title: Trends in the annual risk of tuberculous infection in India.
abstract: METHODS
  Twenty-four districts in India.
  
  
  OBJECTIVE
  To evaluate trends in annual risk of tuberculous infection (ARTI) in each of four geographically defined zones in the country.
  
  
  METHODS
  Two rounds of house-based tuberculin surveys were conducted 8-9 years apart among children aged 1-9 years in statistically selected clusters during 2000-2003 and 2009-2010 (Surveys I and II). Altogether, 184,992 children were tested with 1 tuberculin unit (TU) of purified protein derivative (PPD) RT23 with Tween 80 in Survey I and 69,496 children with 2TU dose of PPD in Survey II. The maximum transverse diameter of induration was measured about 72 h after test administration. ARTI was computed from the prevalence of infection estimated using the mirror-image method.
  
  
  RESULTS
  Estimated ARTI rates in different zones varied between 1.1% and 1.9% in Survey I and 0.6% and 1.2% in Survey II. The ARTI declined by respectively 6.1% and 11.7% per year in the north and west zones; no decline was observed in the south and east zones. National level estimates were respectively 1.5% and 1.0%, with a decline of 4.5% per year in the intervening period.
  
  
  CONCLUSIONS
  Although a decline in ARTI was observed in two of the four zones and at national level, the current ARTI of about 1% in three zones suggests that further intensification of TB control activities is required.
authors: Epidemiology and Research Division, National Tuberculosis Institute, Bangalore, India. nti@ntiindia.org.in
authors: V K
authors: VK
authors: Chadha
authors: R
authors: R
authors: Sarin
authors: P
authors: P
authors: Narang
authors: K R
authors: KR
authors: John
authors: K K
authors: KK
authors: Chopra
authors: R
authors: R
authors: Jitendra
authors: D K
authors: DK
authors: Mendiratta
authors: V
authors: V
authors: Vohra
authors: A N
authors: AN
authors: Shashidhara
authors: G
authors: G
authors: Muniraj
authors: P G
authors: PG
authors: Gopi
authors: P
authors: P
authors: Kumar
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use; D001500:BCG Vaccine / Q000008:administration & dosage; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003140:Communicable Disease Control / Q000379:methods; D006306:Health Surveys; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D011237:Predictive Value of Tests; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D012423:Rural Health; D013997:Time Factors; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D014504:Urban Health
chemical_list: D000995:Antitubercular Agents; D001500:BCG Vaccine