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Surprisingly high specificity of the PPD skin test for M. tuberculosis infection from recent exposure in The Gambia.
- Source :
-
PloS one [PLoS One] 2006 Dec 20; Vol. 1, pp. e68. Date of Electronic Publication: 2006 Dec 20. - Publication Year :
- 2006
-
Abstract
- Background: Options for intervention against Mycobacterium tuberculosis infection are limited by the diagnostic tools available. The Purified Protein Derivative (PPD) skin test is thought to be non-specific, especially in tropical settings. We compared the PPD skin test with an ELISPOT test in The Gambia.<br />Methodology/principal Findings: Household contacts over six months of age of sputum smear positive TB cases and community controls were recruited. They underwent a PPD skin test and an ELISPOT test for the T cell response to PPD and ESAT-6/CFP10 antigens. Responsiveness to M. tuberculosis exposure was analysed according to sleeping proximity to an index case using logistic regression. 615 household contacts and 105 community controls were recruited. All three tests assessed increased significantly in positivity with increasing M. tuberculosis exposure, the PPD skin test most dramatically (OR 15.7; 95% CI 6.6-35.3). While the PPD skin test positivity continued to trend downwards in the community with increasing distance from a known case (61.9% to 14.3%), the PPD and ESAT-6/CFP-10 ELISPOT positivity did not. The PPD skin test was more in agreement with ESAT-6/CFP-10 ELISPOT (75%, p = 0.01) than the PPD ELISPOT (53%, p<0.0001). With increasing M. tuberculosis exposure, the proportion of ESAT-6/CFP-10 positive contacts who were PPD skin test positive increased (p<0.0001), and the proportion of ESAT-6/CFP-10 negative contacts that were PPD skin test negative decreased (p<0.0001); the converse did not occur.<br />Conclusions/significance: The PPD skin test has surprisingly high specificity for M. tuberculosis infection from recent exposure in The Gambia. In this setting, anti-tuberculous prophylaxis in PPD skin test positive individuals should be revisited.
- Subjects :
- Adolescent
Adult
Aged
Antigens, Bacterial immunology
Bacterial Proteins immunology
Case-Control Studies
Child
Child, Preschool
Contact Tracing statistics & numerical data
Enzyme-Linked Immunosorbent Assay methods
Enzyme-Linked Immunosorbent Assay statistics & numerical data
Female
Gambia epidemiology
Housing
Humans
Infant
Male
Middle Aged
Sensitivity and Specificity
T-Lymphocytes immunology
Tuberculosis, Pulmonary epidemiology
Tuberculosis, Pulmonary prevention & control
Tuberculosis, Pulmonary transmission
Contact Tracing methods
Tuberculin Test statistics & numerical data
Tuberculosis, Pulmonary diagnosis
Subjects
Details
- Language :
- English
- ISSN :
- 1932-6203
- Volume :
- 1
- Database :
- MEDLINE
- Journal :
- PloS one
- Publication Type :
- Academic Journal
- Accession number :
- 17183699
- Full Text :
- https://doi.org/10.1371/journal.pone.0000068