Emergents International Centers of Excellence for Malaria Research

PROGRAM PROJECT 1 [PP1]: Genomic Epidemiological Mapping (GEM) of non-falciparum malaria (NFM; Pv, Po, and P. malariae [Pm]) to quantify the parasite reservoir, measure transmissibility to mosquitoes and evaluate the insecticide resistance status of mosquitoes with NFM parasite infections. ABSTRACT/SUMMARY

To date, much of the global research and policy focus interest has been centered upon understanding transmission dynamics of P. falciparum malaria (Pf) and P. vivax (Pv), together accounting for the majority of documented human malaria infections and disease severity. However, the true contribution of non-falciparum

malaria (NFM) –P. ovale (Po wallikeri [Pow] and Po curtisi [Poc]) and P. malariae (Pm) – to the global disease burden remains underappreciated. This is largely because accurate diagnosis for both Po and Pm rely on the use of sensitive nested PCR, given the evidence of usually low parasitemias amongst infected individuals. As

such, these infections are missed by “gold standard” light microscopy routinely used in field settings to diagnose malaria, rendering NFM a silent, and thus neglected disease by the global health community. Moreover, it remains unclear as to which primary vectors are responsible for the transmission of mixed and/or mono-NFM

infections. Increasing pressure from insecticides is leading to changes in host seeking (biting) behavior of primary mosquito vectors, and potentially so-called “secondary vectors”, that may also be increasing exposure to NFM.

Failure to detect and quantify this infectious “hidden” reservoir will likely result in a failure to eliminate residual malaria transmission locally. The overarching hypothesis to be explored in PP1 is that Pf mixed infections with NFM are more prevalent than expected, especially in subclinical but parasitemic populations, and are often

missed by non-molecular based diagnostics. Moreover, transmission of these infections to mosquitoes may be affected by primary or secondary vector species and related IR status in Cameroon and Nigeria. The project will seek to rapidly develop and deploy new genomic field-based tools for NFM – molecular inversion probes (MIPs)

for human biological samples and HMADS assays for determining mosquito species and insecticide resistance status – by leveraging an existing bank of saliva, whole blood, DBS, and liquid blood spots, this Émergents ICEMR program project seeks to: Aim PP1.1. Develop, refine, and implement targeted genomic tools and

determine the distribution of clinical and subclinical Pf, Pv, Po, and Pm infections in Cameroon and Nigeria; Aim PP1.2. Determine transmissibility of NFM mixed infections to Anopheles funestus; and Aim PP1.3. Measure and map the prevalence of insecticide resistance, and associated resistance mechanisms of outdoor biting Anopheles vectors. Key outcomes of PP1 will be to provide insight into the

prevalence of NFM infections, Pf population genomics and drug resistance in mixed infections with NFM, and the relationship of insecticide resistance to mosquito host seeking behavior. Translational outcomes include development of targeted genomic tools for understanding parasite evolution, validation of a deployable all-in-one

MOSAIC genomic tool for mosquito species determination and insecticide resistance marker confirmation, and distribution of a high-resolution, Anopheles vector insecticide-resistance maps to strengthen the quality of malaria elimination efforts in Nigeria and Cameroon.