Peter D O Davies

There are two worlds when it comes to the diagnosis of tuberculosis (TB). One world has only smear microscopy at its disposal. There may also be some radiological facilities, usually at the patients' expense. The other world has all modern techniques available, including culture, nucleic acid amplification, molecular diagnostics and sophisticated radiological techniques such as computed tomography and positron emission tomography scanning. The ability to diagnose or misdiagnose TB will vary across these two worlds. In this review, we provide an overview of clinical, radiological, molecular and immunological diagnosis of TB and highlight the common difficulties and pitfalls in TB diagnosis.

The risk of developing tuberculosis is dependent on both the risk of being infected and the risk of infection leading on to active disease. The former will depend on the incidence of tuberculosis in the community where the individual lives or works. The latter will depend on many factors impinging on the individual both genetic and environmental. The greatest single risk factor for developing tuberculosis from infection is concurrent HIV infection. Where these two infections are prevalent tuberculosis case rates have risen dramatically and will continue to do so unless either infection can be curtailed.

Footnotes Conflict of interest None declared.