Tuberculosis transmission in Kenya: results of the third National Tuberculin Survey

Abstract

Setting: Kenya, a country with a high burden of tuberculosis (TB) and human immunodeficiency virus (HIV) infection.

Objectives: To assess the prevalence of TB infection, bacille Calmette-Guérin (BCG) coverage and the annual risk of tuberculosis infection (ARTI), and to compare estimates with previous findings.

Methods: A sample of primary school children aged 6-14 years from the same study districts sampled in previous surveys were tuberculin skin tested using the Mantoux method from September 2004 to July 2007. The prevalence of TB infection was estimated by the mirror method, with the mode at 17 mm.

Results: Of the 94 771 registered children, 76 676 (80.9%) completed the survey investigations, 12 107 (15.8%) of whom had no BCG scar. The prevalence of TB infection was estimated at 10.2%, with a corresponding ARTI of 1.1%. The ARTI obtained from the current survey is comparable to that of the 1994-1996 survey and higher than that of the 1986-1990 survey. The BCG coverage was comparable with the 1994-1996 survey and higher than in the 1986-1990 survey.

Conclusion: TB transmission in Kenya has remained the same over the last decade, which suggests that activities undertaken by the TB control programme have been sufficient to hold TB transmission steady, but insufficient to reduce it.