What is Oropouche Virus?

Oropouche virus disease is an arboviral disease caused by the Oropouche virus (OROV), a segmented single-stranded RNA virus that is part of the genus Orthobunyavirus of the Peribunyaviridae family. The virus has been found to circulate in Central and South America and the Caribbean. OROV can be transmitted to humans primarily through the bite of the Culicoides paraensis midge, found in forested areas and around water bodies, or certain Culex quinquefasciatus mosquitos. It is suspected that viral circulation includes both epidemic and sylvatic cycles. In the sylvatic cycle, primates, sloths, and perhaps birds are the vertebrate hosts, although a definitive arthropod vector has not been identified. In the epidemic cycle, humans are the amplifying host and OROV is transmitted primarily through the bite of the Culicoides paraensis midge.The incubation period for Oropouche virus disease is 3–10 days. Typically, disease starts with the abrupt onset of fever (38-40°C) with headache (often severe), chills, myalgia, and arthralgia.Other signs and symptoms include photophobia, dizziness, retroorbital or eye pain, nausea and vomiting, or maculopapular rash that starts on the trunk and goes to the extremities. Less common symptoms can include conjunctival injection, diarrhea, severe abdominal pain, and hemorrhagic symptoms (e.g., epistaxis, gingival bleeding, melena, menorrhagia, and petechiae).Symptoms typically last less than a week (2–7 days). However, in up to 60% of patients, symptoms can reoccur a few days or even weeks later. Similar symptoms are reported on relapse.The symptoms of Oropouche virus disease can be similar to symptoms of dengue, chikungunya, or Zika viruses, or malaria.On July 17, 2024, the Pan American Health Organization (PAHO) issued an epidemiological alert about cases in Brazil of vertical transmission of Oropouche virus associated with adverse pregnancy outcomes, including fetal deaths and congenital abnormalities. These cases are under investigation. CDC is working with PAHO and other international partners to learn more about the risks of Oropouche during pregnancy.