Abstract
BackgroundHalting transmission of
Mycobacterium tuberculosis (
Mtb) by identifying infectious individuals early is key to eradicating tuberculosis (TB). Here we evaluate face mask sampling as a tool for stratifying the infection risk of individuals with pulmonary TB (PTB) to their household contacts.
Methods
Forty-six sputum-positive PTB patients in The Gambia (August 2016–November 2017) consented to mask sampling prior to commencing treatment. Incident
Mtb infection was defined in 181 of their 217 household contacts as QuantiFERON conversion or an increase in interferon-γ of ≥1 IU/mL, 6 months after index diagnosis. Multilevel mixed-effects logistical regression analysis with cluster adjustment by household was used to identify predictors of incident infection.
Results
Mtb was detected in 91% of PTB mask samp les with high variation in IS6110 copies (5.3 × 10
2 to 1.2 × 10
7). A high mask
Mtb level (≥20 000 IS6110 copies) was observed in 45% of cases and was independently associated with increased likelihood of incident
Mtb infection in contacts (adjusted odds ratio, 3.20 [95% confidence interval, 1.26–8.12];
P = .01), compared with cases having low-positive/negative mask
Mtb levels. Mask
Mtb level was a better predictor of incident
Mtb infection than sputum bacillary load, chest radiographic characteristics, or sleeping proximity.
Conclusions
Mask sampling offers a sensitive and noninvasive tool to support the stratification of individuals who are most infectious in high-TB-burden settings. Our approach can provide b etter insight into community transmission in complex environments.
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