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Prevention and Control

Is there any role for preventive therapy under RNTCP?

Risk of breakdown from infection to disease is maximum during the period immediately following infection especially among young children. So, asymptomatic child contacts less than 6 years old are routinely recommended chemoprophylaxis.

In RNTCP, asymptomatic child contacts of smear +ve cases and <6 years of age are given preventive treatment without eliciting the infection status by a tuberculin test. On the other hand a very low cut off point of 6mm is chosen for continuation of preventive chemotherapy beyond 3 months? What it the rationale?

Tuberculin test may be negative in the window period. Since the risk of breakdown is maximum during the period immediately following infection especially among young children, asymptomatic child contacts are recommended chemoprophylaxis irrespective of the tuberculin test result. INH given for 3 months reduces the tuberculin size considerably, so a low cut off is used for further continuation.

How do you foresee the role of RNTCP in preventing MDRTB?

The only effective means of preventing MDRTB is to prevent emergence of such cases by DOTS. The proportion of cases with MDR has been demonstrated to come down with implementation of DOTS, in a number of places all over the world viz. Texas, New York, Peru. In Botswana where DOTS is being implemented, the proportion of MDRTB is one twentieth of that in other African countries where DOTS is not being implemented. At RNTCP sites in India, the proportion of patients put on cat II has been seen to reduce gradually. Experience shows if we make sure that patients receive every dose of drugs, the emergence of MDR TB can be prevented.

What is the role of BCG in TB control?

BCG prevents childhood form of TB like disseminated and miliary TB, but has no role in preventing TB in adults especially cavitary forms.

How can we evaluate the impact of RNTCP?

Because of high cure rates, the proportion of re-treatment cases should decrease. There should be decline in prevalence of initial drug resistance. In the community, the impact of any change in disease situation is first reflected in a change in annual risk of infection (ARI) rates. Therefore, repeated ARI surveys along with age distribution of cases can be relied upon for assessment of disease trends in the community. The decline in prevalence of disease occurs next and decline in disease incidence takes much longer.