Interpretation of repeat tuberculin skin testing in international adoptees: conversions or boosting.
BACKGROUND
Internationally-adopted children are a unique group of Bacille Calmette-Guérin (BCG)-vaccinated children with high rates of latent tuberculosis infection (LTBI) in whom serial tuberculin skin tests (TST) are recommended. No study has measured the incidence of TST conversion in these children.


METHODS
Internationally-adopted children completed baseline and follow-up TST to measure the incidence of Mycobacterium tuberculosis infection and factors associated with TST conversion. Data were collected regarding age, gender, birth country, vaccination history, history of tuberculosis (TB) exposure, previous TB screening, and preadoptive environment. All children completed physical examinations including a standardized evaluation for TB, anthropometric assessment, and documentation of BCG scar.


RESULTS
Fourteen percent of children (N = 390) had evidence of LTBI at baseline. Children were more likely to have LTBI if they were older, BCG vaccinated, or had been in the United States longer. An additional 13% of children had TST indurations > or = 10 mm at follow-up testing. Regardless of BCG vaccination status or nutritional status, children who were younger at baseline were more likely to have a TST induration > or = 10 mm at follow-up.


CONCLUSIONS
International adoptees have significant risk of LTBI. Although our findings suggest that recent infection with M. tuberculosis led to TST conversion in some children, the increase in follow-up TST induration could also be attributed to TST boosting resulting from prior BCG vaccination. When serial TST testing is completed in young, BCG-vaccinated children, interpretation of the follow-up TST should consider baseline TST results.
Mandalakas
Anna M
AM
Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA. anna.mandalakas@case.edu
Kirchner
H Lester
HL
Zhu
Xaiobei
X
Yeo
Kee Thai
KT
Starke
Jeffrey R
JR
D000300:Adoption; D001500:BCG Vaccine / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D054242:Emigrants and Immigrants; D005260:Female; D006801:Humans; D007223:Infant; D038622:Internationality; D008137:Longitudinal Studies; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology; D015596:Nutrition Assessment; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology / Q000517:prevention & control; D014481:United States
D001500:BCG Vaccine