A 10 mm induration is considered positive in which group?

• A. Healthcare workers
• B. Children under 5
• C. Immigrants and migrant workers
• D. Adults over 65

Answer: (C)

A tuberculin skin test is interpreted using different induration cutoffs based on a person’s risk for TB exposure. A 10 mm induration is considered positive for individuals with a higher risk of TB infection, such as people who have recently immigrated or migrated from countries with high TB prevalence. Their elevated pretest probability means that a 10 mm reaction is enough to indicate latent TB infection.

In contrast, those with lower risk would require a larger induration to be considered positive (for example, a 15 mm cutoff in people with no known risk factors). While some guidelines also use a 10 mm threshold for other high-risk groups, the scenario here specifically points to immigrants and migrant workers as the group for whom a 10 mm reaction is deemed positive.