Overview of tuberculosis

Tuberculosis is one of the major causes of mortality and morbidity in developing countries and the stigma associated with the disease further compound the problem. Tuberculosis is classifies as an infectious disease which is caused by micro organisms called mycobacterium tuberculosis. Occurrence of tuberculosis is world-wide. In industrialized countries, due to resource, high standards of living and widespread chemotherapy the disease have shown downward trends, but in developing countries it remains a big problem as ever (WHO, 1996).

The World Health Organization (WHO) estimates that there are about 16-20 million of tuberculosis cases worldwide. Up to 90 million will develop the disease in the next decade; there are approximately 8 million new smear positive cases annually with a majority (about 95%) from developing countries.

In addition 3 million tuberculosis patients die each year, the majority of them in developing countries 30 million more people will/may die from tuberculosis in the decade. The greatest burden of tuberculoses incidence and mortality occurs in the productivity age group 15 to 45 years with obvious consequences.

In Nigeria it is estimated that there are 100,000 new sputum positive cases each year, given that the estimated annual risk of infection of Tuberculosis in Nigeria is approximately 2%, about 200,000 cases of all types of Tuberculosis occur annually.

All ages from infants are affected, individual between 15 to 35 years of age are mostly affected, both sexes are affected but there are more males than females due to epidemiological differences. According to WHO (1993), females have a higher resistance of progression from infection to disease as compared with males. The source of infection is a person with Tuberculosis of the lungs who is coughing, transmission occurs by airborne spread of infectious droplet coughing, singing or sneezing produces tiny droplet one cough may produce 3,000 droplet nuclei.

An individual’s risk of infection depends on the extent of exposure to droplet nuclei and his susceptibility to infection, prolonged closed exposure to an infectious case may lead to infection of contacts. An infected person stays infected for many years probable for life, a vast majority of people (about 90%) of those initially infected with Mycobacterium Tuberculosis do not develop tuberculosis disease.

Without treatment, after 5 years, 50% of patients with pulmonary Tuberculosis will be dead, 25% would be cured and 25% will remain ill with chronic infectious Tuberculosis.


WHO (1996). Tuberculosis/HIV: A Clinical Manual. Geneva: WHO.

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