From the continent to households, malaria parasite clans, interconnectivity, and survival strategies

From the continent to households, malaria parasite clans, interconnectivity, and survival strategies.

By Dr Alfred AmambuaNgwa

Malaria parasites infected over 220 million individuals in Africa, killing 602000 in 2021 alone. This persistent survival of the main malaria parasite is thanks to its successful arms race with its hosts and deployment of a vast genetic diversity to adapt across variable transmission ecologies and interventions. Understanding the history, genomic variation, population structure and connectivity of malaria parasite across Africa, within regions and down to the households is essential for stratification of interventions and sustaining malaria control and elimination. Coordinating genomic collaboration across 15 African countries, the Plasmodium Diversity Network Africa (PDNA) identified major Western, Central and Eastern African sub-populations, and a highly divergent Ethiopian population. All populations were significantly admixed except for Ethiopia. There is gene flow of indigenous West African drug resistance haplotypes to the East and East African haplotypes from Kenya to West Africa. In West Africa, parasite populations are dwindling from Senegal and The Gambia, risking increased divergence and adaptation to interventions. Drug resistance markers and invasion/antigenic loci are most differentiated between populations, with signatures of balancing selection dominant on surface and host-parasite interaction genes. These genetic signatures are common across country populations, where geneflow and recombination determine the dynamics of clusters of infections that can be targeted for elimination. Infection clusters persist within villages spreading mostly from within households evident from identity-by-descent between parasite isolates. Genomic approaches have defined structure of malaria parasites in Africa, with the basic infection unit being the household, which should be the focus of new intervention approaches such as reactive household chemotherapy.