What is Oropouche virus disease?

Oropouche virus disease (also called Oropouche fever or Oropouche disease) is an arboviral illness caused by Oropouche virus (OROV) — a bunyavirus transmitted primarily by Culicoides paraensis biting midges. First identified in Trinidad in 1955, it has caused periodic epidemics in the Amazon basin affecting hundreds of thousands of people over decades. In 2024, Brazil experienced its largest-ever Oropouche outbreak (10,000+ confirmed cases), which spread to multiple other Latin American countries and caused globally significant alarm with the first confirmed cases of vertical (mother-to-fetus) transmission causing fetal deaths and severe congenital anomalies.

How is Oropouche transmitted?

Primary vector: Culicoides paraensis — a tiny biting midge (1-2mm, smaller than a standard mosquito) that breeds in decaying plant matter (cacao husks, banana stems, rotting vegetation). Culex mosquitoes are secondary vectors in some settings. Important: Culicoides midges are much smaller than mosquitoes and can pass through standard mosquito net mesh — fine mesh nets and tightly woven clothing are required. OROV is transmitted when an infected vector takes a blood meal from a human host. Unlike dengue or Zika, OROV is NOT known to spread by Aedes aegypti (the most widely distributed urban mosquito vector globally).

What are the symptoms?

Oropouche presents with sudden onset fever (38-40°C), severe headache (often retroorbital), myalgia (muscle pain), arthralgia, photophobia, nausea and vomiting — clinically identical to dengue fever. A maculopapular rash occurs in approximately 50% of cases. Duration: typically 3-7 days; most patients recover completely. Serious complications: aseptic meningitis and encephalitis occur in a minority. Case fatality rate: very low (<0.1%) in immunocompetent, non-pregnant adults. Pregnant women: significant risk of adverse fetal outcomes.

What was the 2024 congenital Oropouche discovery?

In May-August 2024, during Brazil's unprecedented Oropouche outbreak, Brazilian health authorities documented the first confirmed cases of vertical (transplacental) Oropouche virus transmission. Reported outcomes: intrauterine fetal deaths; cases of microcephaly (abnormally small head/brain); other severe congenital anomalies including brain abnormalities. This was analogous to the Zika virus discovery of 2015-2016 that led to WHO declaring a PHEIC. As of 2025, WHO and PAHO advise that pregnant women should avoid travel to active Oropouche outbreak areas and that pregnant women in affected areas should use strict personal protection against midge bites.

Is Oropouche a risk in Europe?

Oropouche virus is not currently established in Europe — there is no Culicoides paraensis vector population in Europe capable of sustaining OROV transmission. However, imported cases in returning travellers have been confirmed in multiple European countries. ECDC and WHO actively monitor OROV for: travellers returning from affected Latin American countries; pregnant travellers (highest risk group); the possibility of future vector adaptation to European Culicoides species (theoretical, unconfirmed). Travel health advisories should be checked for affected countries (Brazil, Cuba, Colombia, Peru, Bolivia).

How does GMJ News cover Oropouche?

GMJ News covers WHO 2024 Oropouche disease emergency alert, the unprecedented Brazil outbreak, the congenital OROV discovery (the Zika parallel), Culicoides midge vs mosquito vector distinction, travel advisories for pregnant women, dengue/OROV clinical differentiation, and ECDC monitoring. Oropouche represents the most important new arboviral emergence of 2024 — an essential emerging disease topic for GMJ and PHIG's global health coverage.

Home › Topics › Oropouche Virus Disease

Oropouche Virus Disease

Q: What was the 2024 congenital Oropouche discovery?

In May-August 2024, during Brazil's unprecedented Oropouche outbreak, Brazilian health authorities documented the first confirmed cases of vertical (transplacental) Oropouche virus transmission. Reported outcomes: intrauterine fetal deaths; cases of microcephaly (abnormally small head/brain); other severe congenital anomalies including brain abnormalities. This was analogous to the Zika virus discovery of 2015-2016 that led to WHO declaring a PHEIC. As of 2025, WHO and PAHO advise that pregnant women should avoid travel to active Oropouche outbreak areas and that pregnant women in affected areas should use strict personal protection against midge bites.

Q: Is Oropouche a risk in Europe?

Oropouche virus is not currently established in Europe — there is no Culicoides paraensis vector population in Europe capable of sustaining OROV transmission. However, imported cases in returning travellers have been confirmed in multiple European countries. ECDC and WHO actively monitor OROV for: travellers returning from affected Latin American countries; pregnant travellers (highest risk group); the possibility of future vector adaptation to European Culicoides species (theoretical, unconfirmed). Travel health advisories should be checked for affected countries (Brazil, Cuba, Colombia, Peru, Bolivia).

Q: How does GMJ News cover Oropouche?

GMJ News covers WHO 2024 Oropouche disease emergency alert, the unprecedented Brazil outbreak, the congenital OROV discovery (the Zika parallel), Culicoides midge vs mosquito vector distinction, travel advisories for pregnant women, dengue/OROV clinical differentiation, and ECDC monitoring. Oropouche represents the most important new arboviral emergence of 2024 — an essential emerging disease topic for GMJ and PHIG's global health coverage.

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Oropouche virus disease — caused by Oropouche virus (OROV, a bunyavirus transmitted by Culicoides paraensis biting midges and Culex mosquitoes) — erupted in 2024 as a major global health alert when Brazil reported its largest-ever Oropouche outbreak (over 10,000 confirmed cases and spread to Cuba, Bolivia, Colombia and Peru), prompting WHO and US CDC advisories, and — most alarmingly — the first confirmed cases of vertical (mother-to-fetus) transmission causing fetal death and severe congenital abnormalities, paralleling the Zika virus discovery that shocked the world in 2015-2016 (WHO 2024). With no approved vaccine or antiviral, Oropouche is now a WHO-monitored emerging arboviral disease of global concern.

Key messages

2024 — largest outbreak ever; congenital transmission confirmed

The 2024 Brazil Oropouche outbreak was the largest ever recorded (10,000+ confirmed cases) and for the first time confirmed vertical (mother-to-fetus) transmission causing fetal deaths and severe congenital anomalies — prompting WHO and US CDC advisories for pregnant travellers to Latin America (WHO 2024).

Culicoides biting midge — not mosquito-transmitted

The primary vector of Oropouche virus is Culicoides paraensis — a tiny biting midge (no-see-um) approximately 1-2mm long — NOT the Aedes or Culex mosquitoes that transmit dengue, Zika and yellow fever. Standard mosquito repellents and nets have reduced efficacy against the smaller midge.

Dengue-like illness — clinically indistinguishable

Oropouche presents identically to dengue: sudden fever, severe headache, myalgia, arthralgia, photophobia, nausea and vomiting. In regions where both circulate, clinical differentiation is impossible without PCR testing. Rash occurs in approximately 50% of cases.

No vaccine, no antiviral — supportive care only

No approved vaccine or antiviral treatment exists for Oropouche. Management is entirely supportive: fever reduction, hydration, rest. Aspirin and NSAIDs should be avoided (haemorrhagic risk). WHO and ECDC monitoring ongoing.

Pregnant women — the critical risk group

The 2024 discovery of congenital Oropouche infection — similar to the Zika virus revelation of 2015 — means pregnant women should be specifically warned against travel to active outbreak areas. Evidence suggests OROV can cross the placenta and cause fetal death, microcephaly and other severe anomalies.

Europe and North America — travel-imported cases

Return travel-associated Oropouche cases have been reported in multiple European countries and the US from travellers returning from Brazil, Cuba and other affected Latin American countries. ECDC and CDC have issued travel health advisories.

Key statistics

10K+

confirmed Oropouche cases in Brazil 2024 — largest outbreak ever

WHO/Brazil 2024

2024

year first confirmed congenital Oropouche infections (fetal deaths, anomalies)

WHO/Brazil 2024

Multiple

countries affected in 2024: Brazil, Cuba, Bolivia, Colombia, Peru, plus travel-imported cases

WHO/PAHO 2024

Culicoides

paraensis biting midge — primary vector (not Aedes/Culex mosquito)

WHO

approved vaccine or antiviral for Oropouche — supportive care only

WHO 2024

WHO monitored

active WHO/PAHO monitoring and ECDC travel advisories 2024-2025

WHO/ECDC 2024

Oropouche outbreak cases — Brazil 2024 by epidemiological week (WHO/Brazil MOH)

Source: WHO/Brazil Ministry of Health 2024. The 2024 outbreak far exceeded any previous Oropouche epidemic.

Glossary of key terms

Oropouche virus (OROV)
WHO/PAHOAn RNA virus belonging to the genus Orthobunyavirus, family Peribunyaviridae. Named after the Oropouche River in Trinidad, where it was first isolated in 1955 from a febrile forest worker. Three genome segments (L, M, S) encoding RNA-dependent RNA polymerase, envelope glycoproteins and nucleoprotein. OROV has caused periodic large epidemics in the Amazon basin since 1960.

Culicoides paraensis (midge vector)
WHO/EntomologyA biting midge approximately 1-2mm in length — one of the smallest haematophagous (blood-feeding) insects. Primary Oropouche vector in urban and periurban settings. Culicoides breed in moist, decaying organic matter (cacao husks, banana and plantain stems — common in Amazon agricultural settings). KEY PRACTICAL POINT: standard mosquito nets (wide mesh) do not prevent Culicoides biting — fine mesh nets or tightly woven fabric is required.

Congenital Oropouche (2024 discovery)
WHO/Brazil 2024In 2024, Brazilian health authorities and WHO confirmed the first documented cases of vertical (transplacental) Oropouche transmission — analogous to the Zika virus pandemic revelation of 2015. Reported outcomes: intrauterine fetal death; fetal microcephaly; other severe congenital anomalies. The full teratogenic spectrum of OROV is being urgently characterised. As of 2025, WHO and PAHO advise pregnant women to avoid travel to active outbreak areas.

Differential diagnosis from dengue
WHO/ClinicalOropouche and dengue have clinically indistinguishable presentations in the acute phase: sudden fever; severe retroorbital or bifrontal headache; myalgia; arthralgia; photophobia; nausea/vomiting; maculopapular rash (in approximately 50% of OROV cases). Laboratory differentiation: RT-PCR (gold standard in first 5 days of illness); serology (after day 7 — but cross-reactivity between bunyaviruses can complicate interpretation). In co-endemic areas (Amazon basin, where dengue, Zika, chikungunya and OROV all circulate), multiplex PCR panels are essential.

Arboviral disease surveillance
WHO/PAHOArboviruses (arthropod-borne viruses) transmitted by insect vectors include dengue, Zika, chikungunya, yellow fever and now Oropouche as priority emerging threats. WHO/PAHO coordinates integrated arboviral surveillance across the Americas. ECDC monitors arboviral travel importations to Europe. The 2024 Oropouche outbreak demonstrated that arboviruses previously considered regional threats can rapidly expand geographically with human movement and changing vector distributions.

OROV history — 1955 to 2024
WHOOROV first isolated in 1955 (Trinidad). First large epidemic: Belém, Brazil, 1960 (11,000 cases). Multiple epidemics in Brazilian Amazon 1960s-2000s (up to 500,000 estimated cases historically). Genotype I: Amazon/Caribbean; Genotype II: Brazilian coast. The 2024 epidemic marked unprecedented geographic expansion beyond the Amazon basin — reaching coastal Brazil, Cuba and other Caribbean/Latin American countries — and the alarming confirmation of pregnancy-related risks.