Heterogeneous mosquito exposure increases Plasmodium vivax and Plasmodium falciparum coinfections: a modelling study

In malaria-endemic regions, Plasmodium vivax and Plasmodium falciparum
coexist and may interact. For instance, fevers induced by P. falciparum
might activate dormant P. vivax 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
coinfections. The data revealed a positive correlation between P. vivax
and P. falciparum prevalence and coinfection prevalences exceeding
expectations assuming infections occur independently. We used the review
data to fit a compartmental model of coinfections that features
heterogeneous 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
P. vivax prevalence of the activation-by-fever hypothesis and the radical
cure proposition. We demonstrated a moderate impact of allowing P.
falciparum fevers to reactivate P. vivax and a substantial impact of
treating P. falciparum cases with radical cure. Our model highlights the
dependence between P. falciparum and P. vivax and emphasises the
influence of heterogeneous mosquito exposure. This simple framework can
inform the design of more complex models assessing integrated malaria
control strategies in co-endemic regions.