Metagenomic analysis reveals extreme complexity of Plasmodium spp. infections in high transmission in West Africa.

Mixed-species, mixed-strain Plasmodia infections are known to occur in humans in malaria endemic areas. To date, the true extent of this complexity has not been explored in high-burden countries of sub-Saharan Africa. Here we take a metagenomic lens to infections obtained by sampling variable blood volumes from residents living in high, seasonal transmission in northern Ghana. We identified significantly higher prevalence of Plasmodium spp. and inter-/intra-species complexity in larger blood volumes. Overall, malaria infections displayed high levels of metagenomic complexity comprising single-, double-, and triple-species infections with varying levels of complexity for P. falciparum, P. malariae, P. ovale curtisi, and P. ovale wallikeri. We present evidence of individuals with greater susceptibility to highly-complex infections that cannot be explained by age or location. The implications of these findings to malaria epidemiology and control are illustrated by a geographic scaling exercise to district and region levels in Ghana.