Oropouche Virus Infections on the Rise

Current Situation

As of February 2024, the Pan-American Health Organization (PAHO) has reported an increase in Oropouche virus (OROV) infections across Brazil, Ecuador, French Guiana, Panama, Peru, and Trinidad and Tobago. This surge may be partly attributed to changes in Brazil’s testing and tracking protocols for OROV infections.

Concerns Regarding Pregnancy

A technical note published by Brazil’s Ministry of Health on July 12 raises significant concerns about the impact of OROV during pregnancy. Early indications suggest a connection between the virus and microcephaly in infants who tested positive for Oropouche antibodies, implying potential birth defects.

Understanding Oropouche Fever

History and Symptoms

Since its emergence in the 1950s, Oropouche virus has been prevalent in Latin America and the Caribbean, causing Oropouche fever. The illness shares similarities with yellow fever and dengue, primarily transmitted by mosquitoes and midges. Symptoms include fever, chills, body aches, headaches, and vomiting, with some cases exhibiting hemorrhagic signs or meningitis-like symptoms. Most individuals recover within five to seven days without lasting effects.

Transmission Concerns

Historically, it was believed that OROV transmission occurred solely through insect bites, with no evidence of human-to-human transmission. However, the recent technical note from Brazilian health officials raises alarms about potential vertical transmission, indicating that the virus may be passed from mother to fetus during pregnancy.

Potential Risks of Vertical Transmission

Related Viruses

Other viruses in the simbu virus family, such as Akabane virus (AKAV) and Schmallenberg virus (SBV), can cross the placenta and have caused miscarriages and fetal abnormalities in infected animals. This raises concerns that Oropouche virus may exhibit similar effects. Due to the limited data available, researchers are cautiously advising prospective parents to take preventive measures against insect bites.

Recent Findings

In June 2024, an investigation by Instituto Evandro Chagas discovered traces of OROV in the cerebral spinal fluid or plasma of four children born with microcephaly. Furthermore, a lab probe in July 2024 related to a miscarriage at 30 weeks gestation revealed OROV in umbilical cord blood, placenta, and various fetal organs, suggesting clear evidence of vertical transmission. While a direct link between OROV and fetal abnormalities or miscarriages has yet to be established, health officials advocate for a cautious approach.

Preventive Measures

Travel Warnings

In late June 2024, the U.S. Centers for Disease Control and Prevention (CDC) expressed concerns regarding the spread of Oropouche virus in the Americas, urging travelers to take precautions against mosquito and midge bites.

Recommendations for Travelers

Currently, there is no specific treatment or vaccine for Oropouche fever. Health officials recommend that individuals traveling to affected regions take measures such as using insect repellent, avoiding areas with high concentrations of midges and mosquitoes, utilizing mosquito nets and screens, and covering exposed skin to minimize the risk of infection.

References

Calado AM, Seixas F, Dos Anjos Pires M. Virus as Teratogenic Agents. Methods Mol Biol. 2024;2753:105-142. doi:10.1007/978-1-0716-3625-1_4

Epidemiological Alert – Oropouche in the Region of the Americas – 2 February 2024 – PAHO/WHO | Pan-American Health Organization. Published February 2, 2024. Accessed July 24, 2024. https://www.paho.org/en/documents/epidemiological-alert-oropouche-region-americas-2-february-2024

Oropouche virus disease – French Guiana, France. Accessed July 24, 2024. https://www.who.int/emergencies/disease-outbreak-news/item/oropouche-virus-disease—french-guiana-france

Sakkas H, Bozidis P, Franks A, Papadopoulou C. Oropouche Fever: A Review. Viruses. 2018;10(4):175. doi:10.3390/v10040175

Technical Note No. 15/2024-SVSA/MS — Ministry of Health. Accessed July 24, 2024. https://www.gov.br/saude/pt-br/centrais-de-conteudo/publicacoes/notas-tecnicas/2024/nota-tecnica-no-15-2024-svsa-ms.pdf/view

Wesselmann KM, Postigo-Hidalgo I, Pezzi L, et al. Emergence of Oropouche fever in Latin America: a narrative review. The Lancet Infectious Diseases. 2024;24(7):e439-e452. doi:10.1016/S1473-3099(23)00740-5