Oropouche virus disease

Oropouche virus disease is a viral zoonosis caused by Oropouche virus (OROV), a segmented single-stranded RNA virus classified within the family Peribunyaviridae and genus Orthobunyavirus. First identified in 1955 in Vega de Oropouche, Trinidad and Tobago, the virus is maintained in natural cycles involving non-human primates, sloths, birds, and possibly other vertebrates, with transmission to humans mediated primarily by biting midges (e.g., *Culicoides paraensis*) and secondarily by mosquitoes such as *Aedes serratus*, *Culex quinquefasciatus*, and *Coquillettidia venezuelensis*. The disease is recognized as an arthropod-borne virus (arbovirus) with both sylvatic and urban transmission cycles.

The incubation period typically ranges from 3 to 10 days, with onset of fever followed by headache, myalgia, arthralgia, chills, nausea, vomiting, and occasionally a rubella-like rash or photophobia. Most patients recover fully within 7 days, though prolonged convalescence may occur. Severe manifestations—including aseptic meningitis, encephalitis, and hemorrhagic tendencies—have been reported, particularly in the context of recent outbreaks. In 2024, two fatal cases occurred in previously healthy young adults, and four cases of microcephaly in newborns were documented following maternal infection, suggesting possible vertical transmission. Clinical presentation closely mimics dengue, chikungunya, and Zika, leading to frequent misdiagnosis without laboratory confirmation.

Prior to late 2023, ORD was largely confined to South America and the Caribbean, with high incidence in Brazil, Bolivia, Colombia, Ecuador, Haiti, Panama, Peru, Trinidad and Tobago, French Guiana, and Venezuela—especially near the Amazon rainforest. It was historically the second most common arboviral disease in South America after dengue before the emergence of chikungunya and Zika. Since December 2023, cases have increased significantly and spread to new areas, including seven countries in Latin America and the Caribbean with locally acquired infections. Over half a million cases have been reported since 1955, though many likely went undiagnosed due to limited surveillance capacity and clinical similarity to other arboviruses.

Transmission occurs via the bite of infected hematophagous insects, primarily *Culicoides paraensis* midges, with secondary involvement of *Aedes serratus*, *Culex quinquefasciatus*, and *Coquillettidia venezuelensis* mosquitoes. The virus circulates in a sylvatic cycle among non-human primates, sloths, and birds, and in an urban cycle between vectors and humans. Vertical transmission from mother to fetus has been documented in 2024, and no human-to-human transmission has been confirmed. No evidence supports airborne, fecal-oral, or bloodborne routes in the absence of vector exposure.

Individuals residing in or traveling to endemic areas of the Amazon basin and Caribbean, particularly those with occupational or recreational exposure to forested or peri-urban environments, are at elevated risk. Pregnant individuals face additional concern due to documented vertical transmission and associated adverse outcomes. Previously healthy young adults have been reported to experience severe disease and death in recent outbreaks, indicating that age and underlying health status may influence clinical trajectory. No immunity is known to confer long-term protection, and prior infection does not preclude reinfection.

No vaccine or specific antiviral treatment is available. Prevention relies on vector control measures—including environmental management, insecticide use, and personal protective behaviors (e.g., bed nets, repellents, clothing coverage)—particularly in endemic and newly affected regions. Public health response should include enhanced surveillance, early case detection, and laboratory confirmation to differentiate ORD from other febrile illnesses. Pregnant women in affected areas require special attention due to emerging evidence of fetal risk.

ORD presents a growing public health concern due to its expanding geographic range, increasing severity, and potential for underreporting. Surveillance should prioritize differential diagnosis in patients presenting with acute febrile illness in endemic or newly affected areas, especially where dengue/chikungunya are also circulating. Laboratory confirmation using RT-PCR or real-time RT-PCR is essential, as serologic testing lacks commercial availability and requires high-containment facilities. Reporting of suspected cases, including those with neurological or obstetric complications, should be prioritized to inform outbreak response and guide vector control interventions.

1. 1 WHO Fact Sheet. Oropouche virus disease.
2. 2 Wikipedia. Oropouche fever - Wikipedia.

ICD-10

ICD-11

Total cases

0

Peak month

2026-01

Coverage

1 reporting countries · 2026-01-10 → 2026-05-09