Complexity of malaria transmission dynamics in the Brazilian Atlantic Forest.

and are protozoan parasites that can cause malaria in humans. They are genetically indistinguishable from, respectively, and , i.e. parasites infecting New World non-human primates in South America. In the tropical rainforests of the Brazilian Atlantic coast, it has long been hypothesized that . and . in platyrrhine primates originated from . and . in humans. A recent hypothesis proposed the inclusion of into the transmission dynamics between humans and non-human primates in the Brazilian Atlantic tropical rainforest. Herein, we assess the occurrence of human malaria in simians and sylvatic anophelines using field-collected samples in the Capivari-Monos Environmental Protection Area from 2015 to 2017. We first tested simian blood and anopheline samples. Two simian () blood samples (18%,  = 11) showed DNA sequences, one for . and another for . . From a total of 9,416 anopheline females, we found 17 pools positive for species with a qPCR assay. Only three showed DNA sequence, one for . and the others for rodent malaria species (similar to and ). Based on these results, we tested 25 rodent liver samples for the presence of and obtained . DNA sequence in a rodent ( sp.) liver. The findings of this study indicate complex malaria transmission dynamics composed by parallel spillover-spillback of human malaria parasites, i.e. . , . , and . , in the Brazilian Atlantic forest.