Howler monkeys are the reservoir of malarial parasites causing zoonotic infections in the Atlantic forest of Rio de Janeiro.

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Filipe Vieira Santos de Abreu, Edmilson Dos Santos, Aline Rosa Lavigne Mello, Larissa Rodrigues Gomes, Denise Anete Madureira de Alvarenga, Marcelo Quintela Gomes, Waldemir Paixão Vargas, Cesare Bianco-Júnior, Anielle de Pina-Costa, Danilo Simonini Teixeira, Alessandro Pecego Martins Romano, Pedro Paulo de Abreu Manso, Marcelo Pelajo-Machado, Patrícia Brasil, Cláudio Tadeu Daniel-Ribeiro, Cristiana Ferreira Alves de Brito, Maria de Fátima Ferreira-da-Cruz, Ricardo Lourenço-de-Oliveira
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2019
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic
• Online Access: https://doi.org/10.1371/journal.pntd.0007906; https://doaj.org/article/6b44b77e777a46c2a14b475b6f3a6f0a

BACKGROUND:Although malaria cases have substantially decreased in Southeast Brazil, a significant increase in the number of Plasmodium vivax-like autochthonous human cases has been reported in remote areas of the Atlantic Forest in the past few decades in Rio de Janeiro (RJ) state, including an outbreak during 2015-2016. The singular clinical and epidemiological aspects in several human cases, and collectively with molecular and genetic data, revealed that they were due to the non-human primate (NHP) parasite Plasmodium simium; however, the understanding of the autochthonous malarial epidemiology in Southeast Brazil can only be acquired by assessing the circulation of NHP Plasmodium in the foci and determining its hosts. METHODOLOGY:A large sampling effort was carried out in the Atlantic forest of RJ and its bordering states (Minas Gerais, São Paulo, Espírito Santo) for collecting and examining free-living NHPs. Blood and/or viscera were analyzed for Plasmodium infections via molecular and microscopic techniques. PRINCIPAL FINDINGS:In total, 146 NHPs of six species, from 30 counties in four states, were tested, of which majority were collected from RJ. Howler monkeys (Alouatta clamitans) were the only species found infected. In RJ, 26% of these monkeys tested positive, of which 17% were found to be infected with P. simium. Importantly, specific single nucleotide polymorphisms-the only available genetic markers that differentiate P. simium from P. vivax-were detected in all P. simium infected A. clamitans despite their geographical origin of malarial foci. Interestingly, 71% of P. simium infected NHPs were from the coastal slope of a mountain chain (Serra do Mar), where majority of the human cases were found. Plasmodium brasilianum/malariae was initially detected in 14% and 25% free-living howler monkeys in RJ and in the Espírito Santo (ES) state, respectively. Moreover, the malarial pigment was detected in the spleen fragments of 50% of a subsample comprising dead howler monkeys in both RJ and ES. All NHPs were ...