The impact of hotspot-targeted interventions on malaria transmission: study protocol for a cluster-randomized controlled trial

Abstract

BackgroundMalaria transmission is highly heterogeneous in most settings, resulting in the formation of recognizable malaria hotspots. Targeting these hotspots might represent a highly efficacious way of controlling or eliminating malaria if the hotspots fuel malaria transmission to the wider community.Methods/designHotspots of malaria will be determined based on spatial patterns in age-adjusted prevalence and density of antibodies against malaria antigens apical membrane antigen-1 and merozoite surface protein-1. The community effect of interventions targeted at these hotspots will be determined. The intervention will comprise larviciding, focal screening and treatment of the human population, distribution of long-lasting insecticide-treated nets and indoor residual spraying. The impact of the intervention will be determined inside and up to 500 m outside the targeted hotspots by PCR-based parasite prevalence in cross-sectional surveys, malaria morbidity by passive case detection in selected facilities and entomological monitoring of larval and adult Anopheles populations.DiscussionThis study aims to provide direct evidence for a community effect of hotspot-targeted interventions. The trial is powered to detect large effects on malaria transmission in the context of ongoing malaria interventions. Follow-up studies will be needed to determine the effect of individual components of the interventions and the cost-effectiveness of a hotspot-targeted approach, where savings made by reducing the number of compounds that need to receive interventions should outweigh the costs of hotspot-detection.Trial registrationNCT01575613. The protocol was registered online on 20 March 2012; the first community was randomized on 26 March 2012.

High Levels of Asymptomatic and Subpatent Plasmodium falciparum Parasite Carriage at Health Facilities in an Area of Heterogeneous Malaria Transmission Intensity in the Kenyan Highlands

“…The population is predominantly people from the Luo ethnic group, with subsistence farming being the main occupation. 18 Malaria in the area is spatially heterogeneous, with prevalence estimates in primary schools ranging between 0% and 71%, and transmission follows a bimodal seasonal pattern associated with the long and short rainy seasons typically occurring between April and June and between October and December, respectively. 19,20 The predominant malaria vectors in the area are Anopheles funestus and An.…”

“…The surveys were conducted in October of 2011 and July of 2012 to correspond with periods of low and high transmission, respectively, and we examine the sensitivity of these surveys to changes in transmission intensity. 18 Consenting and sample collection. All consenting patients and those accompanying them who attended the outpatient department during the 4-week survey period were eligible for inclusion.…”

“…Filter papers were dried and stored with desiccant at −80 C. In the first year of the survey, axillary temperature was measured using a digital thermometer, and those with temperature 37.2 C were considered febrile. 18 In the second year, tympanic thermometers were used because of the increased accuracy and shorter time to result. For those tested with the tympanic thermometers, only those with temperatures 37.5 C were considered febrile.…”

“…To assess the ability of health facility surveys to provide reasonable estimates of the community, data from a large community cross-sectional survey conducted in July of 2011 in the same study area were used. 18 Data were restricted to those sampled as part of the community survey who resided within the health facility catchment areas as defined by cost-distance analysis, and SCR was calculated as described above. 31 The health facility samples were restricted to those collected in July of 2012 to minimize any potential seasonal bias.…”

What will move malaria control to elimination in South Africa?

“…Interventions targeting hotspots rather than foci of transmission can potentially reduce community wide malaria transmission, [19] particularly if malaria occasionally spills over from hotspots into the surrounding regions. [20] Identification of hotspots through the measurement of increased exposure to malaria vectors or through annual clinical malaria incidence is inefficient at low transmission intensities. The detection of malaria gametocytes or malaria-specific immune responses in human populations has been shown to be more effective at low transmission intensities.…”