Epidemiological situation of tuberculosis needs to be studied in order to have baseline data and to formulate strategies and to see the impact of such strategies for control of tuberculosis. Various epidemiological indices like tuberculin test, chest X-ray, sputum examination and mortality rate etc. have been used in the past to study the epidemiological situation. However in the given scenario of high prevalence of tuberculosis and large population these methods are found to be expensive and time consuming. Annual risk of infection (ARI) is one epidemiological indices which has been found to be useful to study the epidemiological situation because it is easy to perform and is cost effective. However there is controversy about the study of ARI in BCG vaccinated children. In the era of universal immunization program (UIP) it is very difficult to find sufficient number of non BCG vaccinated children. Therefore ARI was estimated amongst BCG vaccinated and non BCG vaccinated children.
One TU of tuberculin was given to 4053 children. Induration was noted in 3922 at 48 hours with a cut off point of 10mm. The gender, rural/urban and BCG vaccination status was noted.
Prevalence was found to be 7.01%. It was 7.54% in females, 6.74% in males. Prevalence of tuberculin positivity was 7.22% & 6.68% in BCG vaccinated and non BCG vaccinated children respectively. The ARI was 1.12 in all the groups. There was no statistical difference observed between rural/urban, BCG and non BCG vaccinated, male and female subjects.
Study of ARI can be undertaken with ease and there is no difference in BCG vaccinated and non BCG vaccinated children.CLINICAL IMPLICATION: Tuberculin testing to derive ARI can be under taken in both; BCG vaccinated and unvaccinated children to assess the epidemiological situation of a country.
J. Kishan, None.