A model for malaria treatment evaluation in the presence of multiple species

Walker, C.R., Hickson, R.I., Chang, E., Ngor, P., Sovannaroth, S., Simpson, J.A., Price, D.J., McCaw, J.M., Price, R.N., Flegg, J.A., and Devine, A. (2023) A model for malaria treatment evaluation in the presence of multiple species. Epidemics, 44. 100687.

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Abstract

Plasmodium falciparum and P. vivax are the two most common causes of malaria. While the majority of deaths and severe morbidity are due to P. falciparum, P. vivax poses a greater challenge to eliminating malaria outside of Africa due to its ability to form latent liver stage parasites (hypnozoites), which can cause relapsing episodes within an individual patient. In areas where P. falciparum and P. vivax are co-endemic, individuals can carry parasites of both species simultaneously. These mixed infections complicate dynamics in several ways: treatment of mixed infections will simultaneously affect both species, P. falciparum can mask the detection of P. vivax, and it has been hypothesised that clearing P. falciparum may trigger a relapse of dormant P. vivax. When mixed infections are treated for only blood-stage parasites, patients are at risk of relapse infections due to P. vivax hypnozoites. We present a stochastic mathematical model that captures interactions between P. falciparum and P. vivax, and incorporates both standard schizonticidal treatment (which targets blood-stage parasites) and radical cure treatment (which additionally targets liver-stage parasites). We apply this model via a hypothetical simulation study to assess the implications of different treatment coverages of radical cure for mixed and P. vivax infections and a “unified radical cure” treatment strategy where P. falciparum, P. vivax and mixed infections all receive radical cure after screening glucose-6-phosphate dehydrogenase (G6PD) normal. In addition, we investigated the impact of Mass Drug Administration (MDA) of blood-stage treatment. We find that a unified radical cure strategy leads to a substantially lower incidence of malaria cases and deaths overall. MDA with schizonticidal treatment was found to decrease P. falciparum with little effect on P. vivax. We perform a univariate sensitivity analysis to highlight important model parameters.

Item ID: 79189
Item Type: Article (Research - C1)
ISSN: 1878-0067
Keywords: Malaria, Plasmodium falciparum, Plasmodium vivax, Stochastic modelling, Unified treatment
Copyright Information: © 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Funders: National Health and Medical Research Council of Australia (NHMRC), Australian Research Council (ARC)
Projects and Grants: NHMRC 1134989, NHMRC 1196068, ARC DP170103076, ARC DP210101920, ARC DP200100747, ARC FT210100034, NHMRC APP1132975
Date Deposited: 05 Jul 2023 04:02
FoR Codes: 49 MATHEMATICAL SCIENCES > 4901 Applied mathematics > 490102 Biological mathematics @ 50%
42 HEALTH SCIENCES > 4202 Epidemiology > 420205 Epidemiological modelling @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280112 Expanding knowledge in the health sciences @ 80%
28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280118 Expanding knowledge in the mathematical sciences @ 20%
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