Oropouche fever is caused by the Oropouche virus (OROV; Bunyaviridae, Orthobunyavirus), one of the most frequent arboviruses that infect humans in the Brazilian Amazon. This year, an OROV outbreak was identified in Brazil, and its vertical transmission was reported, which was associated with fetal death and microcephaly. We describe the clinical manifestations identified in three cases of congenital OROV infection with confirmed serology (OROV-IgM) in the mother-newborn binomial. One of the newborns died, and post-mortem molecular analysis using real-time RT-qPCR identified the OROV genome in several tissues. All three newborns were born in the Amazon region in Brazil, and the mothers reported fever, rash, headache, myalgia, and/or retro-orbital pain during pregnancy. The newborns presented with severe microcephaly secondary to brain damage and arthrogryposis, suggestive of an embryo/fetal disruptive process at birth. Brain and spinal images identified overlapping sutures, cerebral atrophy, brain cysts, thinning of the spinal cord, corpus callosum, and posterior fossa abnormalities. Fundoscopic findings included macular chorioretinal scars, focal pigment mottling, and vascular attenuation. The clinical presentation of vertical OROV infection resembled congenital Zika syndrome to some extent but presents some distinctive features on brain imaging and in several aspects of its neurological presentation. A recognizable syndrome with severe brain damage, neurological alterations, arthrogryposis, and fundoscopic abnormalities can be associated with in utero OROV infection.

Introduction: The recent Zika virus(ZIKV) epidemic in Brazil was characterized by a range of different clinical presentations, particularly microcephaly, Guillain-Barré syndrome, and death. In this context, we determined the causal relationship between fatal microcephaly cases and ZIKV infection. Methods: Twelve fatal cases of neonates, whose mothers were infected with ZIKV during pregnancy, were examined; cases included nine neonatal deaths due to microcephaly, one miscarriage, and two stillbirths. Tissue samples were obtained from all cases at necropsy and were submitted for virological investigation (RT-qPCR and virus isolation) and/or histopathology (hematoxylin and eosin staining) and immunohistochemical assay for the detection of ZIKV antigens. Results: ZIKV antigens and/or ZIKV RNA were detected in tissue samples of all 12 cases examined. ZIKV was recovered in one case. Results of the virological and immunohistochemical analyses, as well as the anatomic abnormalities and histopathologic changes observed at necropsy on the 12 fatal cases, are presented. Conclusions: Data from these 12 cases provide strong evidence of the causal relationship between ZIKV and congenital disease in fetuses of women who were infected with the virus during pregnancy.

Because of its ecological characteristics, the Caxiuanã National Forest (FLONA) is a potential area of arbovirus circulation. The present study aimed to investigate the occurrence of arbovirus transmission cycles at FLONA de Caxiuanã. Five field trips were performed to capture mosquitoes and sylvatic vertebrates. For these vertebrates, we attempted viral isolation by cell monolayer inoculation from blood, and hemagglutination inhibition and further seroneutralization assays from sera. For mosquitoes, we performed tests of viral genome detection. A total of 338 vertebrates were captured, and the greatest representative was birds (251/74.26%). A total of 16,725 mosquitoes were captured, distributed among 56 species. There were no viruses isolated by newborn mouse inoculation. Among birds, antibodies against Ilheus virus were the most prevalent. Catu virus, Caraparu virus, and Mucambo virus were the most prevalent among mammals and reptiles. Fragments of Mucambo virus, Ilheus virus, Bussuquara virus, and Rocio virus genome were detected in a pool of mosquito samples. These results of the study suggest the occurrence of arbovirus transmission cycles in the FLONA of Caxiuanã. The proximity of human populations with elements, involved in transmission cycles, makes surveillance necessary in this population to avoid dispersion of arboviruses to naïve locations.

Yellow fever (YF) is a pansystemic disease caused by the yellow fever virus (YFV), the prototype species of the family Flaviviridae and genus Flavivirus, and has a highly complex host-pathogen relationship, in which endothelial dysfunction reflects viral disease tropism. In this study, the in situ endothelial response was evaluated. Liver tissue samples were collected from 21 YFV-positive patients who died due to the disease and five flavivirus-negative controls who died of other causes and whose hepatic parenchyma architecture was preserved. Immunohistochemical analysis of tissues in the hepatic parenchyma of YF cases showed significantly higher expression of E-selectin, P-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and very late antigen-4 in YFV-positive cases than in flavivirus-negative controls. These results indicate that endothelium activation aggravates the inflammatory response by inducing the expression of adhesion molecules that contribute to the rolling, recruitment, migration, and construction of the inflammatory process in the hepatic parenchyma in fatal YF cases.