Identifying malaria elimination strategies in the presence of human movement in Bangladesh

TL;DR

Malaria elimination in Bangladesh needs to consider human movement, as targeting only high-case areas isn't enough.

Contribution

A metapopulation model combining human mobility and malaria data to guide targeted elimination strategies.

Findings

Transmission intensity varies greatly across regions with similar case numbers.

Vector control in highly connected, high-transmission areas reduces overall incidence most effectively.

Focusing only on high-incidence areas is insufficient for elimination.

Abstract

Malaria transmission in the Chittagong Hill Tracts (CHT) districts in Bangladesh is characterized by considerable heterogeneity in incidence and the frequent mixing and importation of parasites across districts. Thus, elimination efforts must account for human mobility between endemic and non-endemic locations, and the relative importance of local transmission and parasite importation domestically.

We construct a metapopulation malaria model, parameterized by human mobility data and fit to epidemiological data, to guide elimination efforts in the region.

We find substantial heterogeneity in the transmission intensity across the CHT, with the estimated basic reproduction number varying greatly across places with similar levels of observed incidence. When vector control interventions are applied locally, the greatest impact in reducing overall incidence are in places with both high transmission intensity and high connectivity with more populated districts in the western part of the CHT.

Local elimination in several areas with low or intermediate incidence has a moderate impact in reducing overall incidence, indicating that only focusing on high incidence areas is not sufficient for malaria elimination. More generally, our modeling framework can be used to prioritize resource allocation and identify the conditions necessary for malaria elimination in the region.

Malaria can be hard to eliminate because people move between regions. This movement can carry parasites from areas with high transmission (“source” regions) into areas with lower transmission (“sink” regions). We built a mathematical model of malaria in Bangladesh that combines human movement patterns with disease data. We found that elimination works best when control efforts target areas that have both high malaria transmission and strong connections to larger, more populated districts. Focusing only on areas with high numbers of cases is not enough to achieve elimination. Our model can facilitate public health decisions on where to focus resources and what conditions are needed to achieve malaria elimination in Bangladesh.

Mahmud, Chang et al., model malaria transmission encompassing human mobility and epidemiological data in Bangladesh to guide elimination efforts. Local vector control efforts have the greatest impact when targeted to places with both high transmission intensity and high connectivity.

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