Malaria elimination campaigns in the Lake Kariba region of Zambia: a spatial dynamical model

TL;DR

This study uses a spatial dynamical model to evaluate malaria elimination strategies in Zambia's Lake Kariba region, highlighting the importance of combined interventions and hotspot targeting for successful elimination.

Contribution

The paper develops and calibrates a village-scale spatial model to simulate intervention impacts, demonstrating effective strategies for malaria elimination in interconnected regions.

Findings

Repeated mass drug administrations are essential.

High net usage enhances elimination success.

Targeting hotspots is as effective as regional campaigns.

Abstract

Background As more regions approach malaria elimination, understanding how different interventions interact to reduce transmission becomes critical. The Lake Kariba area of Southern Province, Zambia, is part of a multi-country elimination effort and presents a particular challenge as it is an interconnected region of variable transmission intensities. Methods In 2012-13, six rounds of mass-screen-and-treat drug campaigns were carried out in the Lake Kariba region. A spatial dynamical model of malaria transmission in the Lake Kariba area, with transmission and climate modeled at the village scale, was calibrated to the 2012-13 prevalence survey data, with case management rates, insecticide-treated net usage, and drug campaign coverage informed by surveillance. The model was used to simulate the effect of various interventions implemented in 2014-22 on reducing regional transmission, achieving elimination by 2022, and maintaining elimination through 2028. Findings The model captured the spatio-temporal trends of decline and rebound in malaria prevalence in 2012-13 at the village scale. Simulations predicted that elimination required repeated mass drug administrations coupled with simultaneous increase in net usage. Drug campaigns targeted only at high-burden areas were as successful as campaigns covering the entire region. Interpretation Elimination in the Lake Kariba region is possible through coordinating mass drug campaigns with high-coverage vector control. Targeting regional hotspots is a viable alternative to global campaigns when human migration within an interconnected area is responsible for maintaining transmission in low-burden areas.