Estimating the extent, patterns and consequences of heterogeneity in malaria dynamics

Background

The uneven distribution of malaria is apparent on a small scale, within a single study site or even cluster of houses. Transmission varies with mosquito densities related to breeding sites, but sources of heterogeneity in other environmental, behavioural and economic factors have also been implicated. Hotspots, areas of relatively high transmission, have been identified. Heterogeneity has implications for many areas of malaria epidemiology, not least the design of intervention strategies. Whilst the existence of heterogeneity is acknowledged, the extent and patterns of heterogeneity in malariological outcomes and in risk factors have not been well quantified. The degree to which areas of relatively higher and lower transmission are interconnected, and also the degree to which interventions can impact on hotspots, are also crucial determinants of the effectiveness of control strategies.

Objectives

This project seeks to estimate how much heterogeneity there is, and under what circumstances it matters. 1. Develop a statistical model to estimate degree of focality or interconnectedness of transmission using data from repeated community surveys with high-resolution genotyping to distinguish infections 2. Characterize heterogeneity in a number of settings and assess the impact of these patterns using simulation models developed at Swiss TPH 3. Estimate the impact of interventions on heterogeneity and the persistence of hotspots.

Expected output

This project will provide an overview of patterns of heterogeneity and hotspots together with predictions of their impact, a model to estimate the extent to which infections spread to or from hotspots of transmission, and estimates of the impact of interventions on hotspots. Together these outputs provide information on the extent, patterns and consequences of heterogeneity, and inform the design of control strategies and the parameterization of models of malaria dynamics.