Abstract:
A recent discovery highlighted that mosquitoes infected with Microsporidia MB are unable
to transmit the Plasmodium to humans. Microsporidia MB is a symbiont transmitted vertically
and horizontally in the mosquito population, and these transmission routes are known to favor the
persistence of the parasite in the mosquito population. Despite the dual transmission, data from field
experiments reveal a low prevalence of MB-infected mosquitoes in nature. This study proposes a
compartmental model to understand the prevalence of MB-infected mosquitoes. The dynamic of the
model is obtained through the computation of the basic reproduction number and the analysis of the
stability of the MB-free and coexistence equilibria. The model shows that, in spite of the high vertical
transmission efficiency of Microsporidia MB, there can still be a low prevalence of MB-infected
mosquitoes. Numerical analysis of the model shows that male-to-female horizontal transmission contributes
more than female-to-male horizontal transmission to the spread of MB-infected mosquitoes.
Moreover, the female-to-male horizontal transmission contributes to the spread of the symbiont only if
there are multiple mating occurrences for male mosquitoes. Furthermore, when fixing the efficiencies
of vertical transmission, the parameters having the greater influence on the ratio of MB-positive to wild
mosquitoes are identified. In addition, by assuming a similar impact of the temperature on wild and
MB-infected mosquitoes, our model shows the seasonal fluctuation of MB-infected mosquitoes. This
study serves as a reference for further studies, on the release strategies of MB-infected mosquitoes, to
avoid overestimating the MB-infection spread.
