Comparison of tuberculin reaction sizes at 48 and 72 hours among children in Tiruvallur district, south India.

Summary Setting: A rural population in Tiruvallur district, south India. Objective: To study the variability of skin test reaction sizes between 48 and 72 hours. Methods: A tuberculin test survey was conducted among children aged less than 10 years. The reaction sizes were read by the same reader at 48 hours and 72 hours independently. The results of the tuberculin test were compared. Results: Of 957 children aged below 10 years were included in the study; the male and female ratio was 1:1.1. There were no significant differences between the readings of reaction size at 48 and 72 hours. Conclusion: The tuberculin test results can be read either at 48 hours or 72 hours without compromising the validity.