Retrospective molecular investigation of Mayaro and Oropouche viruses at the human-animal interface in West-central Brazil, 2016-2018.

Mayaro virus (MAYV, Togaviridae) and Oropouche orthobunyavirus (OROV, Peribunyaviridae) are emerging enzootic arboviruses in Latin America. Outbreaks of febrile illness associated with MAYV and OROV have been reported among humans mainly in the northern region of Brazil since the 1980s, and recent data suggest these viruses have circulated also in more populated areas of western Brazil. MAYV shares mosquito vectors with yellow fever virus and it has been historically detected during yellow fever epidemics. Aiming to investigate the transmission of OROV and MAYV at the human-animal interface during a yellow fever, chikungunya and Zika outbreaks in Brazil, we conducted a retrospective molecular investigation in 810 wild and domestic animals, 106 febrile patients, and 22.931 vectors collected from 2016 to 2018 in Cuiaba and Campo Grande metropolitan regions, western Brazil. All samples tested negative for OROV and MAYV RNA by RT-qPCR. Findings presented here suggest no active circulation of MAYV and OROV in the sampled hosts. Active surveillance and retrospective investigations are instrumental approaches for the detection of cryptic and subclinical activity of enzootic arboviruses and together serve as a warning system to implement appropriate actions to prevent outbreaks.

Neurological infection by chikungunya and a triple Arbovirus co-infection in Mato Grosso, Central Western Brazil during 2019.

BACKGROUND: Neurological viral infection is frequently associated to enterovirus, herpesvirus and arboviruses. These infections may cause severe clinical outcomes, long lasting sequelae or death. Few studies have addressed viral neurological infections etiology in Brazil. OBJECTIVES: Identification of viruses in the cerebral spinal fluid (CSF) of human neurological infections suspected of viral etiology during January and May 2019 in Midwestern Brazil. MATERIALS AND METHODS: Clinical, laboratory and epidemiological information was gathered from medical records. In addition, an aliquot of the sampled CSF was subjected to viral RNA/DNA extraction, randomic dscDNA amplification by PCR, DNA purification and Ilumina HiSeq 2500 sequencing. RESULTS: Six viral genomes belonging to Chikungunya virus (CHIKV) East-Central-South African (ECSA) genotype (10.834-11.804 nt in length) confirmed lately by RT-PCR for CHIKV envelope were present in all six liquor samples. These genomes present two mutations, nsP2:T31I and nsP3:A388V, shared with other Mato Grosso State strains from 2019, not present in sequences of the virus from previous years obtained in the State. One case was a triple co-infection also confirmed through RT-PCR, with Dengue virus serotype 4 genotype II (NS5; 874 nt) and Oropouche virus genotype IA (segment S; 302 nt). CSF was clear and colorless (5/6 patients), with >10% of lymphomononuclear cells (6/6), 1-99 erythrocytes/mm3 (5/6), glucose levels >50 mg/dl (4/5) e > 10 mg/dl of proteins (4/4). One patient evolved to death, and another, a newborn, presented sequelae after recovery. CONCLUSIONS: Despite herpesviruses and enteroviruses are frequent etiologies of neurological infections, the casuistic here reported was associated to arboviruses already known to be responsible for acute febrile illness outbreaks in the state of Mato Grosso, Midwestern Brazil.