Tuberculosis transmission in public locations in Tanzania: A novel approach to studying airborne disease transmission

- Novel approach of studying airborne disease transmission to identify TB transmission hotspots.
- Prisons have the highest annual risk of TB transmission followed by public transport and indoor markets.
- Lower risk of TB transmission was estimated for schools, religious and social halls.
- This approach can guide identification of TB transmission hotspots and targeted control interventions in high burden countries.

SummaryObjectivesFor tuberculosis (TB) transmission to occur, an uninfected individual must inhale the previously infected breath. Our objective was to identify potential TB transmission hotspots in metropolitan city of Dar es Salaam, Tanzania and to model the annual risk of TB transmission in different locations of public importance.MethodsWe collected indoor carbon dioxide (CO2) data from markets, prisons, night clubs, public transportation, religious and social halls, and from schools. Study volunteers recorded social contacts at each of the locations. We then estimated the annual risks of TB transmission using a modified Wells-Riley equation for different locations.ResultsThe annual risks of TB transmission were highest among prison inmates (41.6%) and drivers (20.3%) in public transport. Lower transmission risks were found in central markets (4.8% for traders, but 0.5% for their customers), passengers on public transport (2.4%), public schools (4.0%), nightclubs (1.7%), religious (0.13%), and social halls (0.12%).ConclusionFor the first time in a country representative of sub-Saharan Africa, we modelled the risk of TB transmission in important public locations by using a novel approach of studying airborne transmission. This approach can guide identification of TB transmission hotspots and targeted interventions to reach WHO's ambitious End TB targets.