Detection of Plasmodium vivax in a liver sample of a howler-monkey: one evidence more in favour of the identity between Plasmodium simium and P. vivax

Introduction: The residual malaria of Atlantic Forest systems in Brazil occurs as an endemic disease with low frequency of cases. The chronological and spatial distance among the cases indicate an absence of fitness to the classical malaria cycle. This peculiar condition raised the suspicion of a reservoir, possibly the non-human primates. Simian and human malaria occur at the same places in that region, and there is already evidence of molecular identity between the simian parasites, Plasmodium simium and Plasmodium brasilianum, and the human parasites, Plasmodium vivax and Plasmodium malariae, respectively. Two different SNPs identified in the COX1 region of the Plasmodium vivax/simium of the Atlantic Forest reinforced its characterization as a zoonotic parasite. This finding supported the development of a PCR-RFLP protocol to identify such polymorphisms, and to monitor zoonotic malaria transmission. Methods: In the present work, we tested the above-mentioned PCR-RFLP protocol in unprecedented mosquitoes and simian samples collected in Espirito Santo State, Brazil (ES). Results: The parasite found in the simian sample was P. vivax, contrary to what the protocol should indicate. In the mosquito samples, the protocol disclosed both forms of the parasite. Conclusion: This result suggests that the previously published pair of SNPs, and, consequently, the PCR-RFLP protocol, are not able to distinguish the dynamics of Plasmodium spp. circulation in the Atlantic Forest endemic area of ES.