Synergy and timing: a concurrent mass medical campaign predicted to augment indoor residual spraying for malaria
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Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
African Journal of Agricultural Research
Abstract
Control programmes for high burden countries are tasked with charting effective multi-year strategies
for malaria control within significant resource constraints. Synergies between different control tools, in which more
than additive benefit accrues from interventions used together, are of interest because they may be used to obtain
savings or to maximize health impact per expenditure. One commonly used intervention in sub-Saharan Africa is
indoor residual spraying (IRS), typically deployed through a mass campaign. While possible synergies between IRS and
long-lasting insecticide-treated nets (LLINs) have been investigated in multiple transmission settings, coordinated
synergy between IRS and other mass medical distribution campaigns have not attracted much attention. Recently, a
strong timing-dependent synergy between an IRS campaign and a mass drug administration (MDA) was theoretically
quantified. These synergistic benefits likely differ across settings depending on transmission intensity and its overall
seasonal pattern.
Methods: High coverage interventions are modelled in different transmission environments using two methods: a
Ross–Macdonald model variant and openmalaria simulations. The impact of each intervention strategy was measured
through its ability to prevent host infections over time, and the effects were compared to the baseline case of deploying
interventions in isolation.
Results: By modelling IRS and MDA together and varying their deployment times, a strong synergy was found when
the administered interventions overlapped. The added benefit of co-timed interventions was robust to differences in
the models. In the Ross–Macdonald model, the impact compared was roughly double the sequential interventions in
most transmission settings. Openmalaria simulations of this medical control augmentation of an IRS campaign show
an even stronger response with the same timing relationship.
Conclusions: The strong synergies found for these control tools between the complementary interventions demonstrate
a general feature of effective concurrent campaign-style vector and medical interventions. A mass treatment
campaign is normally short-lived, especially in higher transmission settings. When co-timed, the rapid clearing of the
host parasite reservoir via chemotherapy is protected from resurgence by the longer duration of the vector control.
An effective synchronous treatment campaign has the potential to greatly augment the impact of indoor residual
spraying. Mass screening and treatment (MSAT) with highly sensitive rapid diagnostic tests may demonstrate a comparable
trend while mass LLIN campaigns may similarly coordinate with MDA/MSAT.
Description
Keywords
Malaria, Vector control, IRS, MDA, MSAT, Synergy, Spraying, Ross–Macdonald models, Openmalaria simulation
Citation
Wokorach, G., Edema, H., & Echodu, R. (2018). Sweetpotato seed exchange systems and knowledge on sweetpotato viral diseases among local farmers in Acholi Sub Region-Northern Uganda. African Journal of Agricultural Research , https://doi.org/10.1186/s12936-019-2788-9