Plasmodium infection in non-human primates from Atlantic forest: who cares?

Background: In the context of malaria elimination in Brazil, outbreaks of autochthonous cases of the disease described in extra-Amazon region, such as reported cases in the Atlantic forest, has increased importance. In this scenario, NHPs as a source for Plasmodiuminfections in humans are a challenge for malaria elimination. Plasmodium simium is morphologically, genetically and immunologically similar to the human parasite P. vivax. Therefore, molecular studies of simian plasmodia species are paramount to understand phylogenetic relationships between P. simium and P. vivax and clarify the introduction of these parasites in the South America. Materials and Methods: We studied wild and captivity NHPs from Atlantic Forest. Thirty wild primates were captured in Joinville, Santa Catarina in 2015 and about 280 NHPs housed in the Centro de Primatologia do Rio de Janeiro (CPRJ) were sampled between 2011 and 2016. The samples were screened for the presence of Plasmodium using optical microscopy and nested PCR for detection of 18S SSU rRNA gene. Here, we investigate the phylogenies and genetic diversity among these parasite species using DNA sequencing and microsatellite genotyping. Results: Wild NHPs from Joinville shows a high infection rate of 76.6% in the molecular diagnosis in 2015. The result of captive animals from CPRJ identified an infection rate of 30% in 2011, 25% in January/2015, 6.6% January/2016. The sequencing of a small fragment of the 18S SSU rRNA encoding gene showed a high genetic similarity between P. vivax and P. simium, as demonstrated by other authors. This high identity is also observed in the phylogenetic reconstruction of P. simium isolates studied here. Three loci of microsatellite and two polymorphic blocks of PvMSP-1 showed that there is a great genetic diversity among the circulating parasites. Conclusions: The reported P. simium infection in wild and captivity NHPs suggests that infection can be favored by the presence of vectors and the proximity between hosts of malaria and may also highlight the potential of zoonotic transmission of the parasite in areas of the Atlantic forest.