Tuberculosis (commonly shortened to TB) is an infection cused by
thr bacterium mycobacterium tuberculosis , which most commonly affects
the lungs (pulmonary TB) but can also affect the central nervous
system(meningitis) , lymphatic system , circulatory system , genitourinary
system , bones and joints.
Tuberculosis is one of the most deadly and common major infectious
diseases today , infecting two billion people or one third of the
world's population . nine million new cases of disease,resulting
in two million deaths occur annually,mostly in the developing countries.
The diagnosis of tuberculosis is largely based on conventional
approachs, which rely on clinical features,results of microscopy
and culture.clinical features are not generally diagnostic and microscopy,while
rapid,lacks sensitivity and specificity.culture methods are time
consuming .(2 -3 weeks to obtain the results) .
An important technical advance is TB diagnosis has been the development
of nucleic acid amplification(NAA) assays which will allow direct
direction of tubercle bacilli as well as other mycobacteria.PCR
is most commonly used for this purpose.