Emerging Concerns: Oropouche Virus Disease and Its Impact on Public Health

Oropouche virus, primarily transmitted through bites from infected biting midges and, to a lesser extent, mosquitoes, has been a notable concern in the Americas. Recent reports include new cases across South America and the first confirmed case in Cuba as of June 2024. Currently, there is no local transmission in the United States.¹

Oropouche virus typically presents with symptoms such as fever, severe headache, chills, muscle pain, and joint pain. Other symptoms may include photophobia, dizziness, and rash. Symptoms generally appear 3-10 days after infection and last for 2-7 days, though up to 60% of cases can experience a recurrence of symptoms. These symptoms can be similar to those caused by dengue, chikungunya, or Zika viruses, making differential diagnosis challenging.¹

Patients may also exhibit laboratory abnormalities such as lymphopenia, leukopenia, elevated C-reactive protein (CRP) levels, and mild liver enzyme elevations. In rare instances, patients may develop thrombocytopenia or neuroinvasive disease, such as meningitis, with up to 4% of patients experiencing neurologic symptoms. Severe cases may require hospitalization, but fatalities are uncommon. Some patients may experience persistent weakness for up to a month.¹

Recent Alerts and Recommendations

In July 2024, Brazil issued an alert regarding the potential vertical transmission of Oropouche virus, which could lead to adverse pregnancy outcomes such as fetal death or congenital abnormalities. The CDC is working with the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the American Academy of Pediatrics to understand these risks. Pregnant individuals are advised to avoid travel to affected areas and take precautions to prevent insect bites. Also, on August 16, 2024, the CDC issued a Health Advisory about increased Oropouche virus activity and associated risks to travelers.¹

Testing and Reporting

The CDC provides clinical diagnostic testing for Oropouche virus disease through state health departments. Testing involves CLIA-validated molecular assays and neutralizing antibody tests on serum or cerebrospinal fluid (CSF). The suspect case definition includes individuals with recent travel to regions where Oropouche virus circulates and the symptoms. It is important to rule out other diseases, particularly dengue, and to ensure there is no more likely clinical explanation for the symptoms.²

Specimens should be submitted to the CDC according to standard arboviral testing protocols. Available tests include RT-PCR for detecting viral RNA and plaque-reduction neutralization tests (PRNT) for identifying neutralizing antibodies. For pregnant patients, a PRNT result may require confirmation through acute and convalescent serum specimens showing a ≥4-fold change in antibody titers.²

The CDC’s interim guidance for managing Oropouche virus in pregnant individuals is based on recent findings, which suggest that vertical transmission is possible but not well-understood. Cases include a miscarriage at eight weeks gestation and a fetal demise at 30 weeks gestation with Oropouche virus detected in various fetal tissues. Newborns with microcephaly in Brazil have also tested positive for IgM antibodies against Oropouche virus.³

There is no established protocol for fetal ultrasound timing following Oropouche virus infection, but serial ultrasounds (every 4 weeks) are recommended to monitor fetal growth and detect abnormalities that might precede conditions like microcephaly. Consultation with a high-risk prenatal care provider is advised.³

Amniocentesis for detecting Oropouche virus is not currently available, and no specific antiviral treatment or vaccine exists. Coordination with pediatric and infant care providers is essential for pregnancies with suspected fetal abnormalities, and laboratory results should be documented and communicated to ensure thorough newborn evaluation.³

The spread of Oropouche virus, with recent cases in new regions, underscores the need for monitoring, preventive measures, and ongoing research. Public health advisories and updated guidance will continue to play a crucial role in managing and mitigating the impact of this emerging infectious disease.

References

1. Clinical Overview of Oropouche Virus Disease. CDC. September 13, 2024. Accessed September 16, 2024. https://www.cdc.gov/oropouche/hcp/clinical-overview/

2. Updated Interim Guidance for Health Departments on Testing and Reporting for Oropouche Virus Disease. CDC. September 10, 2024. Accessed September 16, 2024. https://www.cdc.gov/oropouche/php/reporting/

3. Updated Interim Guidance for Health Departments on Testing and Reporting for Oropouche Virus Disease. CDC. August 27, 2024. Accessed September 16, 2024. https://www.cdc.gov/oropouche/hcp/clinical-care/pregnancy.html