Modelling the impact of different intervention packages for malaria control under varying intensities of pyrethroid resistance
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Date
2025-11-19
Journal Title
Journal ISSN
Volume Title
Publisher
Malaria Journal
Abstract
Background Malaria control in sub-Saharan Africa faces significant challenges from biological threats, such as insec-
ticide resistance and adaptive vector behaviours, as well as increasing financial constraints, which necessitate stra-
tegic intervention planning to maximize impact. This study assesses the effectiveness of combining vector control
methods, case management, and immunoprevention to reduce malaria in Tanzania, considering varying intensities
of insecticide resistance in the main vector species.
Methods A compartmental model was developed to simulate malaria transmission, incorporating the dominant
vectors: Anopheles funestus (anthropophilic and endophilic) and Anopheles arabiensis (zoophilic and exophilic). The
model was used to analyse the impacts of insecticide-treated nets (ITNs), indoor residual spraying (IRS), and biolar-
vicides, used singly or in combinations, under varying intensities of pyrethroid resistance. The analysis was further
expanded to explore the impacts of adding case management (treatment using artemisinin-based combinations)
and immunization (RTS,S/AS01 and R21/Matrix-M vaccines).
Results At moderate levels of pyrethroid resistance (50%), achieving at least 71% ITN coverage combined
with either 50% IRS or 32% biolarvicide coverage reduces the effective reproduction number (Re ) to below 1. How-
ever, at high resistance levels (exceeding 75%), the effective reproduction number (Re ) consistently remains above 1,
irrespective of the type or combination of vector control interventions. Adding immunization (≥ 40% coverage)
to ITNs (80% coverage), along with effective treatment (80% coverage), can further reduce the proportion of infec-
tious individuals to <20% and Re below 1, even under high resistance intensities.
Conclusions Compared to ITNs alone, combining ITNs with IRS and/or biolarvicides greatly improves malaria control
at low to moderate intensities of pyrethroid resistance but yields no additional benefits at high resistance intensi-
ties. However, integrating these vector control strategies with immunization and effective case management using
artemisinin-based combination therapy (ACT) further enhances impact by reducing both parasite transmission
and the infectious reservoir
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