Van der Zalm MM1, van Soelen N, Mandalakas AM, Jacobsen M, Detjen AK, Marx FM, Grewal H, Cotton MF, Walzl G, Hesseling AC.
Pediatr Infect Dis J. 2016 Feb 29.

Abstract

BACKGROUND: Helminth infestations are associated with T helper cell type 2 (Th2) immune responses, leading to suppression of Th1 responses required to control Mycobacterium tuberculosis (M.tb) infection. We hypothesized that deworming following documented M.tb exposure might improve Th1 immune responses.

METHODS: This was a randomized controlled trial comparing the effect of early versus delayed (after 3 months) deworming on tuberculin skin testing (TST) and Quantiferon-Gold-in-tube (QTF) responses among children from a setting with a known high burden of M.tb and helminth co-infection in Cape Town, South Africa. Children aged 6-15 years with documented M.tb exposure were enrolled. Ascaris lumbricoides status was measured by Ascaris-specific IgE and stool microscopy.

RESULTS: 250 children (mean age 9.6 years) were enrolled; 11.9% (27/227) were Ascaris stool microscopy positive and 54.2% (135/249) were Ascaris stool and / or IgE positive (Ascaris status). In univariable analysis, deworming at enrolment was not associated with a negative TST at 3 months (OR 0.61, 95% CI 0.35- 1.07, p=0.08). In stratified analysis, children with a positive Ascaris status were more likely to be TST negative at 3 months if dewormed early (OR 0.49, 95% CI 0.23-1.04, p=0.06). In multivariable analysis, deworming was not associated with TST status (aOR 0.62, 95% CI 0.34- 1.10, p=0.10). There was no association between deworming and QTF status.

CONCLUSIONS: Deworming in children with recent M.tb exposure is associated with a trend towards a negative TST result. Timing of deworming might influence interpretation of TST in settings with high burdens of TB and helminths.

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