was estimated that there were over 8 million cases of tuberculosis worldwide in 1992, and 8.8 milllion cases in 1995. Tuberculosis is the leading cause of death worldwide that can be attributed to a single infectious agent. The incidence rate among residents was 48 cases per 100,000 population in 1999 this has fallen from 106 cases per 100,000 population in 1980, and 307 per 100,000 population in 1960. In Singapore, tuberculosis tends to be a disease of older males.
Tuberculosis is a disease with protean manifestations.
Common complaints of patients with pulmonary tuberculosis include chronic cough, fever and expectoration of blood. Patients may not look very ill and many are able to continue working. Other bodily systems may also be affected by tuberculosis. The lymphatic system is one of the more commonly invloved extra-pulmonary sites and patients present with enlarged lymph nodes, most commonly in the neck. The gastro-intestinal tract may also be invloved by the disease.