Heterogeneous mosquito exposure increases <i>Plasmodium vivax</i> and <i>Plasmodium falciparum</i> co-infections: a modelling study

In malaria-endemic regions, <i>Plasmodium vivax</i> and <i>Plasmodium falciparum</i> coexist and may interact. For instance, fevers induced by <i>P. falciparum</i> might activate dormant <i>P. vivax</i> parasites and concurrent radical cure of both species has been proposed to prevent relapses. Heterogeneous mosquito exposure may contribute to the dependence of both parasites. We conducted a literature review on their respective prevalence and that of co-infections. The data revealed a positive correlation between <i>P. vivax</i> and <i>P. falciparum</i> prevalence, and co-infection prevalences exceeding expectations assuming infections occur independently. We used the review data to fit a compartmental model of co-infections that features heterogenous mosquito exposure. The fit suggests that heterogeneous exposure sufficiently explains the observed departure from independence. Finally, we performed simulations under the model assessing the impact on <i>P. vivax</i> prevalence of the activation-by-fever hypothesis and the radical cure proposition. We demonstrated a moderate impact of allowing <i>P. falciparum</i> fevers to reactivate <i>P. vivax</i> and a substantial impact of treating <i>P. falciparum</i> cases with radical cure. Our model highlights dependence between <i>P. falciparum</i> and <i>P. vivax</i> and emphasizes the influence of heterogeneous mosquito exposure. This simple framework can inform the design of more complex models assessing integrated malaria control strategies in coendemic regions.