Background: The epidemiology of pediatric tuberculosis (TB) from 1995 to 2000 in Harris County, TX, has been previously reported. This study was conducted to evaluate the continued trends of Mycobacterium tuberculosis clustering and the role of genotyping in pediatric TB.
Methods: Data came from the Houston Tuberculosis Initiative, a prospective population-based active surveillance and molecular epidemiology project. The study population consisted of TB patients ≤18 years of age diagnosed in Harris County, TX, from 2000 to 2004. Available Mycobacterium tuberculosis isolates were characterized by insertion sequence 6110 restriction fragment length polymorphism and spoligotyping.
Results: One hundred three pediatric TB cases were enrolled in the Houston Tuberculosis Initiative study from 2000 to 2004. Sixty-one (59%) patients had potential source cases. Mycobacterium tuberculosis isolates were available and genotyped for 36 pediatric cases; 27 (75%) were clustered into 22 different genotypes. Of the 20 genotyped patients with a potential source case, 16 (80%) were clustered. Genotypes matched the potential source case in 12 cases. Eleven of the 16 (69%) genotyped patients without a potential source case were clustered.
Conclusions: Compared with pediatric cases between 1995 and 2000, there was a significant increase in the number of patients with unknown potential source cases that were clustered within the Houston Tuberculosis Initiative database. Because genotypic clustering is associated with recent transmission, there appears to be a failure in the identification of potential source cases through contact tracing. Reduced funding of public health departments forces more limited TB control activities and therefore could pose a threat to TB control.