A Case Report of Potential Intrapartum Transmission of Oropouche Virus in an Outbreak in Brazil

To the Editors: The current outbreak of Oropouche fever raised concerns about vertical transmission of Oropouche virus (OROV), with reports of spontaneous abortions, stillbirths and malformations, such as agenesis of the corpus callosum.1 In Espírito Santo state, Brazil, we have also observed evidence of intrapartum transmission, similar to that previously reported in chikungunya, dengue and yellow fever infections, with a neonate presenting clinical manifestations.2 This also corroborates another observation of possible intrapartum transmission involving a symptomatic pregnant woman without laboratory confirmation for OROV infection.3 In the area, surveillance of OROV infection in pregnancy follows specific protocols of the Brazilian Ministry of Health.4 One pregnant woman without underlying medical conditions was notified in 2025, presenting signs and symptoms of Oropouche fever, such as fever, headache and myalgia, at 39 weeks of gestation and had a reverse transcription polymerase chain reaction (RT-PCR) test positive for OROV RNA in serum. After 6 days, she had a spontaneous rupture of the membranes 8 hours before the vaginal delivery. The Apgar score of the neonate was 9 at 1 and 5 minutes after birth. No laboratory tests, such as RT-PCR, immunohistochemistry and histopathology, were performed with placental tissue, amniotic fluid or cord blood. The neonate presented with fever and agitation at 2 days of life and had a positive RT-PCR result for OROV RNA in the serum sample. Neonate’s laboratory tests were negative for dengue, chikungunya, zika, toxoplasmosis, rubella and herpes. The postpartum discharge occurred at 3 days of life. However, at 8 days of life, the neonate was readmitted to the hospital with fever and agitation, indicating a possible recurrence of Oropouche fever symptoms. Then, the neonate was discharged without presenting clinical manifestations (Table 1). TABLE 1. - Clinical Description of the Case of Possible Intrapartum Transmission of Oropouche virus Day* Clinical Observations 1 Pregnant woman: 39th gestational week 20 years old; no comorbidities; urban areaPrenatal tests: Negative: hepatitis B and C, Syphilis, HIV, toxoplasmosisClinical manifestations: Fever, headache, myalgia, back pain 3 Pregnant woman: 39th gestational week Molecular biology tests with serum samples: Negative: dengue, zika, chikungunya, herpes, varicella zoster; syphilis Positive: Oropouche 6 Delivery: 40th gestational week Vaginal birth, 8 hours after placental rupture, fluid meconiumPregnant woman: Temperature of 36.6 °C, heart rate of 78 bpm, respiratory rate of 17 rpmNeonate: Female; birth weight of 3310 g; birth height of 50 cm; head circumference of 35 cm; Apgar 1st/5th minutes of life of 9/9; temperature of 36.8 ºC Normal skin parameters: ruddy; hydrated; acyanotic; anicteric Normal neural parameters: active; reactive; normal reflex; flat and normotense fontanelle; no seizures Normal morphological parameters: eyes, nose and mouth without abnormalities; ears with normal implantation; intact clavicles Normal cardiovascular parameters: regular heart rhythm in 2 beats; no murmurs; full and symmetrical brachial and femoral pulses; adequate perfusion Normal respiratory parameters: physiological breath sounds; no adventitious noises; no respiratory distress; Eupnea Normal abdominal parameters: flaccid abdomen; air sounds present; painless; no masses or visceromegaly; umbilical stump in good aspect Typical female genitalia Ortolani negative 0 Neonate: 1st day of life Normal clinical parameters: No changes in skin, neural, morphological, cardiovascular, respiratory and abdominal parameters Temperatures: 36.5 ºC; 36.7 ºC Diuresis: present Breastfeeding: adequateMolecular biology tests with serum samples: Negative: dengue, zika, chikungunya, herpes, varicella zoster; syphilis Positive: Oropouche 1 Neonate: 2nd day of life Normal clinical parameters: No changes in skin, neural, morphological, cardiovascular, respiratory and abdominal parametersClinical alterations: Highest temperature: 38.2 ºC (other measurements: 36.6 ºC and 37.2 ºC) Heart rate: 120 bpm Respiratory rate: 50 rpm Doppler echocardiogram: patent foramen ovaleClinical management: Antipyretic 2 Neonate: 3rd day of life Normal clinical parameters: No changes in skin, neural, morphological, cardiovascular, respiratory and abdominal parameters Temperature: 36.5 ºC Medical discharge 6 Neonate: 7th day of life Fever of 38 °C 7 Neonate: 8th day of life Hospital admission No fever No seizures Medical dischargeLaboratory results: Blood test: hemoglobin of 16.2; hematocrit of 46.8; leukocytes of 17,890; platelet of 226,000; C-reactive protein <6; glucose of 98 Urine test: pH of 6.5; rare leukocytes; absent red cells; Scarce flora 10 Neonate: 11th day of life Normal transfontanelle ultrasound *Day after the onset of Oropouche fever symptoms. This case warns about the possible consequences of OROV infection in pregnant women at the end of gestation, with intrapartum maternal viremia probably contributing to vertical transmission. Neonatal infection may have significant consequences, considering the neurotropic tendency of OROV and previous reports of the disease’s neurologic manifestations, such as meningitis or encephalitis, that can lead to death.5 Medical follow-up of the neonates affected by the infection is necessary to ensure timely and appropriate interventions. Additionally, further studies are needed to assess the risks of OROV infection at all stages of pregnancy for both pregnant women and their newborns.