Genomic insights into host shifts between Plasmodium vivax and Plasmodium simium in Latin America

Malaria in Latin America is largely caused by Plasmodium vivax , but its lesser-known sister species, Plasmodium simium , has recently emerged from monkeys to infect humans, thus raising new public health concerns. By analyzing 719 monkey samples and whole genome variations for 19 P. simium and 408 P. vivax isolates, we investigated the evolutionary history and population genetics of the two species. P. vivax , typically restricted to humans, was identified in three Colombian and one Brazilian monkeys, suggesting host niche expansion. Genetic analysis reveals recent genetic exchanges between both species and indicates that P. simium originated from a host jump approximately a century ago, possibly linked to P. vivax migration from Mexico to Brazil. Genome-wide scans revealed signals of positive selection in P. simium genes involved in interactions with primate hosts and mosquito vectors. These findings highlight P. simium evolutionary history and zoonotic malaria risks, and underscore the need to include monkeys in malaria prevention measures while ensuring human-wildlife coexistence.