La enfermedad por el virus Oropouche (OROV) es una infección febril causada por un arbovirus del género Orthobunyavirus, perteneciente a la familia Peribunyaviridae. Identificado por primera vez en 1955 en Trinidad y Tobago, el OROV ha causado casos y brotes en varios países de América del Sur, incluidos Brasil, Colombia, Ecuador, Guayana Francesa, Panamá, Perú y Venezuela. Los brotes han sido más frecuentes en la región de la Cuenca Amazónica, donde el vector más conocido, el jején (Culicoides paraensis), mantiene un ciclo selvático que involucra a hospedadores como perezosos y primates no humanos.
Los síntomas de la fiebre por Oropouche incluyen fiebre repentina, dolor de cabeza intenso, debilidad extrema (postración), dolores articulares y musculares. En algunos casos, pueden aparecer fotofobia, mareos, náuseas o vómitos persistentes y lumbalgia. La fiebre suele durar hasta cinco días. Aunque las complicaciones graves son poco comunes, la enfermedad puede evolucionar hacia una meningitis aséptica que se manifiesta generalmente en la segunda semana de la enfermedad, lo que prolonga la recuperación por semanas. Se reporta que hasta un 60% de los casos presentan recaídas de los síntomas en las semanas posteriores a la recuperación.
El aumento en la propagación del OROV está vinculado a diversos factores ambientales y humanos. El cambio climático ha intensificado las precipitaciones y temperaturas, mientras que la deforestación y la urbanización han alterado los hábitats naturales de vectores y hospedadores, favoreciendo la interacción entre ellos y aumentando el riesgo de transmisión.
Para controlar la propagación del OROV, se recomienda adoptar medidas de prevención y control de vectores. Esto incluye fortalecer la vigilancia entomológica, reducir las poblaciones de jejenes y educar a la población sobre medidas de protección personal. Entre las recomendaciones específicas destacan el uso de mosquiteros de malla fina en puertas y ventanas, ropa que cubra brazos y piernas, repelentes con DEET o icaridina, y mosquiteros de malla fina sobre las camas o áreas de descanso.
- Desde finales de 2023, se han reportado brotes de la enfermedad por el virus Oropouche en varios países de América del Sur y el Caribe, incluidas áreas sin historial previo de esta enfermedad. Consulte el tablero de casos actualizado.
- De acuerdo a la Evaluación de Riesgos (OPS) a 3 de agosto 2024, en Brasil, se han reportado una muerte fetal y un aborto espontáneo en el estado de Pernambuco, así como cuatro casos de recién nacidos con microcefalia posiblemente vinculados al OROV. Un brote similar ocurrió en Manaus entre 1980 y 1981, con nueve mujeres embarazadas infectadas, de las cuales dos sufrieron abortos espontáneos.
- La confirmación de la enfermedad por Oropouche se realiza mediante pruebas moleculares y serológicas en laboratorios que cuentan con la capacidad adecuada; no existe una prueba rápida disponible.
- No hay tratamiento ni vacuna específica para el Oropouche. El manejo incluye reposo, hidratación y el uso de medicamentos para controlar la fiebre y el dolor, así como el vigilar posibles complicaciones.
- Se han identificado cuatro genotipos del virus Oropouche. La infección con cualquiera de estos genotipos debería inducir la producción de anticuerpos, proporcionando protección frente a reinfecciones futuras.
El virus Oropouche es un virus re-emergente en las Américas, transmitido a las personas principalmente a través de jejenes infectados y algunas especies de mosquitos. Se ha observado que el Oropouche está apareciendo fuera de la Cuenca del Amazonas, en áreas previamente no afectadas.
Además, a Septiembre de 2024 se han registrado hasta el momento dos muertes en personas infectadas en Bahía, Brasil. La infección durante el embarazo se ha relacionado con muerte fetal y posibles defectos congénitos. Asimismo, se encuentran en estudio casos neurológicos (Síndrome de Guillain Barre) posiblemente asociados a la infección por OROV.
Transmisión
El OROV se transmite principalmente a través de la picadura del jején Culicoides paraensis, que habita en áreas boscosas y cerca de cuerpos de agua, y de ciertos mosquitos como Culex quinquefasciatus. Se sospecha que la circulación viral incluye tanto ciclos selváticos como urbanos. En el ciclo selvático, los primates, perezosos y posiblemente algunas aves actúan como huéspedes vertebrados. En el ciclo urbano, los humanos son el huésped amplificador, Se ha documentado transmisión vertical (de madre a hijo) recientemente y se sigue investigando.
Consideraciones adicionales
Se deben realizar estudios de investigación en mujeres embarazadas con posible exposición al virus Oropouche, con el fin de definir mejor el espectro de infecciones congénitas.
Síntomas
Los síntomas son similares a los del dengue y comienzan entre cuatro y ocho días después de la picadura infectante. Los signos incluyen fiebre repentina, dolor de cabeza intenso, debilidad extrema (postración), dolores articulares y musculares, escalofríos, náuseas, diarrea y vómitos persistentes. Aproximadamente el 60% de los casos experimenta recaídas de los síntomas semanas posteriores a la recuperación. Aunque la mayoría se recupera en una semana, algunos pacientes presentan una convalecencia prolongada. Las complicaciones graves, como la meningitis aséptica, son raras, pero pueden aparecer en la segunda semana de la enfermedad.
Tratamiento y vacuna
Actualmente no existe un tratamiento específico ni una vacuna contra el virus Oropouche. El manejo de la enfermedad es de soporte y se enfoca en el alivio de los síntomas, como el reposo, la hidratación y el uso de medicamentos para la fiebre y el dolor, así como vigilar al paciente por la aparición de posibles complicaciones, como, por ejemplo: hipotensión arterial, sudoración intensa que lleva a deshidratación de forma rápida y en especial manifestaciones del sistema nervioso, tales como meningitis, meningoencefalitis y síndrome de Guillain-Barré. En caso de manifestaciones graves, los casos deben ser hospitalizados
Recomendaciones
- Control de vectores: Fortalecer la vigilancia entomológica, reducir las poblaciones de jejenes y mosquitos, y educar a la población sobre medidas de protección personal.
- Medidas de prevención para viajeros: Los viajeros a zonas afectadas deben tomar precauciones contra las picaduras de insectos, usando repelentes con DEET o icaridina, ropa protectora y mosquiteros.
- Recomendaciones para embarazadas: De acuerdo a los Centros de Prevención y Control de Enfermedades de los Estados Unidos (CDC, por sus siglas en inglés), se recomienda a las mujeres embarazadas reconsiderar los viajes no esenciales a áreas con un Aviso de Salud para Viajes de Nivel 2 por el virus Oropouche, debido al riesgo de transmisión materno-fetal.
La OPS/OMS insta a los Estados Miembros a intensificar la vigilancia para la detección oportuna de casos, capacitar al personal de salud en la detección clínica y en el manejo de la enfermedad e informar a la población en riesgo sobre las medidas preventivas.
La OPS/OMS además resalta la importancia del diagnóstico de laboratorio para confirmar los casos y seguir las tendencias de la enfermedad.
Epidemiological UpdatesPublic Health Risk Assessment
Oropouche virus disease (OROV) is a febrile infection caused by an arbovirus of the genus Orthobunyavirus, belonging to the family Peribunyaviridae. First identified in 1955 in Trinidad and Tobago, OROV has caused cases and outbreaks in several South American countries, including Brazil, Colombia, Ecuador, French Guiana, Panama, Peru and Venezuela. Outbreaks have been most frequent in the Amazon Basin region, where the most known vector, the midge (Culicoides paraensis), maintains a sylvatic cycle involving hosts such as sloths and non-human primates.
Symptoms of Oropouche fever include sudden fever, severe headache, extreme weakness (prostration), joint and muscle pain. In some cases, photophobia, dizziness, persistent nausea or vomiting, and low back pain may occur. Fever usually lasts up to five days. Although serious complications are rare, the disease can progress to aseptic meningitis, which usually manifests in the second week of illness, prolonging recovery by weeks. Up to 60% of cases are reported to have relapses of symptoms in the weeks following recovery.
The increased spread of OROV is linked to a variety of environmental and human factors. Climate change has intensified rainfall and temperatures, while deforestation and urbanization have altered the natural habitats of vectors and hosts, favoring interaction between them and increasing the risk of transmission.
To control the spread of OROV, vector prevention and control measures are recommended. This includes strengthening entomological surveillance, reducing midge populations, and educating the population on personal protection measures. Specific recommendations include using fine-mesh mosquito nets on doors and windows, clothing that covers arms and legs, repellents with DEET or icaridin, and fine-mesh nets over beds or sleeping areas.
- Since late 2023, outbreaks of Oropouche virus disease have been reported in several countries in South America and the Caribbean, including areas with no previous history of this disease. Go to the cases and deaths dashboard (in Spanish).
- According to a PAHO Public Health Risk Assessment (August 2024) in Brazil, one fetal death and one miscarriage have been reported in the state of Pernambuco , as well as four cases of newborns with microcephaly possibly linked to OROV. A similar outbreak occurred in Manaus between 1980 and 1981, with nine infected pregnant women, two of whom suffered miscarriages.
- Confirmation of Oropouche disease is done by molecular and serological testing in laboratories with adequate capacity; there is no rapid test available.
- There is no specific treatment or vaccine for Oropouche. Management includes rest, hydration, and the use of medications to control fever and pain, as well as monitoring for possible complications.
- Four genotypes of Oropouche virus have been identified. Infection with any of these genotypes should induce antibody production, providing protection against future reinfection.
Oropouche virus is a re-emerging virus in the Americas, transmitted to people mainly through infected midges and some species of mosquitoes. Oropouche has been observed to be emerging outside the Amazon Basin, in previously unaffected areas.
In addition, as of September 2024, two deaths in infected persons have been reported so far in Bahia, Brazil. Infection during pregnancy has been linked to fetal death and possible birth defects. Neurological cases (Guillain Barre syndrome) possibly associated with OROV infection are also under study.
Transmission
OROV is transmitted mainly through the bite of the midge Culicoides paraensis, which inhabits wooded areas and near bodies of water, and certain mosquitoes such as Culex quinquefasciatus. Viral circulation is suspected to include both sylvatic and urban cycles. In the jungle cycle, primates, sloths and possibly some birds act as vertebrate hosts. In the urban cycle, humans are the amplifying host. Vertical (mother-to-child) transmission has been documented recently and is still under investigation.
Case Definition for Oropouche
Person who presents with acute onset fever (or history of fever) of up to 5 days duration associated with intense headache and two or more of the following manifestations:
- Myalgia or arthralgia
- Chills
- Photophobia
- Dizziness
- Retroocular pain
- Nausea, vomiting or diarrhea (diarrhea is defined as three or more episodes in 24 hours and change in stool consistency)
- Any nervous system manifestation (diplopia, paresthesia, meningitis, encephalitis, meningoencephalitis)
*It is important to note that up to 60% of Oropouche cases may experience a relapse of symptoms between 1 and 10 days after clinical improvement. In cases where Oropouche was not initially suspected, these patients should be reclassified as suspected cases. Given the clinical similarities between Oropouche and dengue, it is essential to conduct a thorough differential diagnosis, ensure close follow-up and monitoring, and assess for warning signs that may indicate dengue rather than Oropouche.
Headache is typically severe and often localized to the posterior (parieto-occipital) region. It commonly persists even after the fever subsides. A severe headache is defined as a pain score of 7 on a 1-to-10 scale. Myalgia and arthralgia are generally diffuse. Unlike chikungunya, arthralgia in Oropouche does not present with inflammatory signs. Patients frequently report neck pain and lower back pain.
Any suspected case that also presents at least one of the following criteria:
- Lives in or has traveled to an area of confirmed transmission of Oropouche cases.
- Has an epidemiological link with a confirmed case of Oropouche.
- Has a positive IgM ELISA test for Oropouche.
Any suspected case that also presents any of the following criteria:
- Has a positive result for the detection of OROV, viral RNA (RT-PCR), or for viral antigens.
- Presents an antibody seroconversion or an increase in antibody titer of at least 4 times in paired samples taken more than 7-10 days apart (and a convalescent sample taken more than 14 days after the onset of symptoms) (25).
- Post-mortem determination of viral RNA by RT-PCR or demonstration of antibodies or antigens by immunohistochemical or other available tests in deceased patients with suspected OROV infection.
- In cases of patients with suspected OROV encephalitis, the result of a positive IgM test in cerebrospinal fluid (CSF) is considered positive.
Case Definition for Vertical Transmission of Oropouche Infection
A. Pregnant women suspected to have Oropouche virus infection +
a. Pregnant women with signs and symptoms consistent with Oropouche infection with exposure in an area with potential circulation (travel or local exposure).
- Recommend to follow the diagnostic testing algorithm.
OR
b. Pregnant women with fetuses with findings of concern on prenatal images.
- Evidence of Central Nervous System defects (such as microcephaly, hydrocephaly) or hydrops.
- Recommend IgM testing of serum (knowing that it is not currently available everywhere)
- Consider RT-PCR testing of amniotic fluid (if appropriate)
B. Fetal or stillbirths suspected to have Oropouche virus infection +
a. Fetal demise/stillbirth in pregnant women with signs and symptoms consistent with Oropouche virus infection.
b. Fetal demise/stillbirth with findings of concerns as evidence of central nervous system defects (such as microcephaly, ventriculomegaly, hydrocephaly) or other associated symptoms (arthrogryposis, macular atrophy), or hydrops.
Recommend testing:
- Fetal tissue, placenta, cord blood, CSF, serum or urine by RT-PCR
- Maternal serum for IgM, urine, and amniotic fluid for viral RNA by RT-PCR
C. Live born infants suspected to have Oropouche virus infection +
a. Livebirths of mothers with laboratory evidence of Oropouche virus infection in pregnancy.
- Recommend RT-PCR on serum and urine, and IgM testing on serum.
OR
b. Livebirths with central nervous system defects such as microcephaly, ventriculomegaly, hydrocephaly or other associated symptoms (arthrogryposis, macular atrophy) or hydrops up to one year of age.
Recommendations
- Clinician suspicion should be heightened for infants with cortical atrophy with minimal to no cortical calcifications and cystic lesions
- Recommend RT-PCR on serum and urine, and IgM testing on serum
- Consider RT-PCR and IgM on CSF (if available)
- Maternal serum should be tested by IgM for serologic evidence of infection if not already testing
- Other infections should be considered and tested for
Additional considerations
Research studies should be conducted of pregnant women with potential exposure to Oropouche virus to better define spectrum of congenital infections.
Symptoms
Symptoms are similar to those of dengue and begin four to eight days after the infecting bite. Signs include sudden fever, severe headache, extreme weakness (prostration), joint and muscle aches, chills, nausea, diarrhea, and persistent vomiting. Approximately 60% of cases experience relapses of symptoms weeks after recovery. Although most recover within a week, some patients have a prolonged convalescence. Serious complications, such as aseptic meningitis, are rare, but may occur in the second week of illness.
Treatment and vaccine
There is currently no specific treatment or vaccine against Oropouche virus. Management of the disease is supportive and focuses on symptom relief, such as rest, hydration and the use of fever and pain medications, as well as monitoring the patient for possible complications, such as arterial hypotension, intense sweating leading to rapid dehydration and especially nervous system manifestations, such as meningitis, meningoencephalitis and Guillain-Barré syndrome. In case of severe manifestations, cases should be hospitalized.
Recommendations
- Vector control: Strengthen entomological surveillance, reduce mosquito and gnat populations, and educate the population on personal protective measures.
- Preventive measures for travelers: Travelers to affected areas should take precautions against insect bites, using repellents with DEET or icaridin, protective clothing and mosquito nets.
- Recommendations for pregnant women: According to the U.S. Centers for Disease Control and Prevention (CDC), pregnant women are advised to reconsider non-essential travel to areas with a Level 2 Travel Health Advisory for Oropouche virus due to the risk of mother-to-child transmission.
PAHO/WHO urges Member States to intensify surveillance for the timely detection of cases, train health personnel in the clinical detection and management of the disease and inform the population at risk about preventive measures. It also stresses the importance of laboratory diagnosis to confirm cases and monitor disease trends.
