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.

Evaluation of the Diversity of Culicidae Vectors of the Sylvatic Yellow Fever Virus in Atlantic Forest Remnants with the Use of Ovitraps and Bamboo Traps.

Mosquitoes transmit several pathogens in tropical regions, especially in forest areas. The diseases caused by these pathogens include malaria and several arboviruses such as yellow fever. Brazil has the largest endemic area in the world for yellow fever. Many factors can affect the sylvatic cycle of the disease, shifting it into human-inhabited areas. This study aims to examine the oviposition behavior of mosquito species that are effective or potential vectors of the yellow fever virus and which colonize bamboo traps and ovitraps installed at different heights. The positions of the traps in the strata were changed every 15 days. The collection of immature stages (eggs, larvae, and pupae) was performed every 2 weeks for 12 months from August 2018 to July 2019 in the city of Nova Iguaçu, state of Rio de Janeiro, Brazil, in an area near the Tinguá Biological Reserve (REBIO) in the districts of Adrianópolis and Rio D'ouro. Statistical tests were used to compare oviposition at each stratum, and correlation tests showed the relationship between the presence of eggs and immature mosquitoes (larvae and pupae) and temperature, precipitation, and trap type. The diversity was calculated for each trap type and height, as well as the dry and rainy seasons. During the sampling period, 3929 eggs and 4953 larvae and pupae were collected. The traps installed in the high strata remained empty when traps on the ground were installed at the same time, although not when they were installed on their own. The results obtained with this new proposed methodology suggest that diversity is greatest in the rainy season and in bamboo traps for either stratum. Furthermore, this study suggests that mosquitoes begin searching for breeding sites at ground level. Higher levels may be occupied due to the absence or impermanence of other breeding sites.