Tuberculosis is a disease of great antiquity afflicting mankind from very early times and is by far the most frequently encountered  mycobacterial disease. Every year about 8 million people develop Tuberculosis worldwide. India accounts for nearly one third of global burden of tuberculosis. Every year approximately 2.2 million people develop tuberculosis and about 5  lakhs of people die of tuberculosis every year. An increase in HIV prevalence represents a serious threat to TB control in India and changing the epidemiological trends of the disease very fast. The World Health Organization (WHO) declared Tuberculosis as a Global  Health Emergency in 1993.

Chest X-ray view in pulmonary Tb

Mycobacterium  tuberculosis,  the most important causative agent of tuberculosis is a slightly curved or rod shaped bacilli and are non-motile, non  sporing, weakly gram positive, aerobic and  microaerophillic.

The aerosol transmission through droplet nuclei is the usual mode of transmission from cases to contacts. The bacilli engulfed by alveolar macrophages form the primary complex. Gradually as the host immune response degrades the disease spread to various other organs causing extrapulmonary tuberculosis (EPTB).

The clinical manifestations of  EPTB are not clear-cut and clinicians depend on various diagnostic methods, some of which like CT Scan, MRI, which are expensive and are not practical particularly in developing countries. The DNA probe, PCR techniques are not only costly but needs skilled technician with great dedications for  their work.

SEVA TB ELISA (IgG & Ag) system for detection of antibodies and antigen in tuberculosis has been developed in this institute. The detection of  IgG antibody (titre 1:600 and above) by Indirect  Penicillinase  ELISA against M.tb. ES 31/41 antigen in pulmonary and extra pulmonary tuberculosis are suggestive of active tuberculosis infection. Antigen is detected using affinity-purified antibody by Sandwich ELISA. A serum with an antigen titre of 1:300 and above is considered as positive reaction. The test is quite helpful in childhood tuberculosis where it is difficult to obtain sputum for AFB examination. Mantoux test is  also not very sensitive due to cross-reaction with BCG vaccination.  This test has been found to be useful in clinically suspected and ATT responded tuberculosis cases which were negative for AFB smear and culture examination. This test is also useful in confirming tubercular aetiology in extra pulmonary tuberculosis (bone & joint Tb, abdominal Tb, Meningitis, Tubercular lymphadenitis, Genitourinary Tb etc.).