Molecular Detection of Airborne Mycobacterium tuberculosis in South African High Schools.
Erick Wekesa BunyasiKeren MiddelkoopAnastasia KochZeenat HoosenHumphrey MulengaAngelique K K LuabeyaJustin ShenjeSimon C MendelsohnMichele TamerisThomas Jens ScribaDigby Francis WarnerRobin WoodJason R AndrewsMark HatherillPublished in: American journal of respiratory and critical care medicine (2021)
Rationale South African adolescents carry a high tuberculosis disease burden. It is not known if schools are high-risk settings for Mycobacterium tuberculosis (MTB) transmission. Objectives To detect airborne MTB genomic DNA in classrooms. Methods We studied 72 classrooms occupied by 1,836 students in two South African schools. High-volume air filtration was performed for median 40 minutes (interquartile range 35-54) and assayed by droplet digital PCR (ddPCR) targeting MTB Region of Difference 9 (RD9), with concurrent CO2 concentration measurement. Classroom data were benchmarked against public health clinics. Students who consented to individual TB screening completed a questionnaire and sputum collection (Xpert MTB/RIF Ultra) if symptom-positive. Poisson statistics were used for MTB RD9 copy quantification. Measurements and Main Results ddPCR assays were positive in 13/72 (18.1%) classroom and 4/39 (10.3%) clinic measurements (p=0.276). Median ambient CO2 concentration was 886 ppm (IQR 747-1223) in classrooms vs. 490 ppm (IQR 405-587) in clinics (p<0.001). Average airborne concentration of MTB RD9 was 3.61 copies per 180,000 litres in classrooms vs. 1.74 copies per 180,000 litres in clinics (p=0.280). Across all classrooms, the average risk of an occupant inhaling one MTB RD9 copy was estimated as 0.71% during one standard lesson of 35 minutes. Among 1,836/2,262 (81.2%) students who consented to screening, 21/90 symptomatic students produced a sputum sample (36.2%), of which one was Xpert MTB/RIF Ultra positive. Conclusions Airborne MTB genomic DNA was detected frequently in high school classrooms. Instantaneous risk of classroom exposure was similar to the risk in public health clinics.
Keyphrases
- mycobacterium tuberculosis
- pulmonary tuberculosis
- high school
- public health
- particulate matter
- primary care
- young adults
- air pollution
- cross sectional
- clinical trial
- circulating tumor
- high resolution
- dna methylation
- mass spectrometry
- copy number
- drug delivery
- single molecule
- squamous cell carcinoma
- hiv infected
- patient reported
- big data
- circulating tumor cells
- radiation therapy
- locally advanced
- hiv aids
- global health