Diagnosing extra-pulmonary TB

TB that affects different parts of the body other than lungs—extra-pulmonary TB—like lymph nodes or bones, accounts for nearly 15 per cent of all TB cases in India. Even though the burden of pulmonary cases is much higher, the other types of TB pose specific challenges related to diagnosis. Jyotsna Singh spoke to Rohit Sarin, director of LRS Institute of TB & Respiratory Diseases in Delhi on dealing with these challenges

 
By Jyotsna Singh
Last Updated: Saturday 04 July 2015

Rohit SarinWhat is the major problem in dealing with extra-pulmonary TB?

Lack of proper diagnostic tools. In pulmonary TB, test of the sputum is enough to determine the infection. The bacteria are easily seen with the eyes. But in extra-pulmonary TB, one cannot see the organism directly in many cases. Here, the infected tissue's histologic structure gets changed in a particular way and only these changes tell us whether a person is infected or not. This also means that there cannot be a 100 per cent definitive diagnosis of the disease. Furthermore, we can never be sure if a person has been fully cured of TB. The shape of the affected tissue often does not come back to original even after the disease is cured. Thus, declaring someone affected or free from TB is presumptive.

What are the challenges in treating these patients?

Pulmonary TB is tested in a microscopy centre which is easy to set up. Thus, the Government of India guidelines suggest one centre for every 100,000 population. But extra-pulmonary diagnosis needs pathology labs which are tough to set up. They are found only in relatively big hospitals. The samples collected from peripheries are sent to these hospitals and one has to wait till the results reach back. This is the main challenge.

This lack of facilities also make it difficult to treat multi-drug resistant cases for which repeated tests would have to be done. Only after substantial treatment is over that the doctor realises the patient is resistant to certain drugs and is not responding.

What is the way out?

The only way out is to find better diagnostic tools. Research in various parts of the world, including India, is going on, but we still have to see how successful they are.

This has impact on data too. If a patient has pulmonary as well as extra-pulmonary TB, then it becomes a part of pulmonary TB by definition as diagnosis for extra-pulmonary TB is not definitive.

 

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