Complexity of malaria transmission dynamics in the Brazilian Atlantic Forest.

Plasmodium malariae and Plasmodium vivax are protozoan parasites that can cause malaria in humans. They are genetically indistinguishable from, respectively, Plasmodium brasilianum and Plasmodium simium, 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 P. brasilianum and P. simium in platyrrhine primates originated from P. malariae and P. vivax in humans. A recent hypothesis proposed the inclusion of Plasmodium falciparum 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 (Aloutta) blood samples (18%, n = 11) showed Plasmodium cytb DNA sequences, one for P. vivax and another for P. malariae. From a total of 9,416 anopheline females, we found 17 pools positive for Plasmodium species with a 18S qPCR assay. Only three showed P. cytb DNA sequence, one for P. vivax and the others for rodent malaria species (similar to Plasmodium chabaudi and Plasmodium berghei). Based on these results, we tested 25 rodent liver samples for the presence of Plasmodium and obtained P. falciparum cytb DNA sequence in a rodent (Oligoryzomys sp.) liver. The findings of this study indicate complex malaria transmission dynamics composed by parallel spillover-spillback of human malaria parasites, i.e. P. malariae, P. vivax, and P. falciparum, in the Brazilian Atlantic forest.

Possible non-sylvatic transmission of yellow fever between non-human primates in São Paulo city, Brazil, 2017-2018.

Yellow Fever (YF) is a severe disease caused by Yellow Fever Virus (YFV), endemic in some parts of Africa and America. In Brazil, YFV is maintained by a sylvatic transmission cycle involving non-human primates (NHP) and forest canopy-dwelling mosquitoes, mainly Haemagogus-spp and Sabethes-spp. Beginning in 2016, Brazil faced one of the largest Yellow Fever (YF) outbreaks in recent decades, mainly in the southeastern region. In São Paulo city, YFV was detected in October 2017 in Aloutta monkeys in an Atlantic Forest area. From 542 NHP, a total of 162 NHP were YFV positive by RT-qPCR and/or immunohistochemistry, being 22 Callithrix-spp. most from urban areas. Entomological collections executed did not detect the presence of strictly sylvatic mosquitoes. Three mosquito pools were positive for YFV, 2 Haemagogus leucocelaenus, and 1 Aedes scapularis. In summary, YFV in the São Paulo urban area was detected mainly in resident marmosets, and synanthropic mosquitoes were likely involved in viral transmission.