Trends in Parasitology
Volume 35, Issue 10, October 2019, Pages 822-834
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Review
Malaria Hotspots: Is There Epidemiological Evidence for Fine-Scale Spatial Targeting of Interventions?

https://doi.org/10.1016/j.pt.2019.07.013Get rights and content
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Highlights

  • Hotspots are an intrinsic part of malaria transmission biology.

  • The size of hotspots depends on the spatial resolution of the input data with important implications for any resulting inference.

  • Where an infectious mosquito/human interacts with a susceptible human/mosquito determines the unit of transmission. The underlying transmission unit is currently unclear and may involve complex nested spatial scales.

  • Infections are more likely to be related when detected closely in space and time; advances in parasite genetic analysis are needed to allow the elucidation of transmission networks at local spatial scales and inform the optimum scale at which interventions need to be undertaken.

  • Evidence for impact on transmission as a result of hotspot-targeted strategies has been limited but is likely due to confounding factors and an incomplete understanding of spatial transmission dynamics.

As data at progressively granular spatial scales become available, the temptation is to target interventions to areas with higher malaria transmission – so-called hotspots – with the aim of reducing transmission in the wider community. This paper reviews literature to determine if hotspots are an intrinsic feature of malaria epidemiology and whether current evidence supports hotspot-targeted interventions. Hotspots are a consistent feature of malaria transmission at all endemicities. The smallest spatial unit capable of supporting transmission is the household, where peri-domestic transmission occurs. Whilst the value of focusing interventions to high-burden areas is evident, there is currently limited evidence that local-scale hotspots fuel transmission. As boundaries are often uncertain, there is no conclusive evidence that hotspot-targeted interventions accelerate malaria elimination.

Keywords

hotspots
transmission dynamics
spatial clustering
unit of transmission

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