Objective: Tuberculosis (TB) is an important infectious disease
worldwide. Tuberculin skin test (TST) is the standard test for
diagnosis of tuberculosis infection; Bacillus Calmette-Guerin (BCG)
vaccination at birth has effects on this test. The aim of this study
was to determine the prevalence of positive TST cases among 7- to
11-year-old primary school children and also to follow test-positive
individuals for a five-year period. Methods: TST was performed on
10.184 children aged 7-11 years sampled by cluster random method in
Kermanshah, West Iran. Those who had a positive test result (i.e. an
induration of =15 mm following 72 hours of injecting 0.1 ml of 5
tuberculin units of purified protein derivative from Mycobacterium
tuberculosis) were followed for five years to determine the presence of
active TB. Also tuberculin positive rates at cut-off points of 10 mm
and =15 mm for boys and girls and at different ages were derived and
compared using the chi-squared test. Findings: Of 10.184 studied
subjects, 830 (8.15%) cases showed positive TST. This rate was 8.7% in
boys and 7.8% in girls (P=0.1). A significant linear trend was found
between the tuberculin positive rates and age at all cut-off points
(P<0.001). No active TB was detected during 5-year follow-up.
Conclusion: The rate of positive TST cases in primary school children
in Kermanshah, Iran was 8.15% with no new cases of active tuberculosis
detection within five-year follow-up
