Oropouche Virus

Current Situation  

As of October 1, 2024, a total of 90 Oropouche (pronounced “o-ro-push”) virus disease cases have been reported from five states among US travelers returning from Cuba. The CDC issued a Health Advisory on August 16, 2024: Increased Oropouche Virus Activity and Associated Risk to Travelers. Currently, there is no evidence of local transmission in the US.  

Overview  

Oropouche virus, a single-stranded negative-sense RNA virus in the genus Orthobunyavirus, is spread to people primarily by the bite of infected biting midges; some mosquitoes can also spread the virus. The virus was first discovered in 1955 and has been reported in parts of South America, Central America, and the Caribbean. In June 2024, Cuba reported its first confirmed Oropouche case. Oropouche virus disease typically presents as an abrupt onset of fever, severe headache, chills, myalgia, and arthralgia. Up to 70% of people with Oropouche virus infection experience recurrence of symptoms within days to weeks of initial resolution of symptoms. The incubation period between exposure and symptoms is thought to be 3-10 days. Oropouche virus infection may be mistaken for infection with other arboviruses such as dengue, chikungunya, and Zika viruses, and malaria.  There are no vaccines to prevent or medicines to treat Oropouche virus infection; prevention relies on personal protective measures to avoid bites. 

Clinical Guidance 

Oropouche virus infection should be considered in a patient who has been in an area with documented or suspected Oropouche virus circulation within 2 weeks of initial symptom onset and who experiences an abrupt onset of fever, headache, and one or more of the following: myalgia, arthralgia, photophobia, retroorbital or eye pain, or signs and symptoms of neuroinvasive disease (eg, stiff neck, altered mental status, seizures, limb weakness, or cerebrospinal fluid pleocytosis).  Because patients with Oropouche virus disease can experience reoccurrence of symptoms after resolution of the initial illness, patients might seek care >2 weeks after travel. 

Clinicians are encouraged to contact their state or local health department if they have a patient with an acute illness and epidemiologic risk factors that might be compatible with Oropouche virus disease. Public health authorities will help determine if samples should be sent to the CDC Arbovirus Diagnostic Laboratory for further testing. Testing for arboviruses with similar clinical symptoms, including dengue, should be performed. 

Patients with suspected Oropouche virus infection should be counseled to avoid taking aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) until dengue can be ruled out to reduce the risk of bleeding. 

People who have recently traveled to an area where Oropouche virus transmission is occurring should be counseled to avoid insect bites for three weeks after travel to prevent spread of the virus to other people via midges or mosquitoes.  

Interim guidance from CDC for evaluating and managing infants born to pregnant people with confirmed or probable Oropouche Virus Disease 

Effect on infants 

The data on congenital Oropouche virus infection are currently limited. In case reports from Brazil, findings among people with Oropouche virus infection during pregnancy have included stillbirth and severe microcephaly. Other viruses that cause congenital infections include Zika virus and cytomegalovirus. Some congenital infections can cause microcephaly, brain anomalies, eye anomalies, hearing loss, and arthrogryposis. The highest risk of Zika-associated birth defects is with first or second trimester infections; however, adverse effects have been reported across all trimesters. It is unclear whether Oropouche virus exposure in utero can cause similar presentations or findings in infants and if the timing of exposure might affect findings. 

Initial evaluation of infants born to people with confirmed or probable Oropouche during pregnancy 

All infants born to people with confirmed or probable Oropouche virus infection during pregnancy should receive a standard evaluation by a healthcare provider at birth and at each well-child visit. A standard evaluation should include: 

• Documentation of the gestational parent’s exposure to and laboratory testing for Oropouche virus in the newborn’s record at delivery 

• A comprehensive newborn physical exam, including: 

• • A complete neurological and joint exam (assessing for arthrogryposis) 

• • A careful measurement of weight, length, and head circumference, with a low threshold to obtain a head ultrasound in the setting of microcephaly or an abnormal neurologic exam 

• • A thorough eye exam with an ophthalmoscope, with a low threshold for ophthalmology referral, especially in the setting of neurologic findings 

• A standard newborn hearing screening at birth, preferably using auditory brainstem response (ABR) method 

• Thorough developmental monitoring, surveillance, and screening as per standard recommendations by the American Academy of Pediatrics 

• Infants with congenital anomalies or other signs suggestive of congenital infection should undergo routine evaluation including testing for other infectious (such as Zika virus, cytomegalovirus, herpes simplex virus, Toxoplasma gondii, etc.) and non-infectious etiologies (such as fetal alcohol spectrum disorder and prenatal methylmercury exposure). 

• Oropouche virus testing by real-time reverse transcription-polymerase chain reaction (rRT-PCR), when available, can be considered in consultation with your state or local health department and CDC (See Testing for Infants below). 

Infants and children with congenital anomalies might benefit from multidisciplinary care including the following specialists: 

• Pediatric Infectious Diseases Specialists 

• Clinical Genetics 

• Pediatric Neurology 

• Pediatric Ophthalmology 

• Developmental Specialists 

Initial evaluation of infants born to people with potential exposure to Oropouche during pregnancy 

For infants born to people who developed a clinically compatible illness while traveling in or within 2 weeks of their return from travel to an area with suspected or confirmed Oropouche virus transmission, the gestational parent (rather than the infant) should be tested for evidence of neutralizing antibodies against Oropouche virus. This testing may be available through state or local health departments or CDC. Testing for non-Oropouche virus infections with overlapping symptoms, such as Zika virus, should be considered as well. If the gestational parent has evidence of infection with Oropouche virus, the infant should undergo an evaluation and testing as described above.  

If the gestational parent did not have symptoms associated with their travel, the infant or their gestational parent should not be tested at this time. 

Testing for infants

Currently, diagnostic testing for Oropouche virus disease is limited. CDC offers a CLIA-validated plaque reduction neutralization test (PRNT) to detect antibodies against Oropouche virus. CDC has a non-CLIA validated Oropouche virus rRT-PCR assay for serum or cerebral spinal fluid (CSF) that is anticipated to be available for diagnostic testing in September 2024. This guidance will be updated as new assays and approved testing on additional specimen types becomes available. 

• PRNT testing: PRNT cannot distinguish between gestational parent and infant antibodies in specimens collected from infants at or near birth. Currently, PRNT testing of infants is not recommended. Rather, PRNT testing should be performed for the gestational parent of affected infants, if not already performed, and results documented within the infant's medical record. 

• rRT-PCR testing: When rRT-PCR is available, infants born to people with confirmed or probable Oropouche during pregnancy should have serum collected as close to birth as possible for rRT-PCR testing. Cord blood should not be used for testing, because cord blood results are associated with both false positives and false negatives for other congenital infections. If CSF is obtained for other purposes, rRT-PCR should also be performed on CSF. Of note, negative rRT-PCR testing does not exclude in utero exposure to Oropouche virus. Given the brief window of rRT-PCR positivity for other similar viruses, virus exposure early in pregnancy may still have occurred, even if molecular testing is negative at birth. Despite this, testing is still recommended, because a positive test might prompt specialist referral if an infant has concerning physical exam findings and can guide future management. 

In cases of fetal or neonatal demise, additional testing might be available. Contact your state or local health department and CDC for additional guidance. 

It is not known if Oropouche virus can be transmitted from person-to-person through bodily fluids. Standard precautions should be practiced when caring for these infants. Currently, infant isolation is not recommended. 

Diagnostic testing is available at some public health laboratories and at CDC. Healthcare providers should consult with their state or local health department regarding testing availability. For current testing and case reporting guidance, please visit the CDC's website (see links below). 

Breastfeeding

At this time, it is unknown if Oropouche virus can be shed or found in breast milk. Because the benefits of breastfeeding outweigh the unknown risk of Oropouche virus spreading through breast milk, CDC continues to encourage breastfeeding, even for those who were infected or lived in or traveled to an area with risk of Oropouche virus infection. 

For Clinical Considerations for Pregnant People: Interim Clinical Considerations for Pregnant People with Confirmed or Probable Oropouche Virus Disease | Oropouche | CDC 

Additional Information on US Cases 

CDC: Oropouche Virus Disease Among U.S. Travelers — United States, 2024 | MMWR (cdc.gov)