Molecular Detection of Airborne Mycobacterium tuberculosis in South African High Schools

South African adolescents carry a high tuberculosis disease burden. It is not known if schools are high-risk settings for (MTB) transmission. To detect airborne MTB genomic DNA in classrooms. We studied 72 classrooms occupied by 2,262 students in two South African schools. High-volume air filtration was performed for median 40 (interquartile range [IQR], 35-54) minutes and assayed by droplet digital PCR (ddPCR)-targeting MTB region of difference 9 (RD9), with concurrent CO concentration measurement. Classroom data were benchmarked against public health clinics. Students who consented to individual tuberculosis screening completed a questionnaire and sputum collection (Xpert MTB/RIF Ultra) if symptom positive. Poisson statistics were used for MTB RD9 copy quantification. ddPCR assays were positive in 13/72 (18.1%) classrooms and 4/39 (10.3%) clinic measurements ( = 0.276). Median ambient CO concentration was 886 (IQR, 747-1223) ppm in classrooms versus 490 (IQR, 405-587) ppm in clinics (