Prevalence of Mantoux test positivity among apparently healthy children in Maiduguri, Nigeria
AbstractBackground. The impact of tuberculosis (TB) is highest in the developing countries of Asia and Africa, especially among children, in whom the diagnosis is challenging. Periodic skin testing by the Mantoux method is recommended in children living in regions of high TB prevalence.
Objective. To determine the prevalence of Mantoux test positivity among bacille Calmette-Guérin (BCG)-vaccinated and nonvaccinated
children aged under 5 in Maiduguri, Nigeria.
Method. The study was descriptive and cross-sectional, conducted in 500 apparently healthy children aged 3 - 59 months and attending the child welfare clinics of the University of Maiduguri Teaching Hospital and two primary health care centres in Maiduguri, Nigeria, from May to August 2008. All children who fulfilled the inclusion criteria were evaluated for a history of BCG vaccination and Mantoux tested.
Results. It was possible to perform a Mantoux reading in 78.0% (390/500) of the children. Of these 201 (51.5%) were males
and 189 (48.5%) females (male/female ratio 1.1:1). Thirty-one of the 390 children (7.9%) had a positive Mantoux reaction, 27 (87.1%) with an induration of 10 - 14 mm and the remaining 4 (12.9%) with an induration of 15 - 20 mm. The prevalence of Mantoux positivity was higher among vaccinated than non-vaccinated children (10.1% v. 1.1%, p=0.0034). Differences were also observed between the sexes (p=0.087) and between different age groups (p=0.159), but these were not significant.
Conclusion. Although a positive Mantoux response is usually attributed to TB infection, the effect of previous BCG vaccination on Mantoux test reactivity, especially in children, should be taken into consideration when interpreting Mantoux test responses.