Sunday, 29 January 2017
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Dear TechNet viewers


Like many chronic diseases, whether communicable or non communicable, Tuberculosis is also an inadequately understood Vaccine Preventable Disease with frequent change in definition and treatment protocol.

In the recent RNTCP quarterly review meeting, substantial gap in the operational knowledge and differences of opinion were found regarding the Tuberculin Skin Test (TST) - a traditional, simple and reasonably reliable test as a diagnostic aid for the detection of infection by Mycobacterium tuberculosis. The results of TST are not confirmatory but reliable and corroborative in making diagnostic decision.

Hence an attempt is made to present the same in the form of Questions and Answers and a one page job-aid for the TST provider as ready reckoner to be displayed at the nursing station for testing and maintaining Multi Dose Vial Policy [MDVP].

Any error in the whole process from referring the patient to the reading and interpretation of the result and decision making can make a difference of "HANG HIM NOT; LET HIM GO or HANG HIM, NOT LET HIM GO".

Hope a few of the viewers will revert with +ve suggestions



6 years ago

Dear Sir

Thanks for your valuable technical support and knowledge sharing. What surprised me is, this is one of the oldest 'test' and probably performed wrongly even in pioneer teaching institutions. Theses doctors on graduating will continue the same highrisk practice.

Corrigendum: The formula for calculating square area of a circle is pir2 = piD.Wheal sizes quoted ≤2mm / ≤5mm and ≤10mmare already the diameter i.e. r2 hence the field area has to be corrected as≤6.28 / ≤15.7 / ≤31.4 square mm area rspectively.


TST team

6 years ago

Dear Moderator,

I completly agree with what Dr. Narayana Holla is saying. We need to have 0.1ml as PPD volume for TST testing. While we give 0.1ml rabies vaccine intradermally the vaccine vial volume does not matter, it can be 1ml or 0.5ml but the dose of ID rabies vaccine is same that is 0.1ml.

The dose has to be the same because it is the streaching effect of this dose on the skin that stimulates the local reaction in the dermis.


Dr. Omesh Kumar harti

Shimla, Himachal Pradesh, India

6 years ago

Playing Football in the Tennis Court

Dear viewers - shring the following for the expert opinion for the benefit of beneficiaries:

Recently I had the opportunity of visiting two Medical Colleges of neighboring state as external examiner. As hobby / passion / spinoff / knowledge sharing / social service, I showed the SOP (Standard Operating Procedure) and the Mantoux (TST) indications / contra indications / when to be careful and how to interpret the results’ job-aid with the faculties of hosting Colleges. On demand I shared the same with them for display in their college for which I am indebted. Other job aids for display at the vaccination site were also shared.

What is surpriZing? In the second college, the preparation used for TST has strength of 10 PPD units in 0.1mL and they are administering 5 units i.e. 0.05mL (volume of 2 units in insulin syringe) which can produce a wheal of < 5 mm diameter on intra-dermal administration i.e. reactogenecity area of < 31.4 square mm. For children they were administering 2 Units, 0.025mL ~ volume of 1unit from the insulin syringe. This produces <2mm wheal i.e. reactogenecity area of <12.56 square mm.

Administration of 5 units in 0.1mL tuberculin on proper ID administration yields ~10 mm wheal i.e. reactogenecity area ≤ 62.8 square mm.

Infection with Mycobacterium develops cell mediated immunity (CMI). On administering purified protein derivative from killed Mycobacteria, reaction sets in, continues and stops at the testing site between 5-6 and 48 to 72 hrs which produces induration and measured in mm for interpreting the result.

What is the doubt / concern? When the field area for “playing / fighting” between the “cells” and the PPD varies from ~12.56 square mm to ~62.8 square will it not have impact on the area of induration?

What I understood is that, irrespective of the strengths of tuberculin unit used, administering 0.1mL quantity is mandatory for measuring / interpreting the reactogenicity, otherwise it will be like playing football in a tennis court.

I feel there is a need for uniform SOP for a country to conduct Mantoux Test (TST).

The same with photos is attached for a little more clarity.

Please do correct me if my ideas are wrong.

6 years ago

Dear viewers

Last month we shared post on Tuberculin Skin Test (TST) / Mantoux test in the form of questions and answers and one page job-aid for display in the Nursing Station where "test" is administered for ambulant patients. This enhanced the capacity of Test provider – the staff nurse who is now demonstrating how to administer Tuberculin intradermally and how to read / measure the induration in mm to the interns and Post Graduates. Interpreting the test result expressed in mm is to be done by the authorized prescriber. On interacting with the post graduates of Department of Medicine, we developed a PPT for presentation for conducting interactive dissemination class in small groups. This resulted in the development of another job-aid – exhibiting Indications / contraindications / when to take precautions & how to interpret the result contextually: the last but one slide.

The same is attached for sharing with the technet viewers for further inputs.

regards from

TST team

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