key points
- Oropouche virus disease is an emerging arboviral disease transmitted primarily by midges (Culicoides), responsible for an acute febrile syndrome that is most often benign.
- An epidemic has been ongoing since 2024 in Latin America and the Caribbean, with continued transmission in 2025 and imported cases among travellers.
- Symptoms include sudden fever, headaches and muscle pain, with rare neurological forms and a possible risk signal in pregnant women.
- Prevention relies on protection against insect bites, as no vaccine or specific treatment is currently available.
Disease
La Oropouche virus disease is an acute infection due to Oropouche virus (OROV), belonging to the arbovirus family. This virus is transmitted to humans primarily through the bite of midges of the genus CulicoidesIn the majority of infected individuals, the infection manifests as a non-specific febrile syndrome Clinically similar to other arboviral infections such as dengue or chikungunya, this can delay diagnosis. More severe forms, particularly neurological and hemorrhagic ones, are possible but remain rare.
Oropouche in the world
The Oropouche virus was discovered in 1955 near the Oropouche River in Trinidad and Tobago. Historically, the disease was endemic to the Amazon basin and certain tropical areas of South America and the Caribbeanwith sporadic episodes since the 1960s. However, since late 2023, an unprecedented epidemic has developed in Latin America, characterized by a sustained increase in the number of confirmed cases, a geographical expansion and the emergence of outbreaks in areas not historically affectedIn 2024, several countries reported local transmission, including Brazil, Bolivia, Colombia, Cuba, Guyana, Peru and the Dominican Republic, with several thousand confirmed cases and some deaths associated with complications of the infection.
The available epidemiological data for 2025 show that More than 12,000 confirmed cases were reported between January and July 2025 in at least 11 countries in the Americas.with local transmission in seven of them and imported cases in others, reflecting a continued spread of this virusThe spread of the infection beyond the Amazon basin can be explained by environmental factors such as climate change, deforestation and uncontrolled urbanization, which promote the increase of vector populations and human-vector contact.
Furthermore, it is an RNA virus that frequently reassorts, and a recent reassortant (OROVBR-2015-2024) could explain the expansion of its circulation area and its current emergence in South America and the Caribbean. The possibility of an epidemic outbreak and emergence in the French Antilles and French Guiana also arises.
In addition, imported cases have been observed among travelers returning from Latin America to countries in North America and Europe, highlighting the importance of increased vigilance in the context of international travel.
The clinic
In affected patients, the disease usually begins after a incubation period of 3 to 10 days by high fever of sudden onset, accompanied by severe headaches, muscle pain, joint pain, chills, intense fatigue and sometimes transient gastrointestinal symptomsThe evolution is, in most cases benign, with spontaneous resolution of symptoms in 2 to 7 days., but relapses can occur after a period of improvement (biphasic pattern).
In a minority of patients, neurological complications Cases such as meningitis, encephalitis, or various neurological disorders have been reported, requiring specialized hospital care. Furthermore, for the first time, maternal-fetal forms have been described, along with a link to fetal deaths. in utero and validated fetal malformations. The question of sexual transmission also arises, which still requires in-depth studies to be confirmed.
The diagnosis
Clinical diagnosis is complex given the nonspecific symptoms common to most arboviral diseases, including dengue and Zika virus.
The diagnosis of Oropouche virus disease is based on the combination of clinical, epidemiological and biological criteriaClinically, it should be considered in the presence of a acute febrile syndrome with fever, headache and muscle pain, particularly among people residing in or returning from known transmission areas.
From a biological standpoint, a virological diagnosis is necessary, by quantitative reverse transcription (RT)-PCR up to the 7thrd day following the onset of symptoms and/or by serology from the 5th day. It is essential to include in the differential diagnosis the other common arboviruses in the same geographical areas (dengue, Zika, chikungunya), as well as other causes of tropical fever.
For pregnant women who have traveled to a risk area where an ongoing outbreak has been documented and who have not presented any symptoms:
- to carry out pregnancy monitoring according to the usual recommendations;
- to only discuss carrying out an RT-PCR test and/or an OROV serology test in those who have travelled to a territory where there is a proven epidemic;
- In the event of a diagnosis of fetal anomalies during pregnancy monitoring, it is important to remind the healthcare team about travel undertaken and to refer the patient to a prenatal diagnostic center where OROV infection testing will be offered and specialized follow-up will be arranged.
In the event of the onset of compatible symptoms while in the area or within two weeks of returning from a risk zone where an ongoing epidemic has been documented:
- consult for a diagnostic assessment including the search for OROV (by plasma RT-PCR and/or serology) and its differential diagnoses.
In case of diagnostic confirmation:
- not to take acetylsalicylic acid or other non-steroidal anti-inflammatory drugs;
- for men to use condoms or abstain from unprotected sex with a woman of childbearing age for 6 weeks after the onset of symptoms;
- to report all cases of OROV infection to the Regional Health Agency;
- for pregnant women, to direct them to a prenatal diagnostic center where the monitoring of fetal viability and the screening for fetal morphological anomalies will be organized;
- for newborns of infected mothers, to organize specialized pediatric follow-up including a diagnostic assessment (RT-PCR and/or serology) whose negative result does not exclude the diagnosis, a morphological assessment, and, in case of detection of morphological abnormalities, to complete the etiological assessment and complications and to organize multidisciplinary follow-up;
The treatment
Nowadays, No specific antiviral treatment is available. for Oropouche virus disease. Management is therefore essentially symptomatic, based on the Rest, hydration, and treatment of fever and pain primarily with paracetamol. Non-steroidal anti-inflammatory drugs and aspirin should be used with caution, or even avoided, until diagnoses of other potentially hemorrhagic arboviral infections such as dengue have been ruled out. Severe or complicated forms, particularly those with neurological involvement, require hospitalization and multidisciplinary care to monitor and treat complications.
Prevention
On a collective level, the programs of epidemiological surveillance, vector control and awareness-raising Local populations are essential to reducing the impact of the epidemic. To date, No vaccine is available against Oropouche virus infection, and research continues to better understand the determinants of its transmission and to develop effective preventive strategies.
On an individual level, the personal vector protection Prevention of mosquito bites (PPAV) relies primarily on wearing protective clothing, given the small size of the insect vector and its activity from day to night. Conventional skin repellents likely have some activity against the primary vector, although this is difficult to demonstrate experimentally. This primary vector can pass through the mesh of conventional mosquito nets, especially if they are not impregnated.
Therefore, it is recommended:
- to comply with the PPAV measures and in particular the wearing of covering clothing during the day and evening, or even the application of skin repellents, especially during the peak activity of the main vector from 16 to 18 p.m.;
- to avoid unprotected sexual intercourse with people who may have been infected;
- Pregnant women, or women who may become pregnant, should inquire about the epidemiological situation, adopt strict PPAV measures, and reconsider any non-essential travel in the event of a confirmed epidemic.
Travellers to affected areas should be informed of the risks and encouraged to adopt these protective measures, as well as consult travel advice issued by health authorities before departure and upon return.
