Wonder drugs and where to use them: a forecast of ivermectin's impact on malaria in Africa

Abstract

A study in Burkina Faso revealed ivermectin inhibits malaria transmission by killing malaria parasites and mosquitoes. However, it is unknown what effect this drug will have on the malaria transmission intensities of the rest of sub-Saharan Africa (SSA). To address this issue, we created a mathematical model using malaria transmission data from 41 SSA countries to evaluate the antimalarial benefits of a mass drug administration (MDA) of ivermectin. To account for ivermectin's effect on malaria, we incorporate estimates of its ability to inhibit malaria transmission and kill mosquitoes. We consider scenarios where 0, 12.5 %, 25.0 %, and 50.0 % of the population receive ivermectin over five years and estimate malaria incidence averted, disability-adjusted life years saved, and the incremental cost-effectiveness ratio. Our findings show that an MDA of ivermectin to 12.5 %, 25 %, or 50 % of the population annually averts 248.7, 261.4, and 288.7 incidences per thousand people and saves 5.4, 5.7, and 6.3 disability-adjusted life years, respectively. These values indicate that an MDA of ivermectin would be cost-effective in 41, 18, and 6 countries, and very cost-effective in 22, 6, and 3 countries for the 12.5 %, 25 %, and 50 % scenarios. Altogether, our results indicate that ivermectin would prevent a substantial number of malaria incidences and save disability-adjusted life years in the majority of SSA. Therefore, an MDA of ivermectin would greatly aid in ongoing malaria control efforts and should be considered strongly as a complementary intervention to current malaria protocols.

Keywords: Disability-adjusted life-years; Ivermectin; Malaria; Mass drug administration; Mathematical model; Plasmodium falciparum.

Fig. 1

Compartmental diagrams detailing dynamic model of malaria transmission structure. The human compartments ($S,A,T,D,U\text{,}$ and $P$), and mosquito compartments ($M_s$ and $M_i$). Note, for ease of presentation, the dependence of rates on compartments was excluded, along with demographic rates for the mosquito population. For a more detailed compartmental diagram see Fig. S3.

Fig. 2

Incidence averted, and DALYs saved. a) Annual incidence averted per 1000 people by an MDA of ivermectin to 12.5 % (blue), 25 % (red), and 50 % (yellow) of the population, and b) Annual DALYS saved per 1000 people by an MDA of ivermectin to 12.5 % (blue), 25 % (red) and 50 % (yellow) of the population.

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