Operational Strategies for the Identification and Targeting of Hotspots of Malaria Transmission

Heterogeneous malaria exposure may result in distinct clusters of higher malaria burden, or hotspots, across space and time. Targeting control programs to these areas may be highly efficient, however, operationally attractive approaches for identifying hotspots are needed for any such program to be sustained by local malaria control programs. The principal aim of this project was to investigate the ability of convenient sampling to identify hotspots of malaria transmission in a low endemic transmission setting in the western Kenyan highlands: 1) The boundaries of hotspots, and associated uncertainties, was determined using a large community survey; 2) The value of convenience sampling to estimate transmission in the community was assessed using cross-­‐sectional surveys of 4964 children in 46 government primary schools and 3042 individuals in five rural-­‐health facilities; 3) The value of compound-­‐level screening of sentinel age groups that are likely to have patent level infections was determined and; 4) The potential use for convenience sampling in hotspot targeted approaches was assessed using spatial information on residences collected during the school and health-­‐facility surveys. The community-­‐based approach was able to detect 77% of the parasite infections in selected hotspots of malaria exposure using field-­‐based tools in sentinel age groups. Both convenience-­‐sampling approaches tested produced similar estimates of malaria transmission to the community when restricted to those residing in the same catchment areas and those testing positive for malaria were more likely to reside in a hotspot. The findings suggest that operationally attractive approaches provide reliable information on malaria transmission and may play an important role in targeted malaria control strategies. Future research on ascertaining what coverage of the hotspot is needed to see sustainable reductions in transmission would provide a threshold with which to gauge the utility of this strategy.