title: A prospective study of bacillus Calmette-Guérin scar formation and tuberculin skin test reactivity in infants in Lima, Peru.
abstract: OBJECTIVE
  To determine the sensitivity of the bacillus Calmette-Guérin (BCG) scar as an indicator of previous vaccination and to ascertain the tuberculin skin test (TST) response in infancy after vaccination in a community from an area hyperendemic for tuberculosis (TB).
  
  
  METHODS
  In a birth cohort of healthy term infants from Lima, Peru, a single dose of BCG vaccine was administered within the first month of life. Scar formation was assessed biweekly during the first 6 months and again at 3 years after vaccination. TST response was evaluated 6 months after vaccination.
  
  
  RESULTS
  Six months after vaccination, 99% (68) of the newborns exhibited a BCG scar (>2 mm). Scar size did not differ by sex, birth weight, age at vaccination, or nutritional status in the first 2 months. Eighty percent of the participants were found 3 years after vaccination, and all of them had a BCG scar. Mean TST reaction size 6 months after vaccination was 2.9 +/- 0.3 mm. No association was found between sex or age at BCG vaccination and TST size. Only 3 children had a TST >10 mm, and the 3 had a TB contact at home.
  
  
  CONCLUSIONS
  The BCG scar was a sensitive indicator of vaccination status up to 3 years after the administration of the vaccine in the first month of life. Although nearly a quarter of the children had a TST response >5 mm 6 months after vaccination, TST reactions >10 mm did not occur in the absence of exposure to a person with tuberculosis. A cutoff of 10 mm should be used for disease control purposes in people who are born in countries where TB is endemic.
authors.affiliation: Asociación Benéfica Proyectos en Informática, Salud, Medicina y Agricultura, Lima, Peru.
authors.forename: Eunice M
authors.initials: EM
authors.lastname: Santiago
authors.forename: Elise
authors.initials: E
authors.lastname: Lawson
authors.forename: Kari
authors.initials: K
authors.lastname: Gillenwater
authors.forename: Sheela
authors.initials: S
authors.lastname: Kalangi
authors.forename: Andrés G
authors.initials: AG
authors.lastname: Lescano
authors.forename: Gregory
authors.initials: G
authors.lastname: Du Quella
authors.forename: Kristin
authors.initials: K
authors.lastname: Cummings
authors.forename: Lilia
authors.initials: L
authors.lastname: Cabrera
authors.forename: Cecilia
authors.initials: C
authors.lastname: Torres
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
mesh_terms: D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D001500:BCG Vaccine / Q000276:immunology; D002921:Cicatrix / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006130:Growth Disorders / Q000453:epidemiology / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D009748:Nutrition Disorders / Q000453:epidemiology / Q000276:immunology; D010568:Peru / Q000453:epidemiology; D011204:Poverty Areas; D011446:Prospective Studies; D016036:Seroepidemiologic Studies; D014374:Tuberculin Test / Q000706:statistics & numerical data*; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D000907:Antibodies, Bacterial; D001500:BCG Vaccine