High Discordance Between Pre-US and Post-US Entry Tuberculosis Test Results Among Immigrant Children: Is it Time to Adopt Interferon Gamma Release Assay for Preentry Tuberculosis Screening?

BACKGROUND: Since 2007, immigration applicants 2-14 years old with a tuberculin skin test (TST) ≥10 mm and an otherwise negative evaluation for tuberculosis (TB) are assigned a classification for TB infection and instructed to seek domestic evaluation upon arrival in the US in accordance with Centers for Disease Control and Prevention instructions. We examined the characteristics and outcome of domestic evaluation of immigrant children who arrived in California with a positive TST on preimmigration examination to inform the preimmigration TB screening process.

METHODS: Retrospective analysis of the characteristics and results of domestic evaluation of immigrants 2-14 years old who arrived in California with a classification for TB infection during October 1, 2008-September 30, 2013 was performed. TB disease was determined by matching preimmigration records with the California TB registry.

RESULTS: Among a total of 12,544 immigrant children included, 7786 (62%) were evaluated for TB postentry. Of these, 5243 (67%) were tested with TST or interferon gamma release assay (IGRA), and 2371 (45%) had a positive test. Of those tested with IGRA (n = 4035), 914 (23%) were positive. The proportion with positive IGRA increased significantly with age (years): 2-4 (11%), 5-9 (19%), 10-14 (28%), P < 0.0001; was lowest among arrivers from China (6%) and highest among arrivers from Mexico (48%). Nine children (0.07%) had TB disease within 5 years after arrival.

CONCLUSIONS: The majority of immigrant children with a positive preimmigration TST tested negative for TB infection on domestic evaluation using TST or IGRA. Inclusion of IGRA in preimmigration TB screening is likely to reduce subsequent testing, treatment and cost of evaluations among immigrant children to the US.