A prospective study of bacillus Calmette-Guérin scar formation and tuberculin skin test reactivity in infants in Lima, Peru.
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.
Santiago
Eunice M
EM
Asociación Benéfica Proyectos en Informática, Salud, Medicina y Agricultura, Lima, Peru.
Lawson
Elise
E
Gillenwater
Kari
K
Kalangi
Sheela
S
Lescano
Andrés G
AG
Du Quella
Gregory
G
Cummings
Kristin
K
Cabrera
Lilia
L
Torres
Cecilia
C
Gilman
Robert H
RH
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*
D000907:Antibodies, Bacterial; D001500:BCG Vaccine