How Oropouch Fever is Impacting Brazil

Oropouche fever, a disease caused by Oropouche virus has increasingly caused international concern in recent months, drawing attention to emerging infectious diseases and arboviruses. Spread by infected biting midges and occasionally mosquitoes, this disease has primarily occurred in Central and South America, as well as the Caribbean. As more attention has been raised on this viral disease, questions around disease transmission dynamics, symptoms, and public health response continue.¹

According to the Centers for Disease Control and Prevention (CDC) the most common symptoms include fever, severe headache, chills, muscle aches, and joint pain, which tend to last roughly a week.¹ Unfortunately there are no vaccines or treatment modalities for Oropouche beyond supportive care.

Recent reports of viral detection in semen and reports of vertical transmission during pregnancy have prompted further analysis.² The Lancet Infectious Diseases recently published an article on reports of vertical transmission an deaths in Brazil, pointing to the 2015-2016 Zika virus outbreak and importance of enhancing surveillance and interventions.³

The authors emphasized that roughly 5 million people across the Americas are at risk for exposure to the disease and in 2023, there was a significant surge in cases – only 261 cases were reported between 2015-2022, but in 2023 there were 831 and then by August 6, 2024, 7,497 cases were identified. Moreover, two fatalities were confirmed in younger women and in August 2024, the first documented case of vertical transmission was identified, resulting in fetal death.

A second case of vertical transmission was subsequentially found, which also resulted in death of the neonate. The authors noted thatthe neonate was “born with congenital anomalies attributed to vertical transmission—specifically microcephaly, ventriculomegaly, agenesis of corpus callosum, and joint malformations—died after 47 days. The infant's mother had displayed cutaneous eruptions and fever during the second month of gestation, with postpartum virological assessments confirming Oropouche infection.”

As a result of such a steep rise in cases and 2 fetal deaths related to vertical transmission, there is a desperate need for increasing surveillance, education, prevention and control, and further research into clinical progression and related fetal compromise.

The authors pointed to a critical need for community-based interventions, “prevention and control strategies should extend beyond the health-care setting to include the elimination of mosquito breeding sites, the adoption of personal protection measures (particularly among pregnant women, such as the use of repellents, protective clothing, and mosquito nets), and health education initiatives and community mobilization.”

Now is a crucial time in global health, as the US withdraws from the WHO and foreign aid efforts, but it is vital to support ongoing research and interventions against emerging infectious diseases, like Oropouche fever. Learning the lessons from Zika virus, it is imperative we collaborate with partners in the Global South to support additional R&D, public health and healthcare outreach, and identify effective and efficient ways to intervene in Oropouche transmission.

References
1.About Oropouche. CDC.October 11,2024. Accessed January 27, 2025. https://www.cdc.gov/oropouche/about/index.html
2.Castilletti C, Huits R, Mantovani R, et al. Replication-Competent Oropouche Virus in Semen of Traveler Returning to Italy from Cuba, 2024. Emerging Infectious Diseases. 2024;30(12):2684-2686. doi:10.3201/eid3012.241470.
3.Martins-Filho PR, Carvalho TA, Dos Santos CA. Oropouche fever: reports of vertical transmission and deaths in Brazil. Lancet Infect Dis. 2024;24(11):e662-e663. doi:10.1016/S1473-3099(24)00557-7