Prevalence of Mantoux test positivity among apparently healthy children in Maiduguri, Nigeria

Abstract

Background: The impact of TB is highest in the developing countries of Asia and Africa especially among children in whom the diagnosis is challenging. Periodic skin testing by Mantoux method is recommended in children residing in high TB prevalence regions. Objective: To determine the prevalence of Mantoux test positivity among BCG-vaccinated and non-vaccinated under-five children in Maiduguri, Nigeria. Method: The study was descriptive and cross-sectional, conducted in Maiduguri, Nigeria, among apparently healthy 3-59 months old children who attended the child welfare clinics of the University of Maiduguri Teaching Hospital and two Primary Health Care centres from May to August 2008. All children who fulfilled the inclusion criteria were evaluated for history of BCG vaccination and Mantoux tested. Results: The study included 390 children, comprising 201 (51.5%) males and 189(48.5%) females; the male to female ratio was 1.1:1. Thirty one out of the 390 (7.9%) children had a positive Mantoux reaction, 27(87 %) of whom had induration of 10-14mm, while the remaining 4 (13 %) had induration of 15-20mm. The prevalence of Mantoux positivity among the vaccinated children was 10.1% and among the non-vaccinated children was1.1%, (p= 0.0034). No significant statistical difference for Mantoux positivity was observed between the sexes, (p= 0.087), and the different age groups, (p= 0.159). Conclusion: Although, positive Mantoux response is usually attributed to TB infection, the effect of previous BCG on Mantoux test reactivity especially in children should be taken into consideration in the interpretation of Mantoux test responses.