title: Comparison of enzyme-linked immunospot assay and tuberculin skin test in healthy children exposed to Mycobacterium tuberculosis.
abstract: OBJECTIVE
  To compare the enzyme-linked immunospot (ELISPOT) assay with the tuberculin skin test (TST) in children for the diagnosis of Mycobacterium tuberculosis infection in the Gambia.
  
  
  METHODS
  We divided child contacts of sputum smear-positive tuberculosis cases into 3 age categories (<5, 5-9, and 10-14 years) and assessed agreement between the 2 tests plus their relationship to prior Bacille Calmette-Guerin (BCG) vaccination. We categorized a child's level of M tuberculosis exposure according to where he/she slept relative to a case: the same room, same house, or a different house. The relationship between exposure and test result was assessed by multiple logistic regression.
  
  
  RESULTS
  In child contacts of 287 cases, 225 (32.5%) of 693 were positive by TST and 232 (32.3%) of 718 by ELISPOT. The overall agreement between tests was 83% and the discordance was not significant. Both tests responded to the M tuberculosis exposure gradient in each age category. The percentage of those who were TST positive/ELISPOT negative increased with increasing exposure. At the lowest exposure level, the percentage of ELISPOT-positive children who were TST negative was increased compared with the highest exposure level. Neither test had evidence of false positive results because of BCG.
  
  
  CONCLUSIONS
  In Gambian children, the ELISPOT is slightly less sensitive than the TST in the diagnosis of M tuberculosis infection from recent exposure, and neither test is confounded by prior BCG vaccination. Evidence of reduced TST sensitivity in subjects with the lowest known recent M tuberculosis exposure suggests that, when maximal sensitivity is important, the 2 tests may be best used together.
authors.affiliation: Tuberculosis Division, Mulago Hospital Complex, Kampala, Uganda. phill@mrc.gm
authors.forename: Philip C
authors.initials: PC
authors.lastname: Hill
authors.forename: Roger H
authors.initials: RH
authors.lastname: Brookes
authors.forename: Ifedayo M O
authors.initials: IM
authors.lastname: Adetifa
authors.forename: Annette
authors.initials: A
authors.lastname: Fox
authors.forename: Dolly
authors.initials: D
authors.lastname: Jackson-Sillah
authors.forename: Moses D
authors.initials: MD
authors.lastname: Lugos
authors.forename: Simon A
authors.initials: SA
authors.lastname: Donkor
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Marshall
authors.forename: Stephen R C
authors.initials: SR
authors.lastname: Howie
authors.forename: Tumani
authors.initials: T
authors.lastname: Corrah
authors.forename: David J
authors.initials: DJ
authors.lastname: Jeffries
authors.forename: Richard A
authors.initials: RA
authors.lastname: Adegbola
authors.forename: Keith P W J
authors.initials: KP
authors.lastname: McAdam
mesh_terms: D000293:Adolescent; D000942:Antigens, Bacterial / Q000276:immunology; D001500:BCG Vaccine; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005192:Family Health; D005714:Gambia; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000276:immunology; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000635:transmission
chemical_list: D000942:Antigens, Bacterial; D001500:BCG Vaccine