The tuberculin skin test in school going adolescents in South India: associations of socio-demographic and clinical characteristics with TST positivity and non-response.
BACKGROUND
India has generally used 1 TU purified protein derivative (PPD) as opposed to 2 TU PPD globally, limiting comparisons. It is important to assess latent TB infection in adolescents given that they may be a target group for new post-exposure TB vaccines. The aim of this study is to describe the pattern and associations of tuberculin skin test (TST) responses (0.1 ml 2 TU) in adolescents in South India.


METHODS
6643 school-going adolescents (11 to <18 years) underwent TST. Trained tuberculin reader made the reading visit between 48 and 96 hours after the skin test


RESULTS
Of 6608 available TST results, 9% had 0 mm, and 12% ≥10 mm responses. The proportion of TST positive (≥10 mm) was higher among older children, boys, those with a history of TB contact and reported BCG immunization Those with no TST response (0 mm) included younger participants (<14 years), those whose mothers were illiterate and those with a recent history of weight loss. Those of a higher socio-economic status (houses with brick walls, LPG gas as cooking fuel) and those with a visible BCG scar were less likely to be non-responders.


CONCLUSIONS
Proportion of non-responders was lower than elsewhere in the world. Proportion of TST positivity was higher in those already exposed to TB and in children who had been BCG immunized, with a zero response more likely in younger adolescents and those with recent weight loss.
St. John's Emmaus TB Research Initiatives (SETRI), Palamaner, India. druppadajan13@gmail.com.
Dharma Rao
DR
Uppada
St. John's Research Institute, Bangalore, India. sumithrars@sjri.res.in.
Sumithra
S
Selvam
St. John's Emmaus TB Research Initiatives (SETRI), Palamaner, India. nelsonsjri@gmail.com.
Nelson
N
Jesuraj
Gilead Sciences, Inc., Foster City, CA, USA. sean.bennett@hotmail.com.
Sean
S
Bennett
KNCV Tuberculosis Foundation, The Hague, The Netherlands. suzanne.verver@kncvtbc.org.|Academic Medical Centre Amsterdam, Amsterdam, The Netherlands. suzanne.verver@kncvtbc.org.
Suzanne
S
Verver
Department of Clinical Science, Infection, Faculty of Medicine and Dentistry, University of Bergen, N-5021, Bergen, Norway. Harleen.Grewal@k2.uib.no.|Department of Microbiology, Haukeland University Hospital, Bergen, Norway. Harleen.Grewal@k2.uib.no.
Harleen M S
HM
Grewal
Physiology and Head of Health and Humanities, St. John's Medical College and St. John's Research Institute, Bangalore, India. mariovaz@sjri.res.in.
Mario
M
Vaz
D000293:Adolescent; D001500:BCG Vaccine / Q000008:administration & dosage; D002648:Child; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D012923:Social Class; D013334:Students; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D014611:Vaccination / Q000706:statistics & numerical data; D015431:Weight Loss
D001500:BCG Vaccine