Detection ofPlasmodium vivaxin a liver sample of a howler-monkey: one evidence more in favour of the identity betweenPlasmodium simiumandP. vivax

Abstract

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.

Atlantic Forest Malaria: A Review of More than 20 Years of Epidemiological Investigation

“…Morphological diagnosis through thick smears by health facilities always report infections as being P. vivax despite the high possibility that part of these cases are caused by P. malariae , instead. The epidemiological investigations performed in the affected areas used several molecular techniques, mainly PCR directed to the 18S rRNA gene, but also different techniques of DNA sequencing [ 5 , 26 ].…”

“…Recently, mitochondrial DNA sequencing raised several debates about putative evidence of a zoonotic cycle [ 5 , 22 , 23 , 24 , 25 , 26 ]. When comparing sequences generated by the sequencing systems with those deposited in GenBank and analyzing phylogenetic trees, some studies suggested a transfer of the parasites from the human host to nonhuman primates but not as a fully recognizable zoonosis.…”

“…However, in other settings, bromeliad-malaria continues to be reported in native inhabitants of rural cities every year, often in people that have never left the areas where they were born but exert some kind of professional activity inside the forest [ 2 , 3 , 5 ]. These differences between the transmission sites are being better understood now as epidemiological studies have used molecular tools to differentiate the parasites found in the three Plasmodium hosts (mosquitoes, simians, and humans) in these regions of Brazil [ 5 , 24 , 25 , 26 ].…”