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Table 1 Tuberculin skin test (TST) & Cytokines production in whole blood cultures [ESAT-6/CFP-10 & PPD] in the study population at screening

From: Prevalence of latent tuberculosis infection in Sudan: a case–control study comparing interferon-γ release assay and tuberculin skin test

Variables

House-Hold contacts

Community controls**

p value

 

(n = 98) ¤

(n = 186)

 

  TST (mean ± SD)

5 ±6

2 ±3

0.000*

< 5 mm

59 (60.2%)

139 (83.2%)

0.000*

5 - 9 mm

12 (12.2%)

13 (7.8%)

0.04*

10 - 14 mm

13 (13.2%)§

14 (8.4%)

0.1

≥ 15 mm

14 (14.4%)§

01 (0.6%)

0.000*

IFN-γ Mean level IU/ml:

  Purified Protein Derivative:

Mean ± SD

0.5 ± 0.6

0.3 ± 0.4

0.4

< 0.35

57/98 (58.2%)

130/186 (69.9%)

0.06

0.35-1.0

28/98 (28.6%)

44/186 (23.6%)

0.1

1.1-2.0

13/98 (13.2%)

12/186 (6.5%)

0.3

  ESAT-6 + CFP −10 ± TB7•7:

Mean ± SD

0.5 ± 0.7

0.2 ± 0.2

0.000*

< 0.35

56/98 (57.1%)

136/186(73.2%)

0.03*

0.35 - 1.0

18/98 (18.4%)§

41/186 (22.2%)

0.01*

1.1 - 2.0

24/98 (24.5%)§

09/186 (4.6%)

0.2

  1. Continuous variable are expressed as means ± SD. *Significant difference (p < 0.05).
  2. §There was a low correlation between IFN-γ level >0.35 IU/ml and TST ≥10 mm (r = 0.4).
  3. All volunteers had history of BCG vaccination that was confirmed in the majority (>85%) by presence of a scar. **Nineteen CCs did not report for TST reading.