Oropouche virus infection in pregnancy: emerging evidence on vertical transmission and perinatal outcomes

To synthesize current evidence on Oropouche virus infection during pregnancy, with particular emphasis on transmission dynamics, clinical presentation, diagnostic challenges, and emerging data on vertical transmission and adverse fetal and perinatal outcomes.

A narrative review of the literature was conducted to summarize available data on Oropouche virus infection in pregnancy. Searches were performed in PubMed/MEDLINE, Scopus, Web of Science, Embase, SciELO, and LILACS, complemented by official reports from the World Health Organization (WHO), Pan American Health Organization (PAHO), Centers for Disease Control and Prevention (CDC), and the Brazilian Ministry of Health. The search strategy included combinations of the following keywords: "Oropouche virus", "Oropouche fever", "pregnancy", "vertical transmission", "congenital infection", "fetal outcomes", "arbovirus", and "perinatal outcomes". Original studies, case reports, case series, reviews, surveillance reports, and clinical guidelines published in English, Portuguese, or Spanish were considered. No formal quality assessment or meta-analysis was performed, consistent with a narrative review design.

Oropouche virus is an emerging arboviral infection in Latin America, with a rapidly increasing number of cases reported in Brazil and neighboring countries. Transmission occurs mainly via Culicoides paraensis midges and Culex mosquitoes. Although infection is usually self-limiting, clinical manifestations frequently overlap with other arboviral diseases, complicating diagnosis. Growing evidence indicates that vertical transmission can occur, with confirmed cases associated with fetal demise and congenital anomalies, including microcephaly, ventriculomegaly, corpus callosum dysgenesis, cerebral atrophy, posterior fossa abnormalities, and arthrogryposis. Viral neurotropism and detection of viral RNA in placental and fetal tissues support a plausible teratogenic potential. Diagnostic confirmation relies on RT-PCR during the acute phase and serological testing thereafter. In pregnancy, management requires referral to high-risk obstetric care, serial fetal imaging, particularly focused on central nervous system evaluation, and multidisciplinary perinatal planning.

Oropouche virus infection should be recognized as an emerging threat to maternal and fetal health. Accumulating evidence of vertical transmission and congenital involvement underscores the need to include Oropouche virus in the differential diagnosis of febrile illness during pregnancy in endemic areas. In the absence of specific treatment or licensed vaccines, prevention relies on vector control and personal protective measures. Strengthened surveillance systems, standardized diagnostic protocols, and prospective studies are urgently needed to clarify the magnitude of fetal risk, mechanisms of vertical transmission, and long-term outcomes of congenitally exposed infants.