Abstract
Oropouche virus is a mosquito-borne viral disease that was previously mainly observed in certain areas of the Americas. Recently, a clear geographic expansion of this virus has been observed, as well as a significant increase in the number of cases reported outside traditional endemic areas.
Epidemiological Standpoint
Geographic Expansion:
Oropouche virus is classified within the Symbovirus group of the genus Orthobunyavirus and has traditionally been confined to the Amazon basin. Currently, there is a worrying expansion of its geographical distribution to include several countries in South America and the Caribbean, such as Brazil, Bolivia, Peru, Colombia, and Cuba, indicating a marked change in its epidemiological pattern.
Update on the Situation:
From the beginning of 2024 until August, more than 8,000 cases of Oropouche virus infection have been confirmed. These cases included two deaths and five cases of vertical transmission (a type of transmission from mother to fetus during pregnancy or childbirth) that have resulted in fetal deaths and birth defects.
In addition, cases have been reported in the United States and Europe among people returning from affected areas in Cuba and Brazil. These cases highlight the need for caution and preventive measures for travelers coming from outbreak areas, especially pregnant women, to reduce the risk of vertical transmission and protect the health of the fetus.
Modes of Transmission:
Oropouche virus is transmitted in forested areas through a natural cycle involving mosquitoes and non-human vertebrate hosts such as sloths, domestic and wild birds, and rodents. Humans visiting these areas can become infected with the virus and then transmit it to urban environments. In cities, infected humans with high levels of the virus in their blood serve as hosts, facilitating the spread of the virus. The primary vectors in urban areas are the fly (Culicoides paraenesis)—found from the northern United States to Argentina—and some mosquitoes (Culex quinquefasciatus), which transmit the virus from an infected person to an uninfected person.
Clinical symptoms:
- The incubation period for Oroposh virus ranges from 3 to 10 days after exposure.
- Clinical symptoms are similar to those of other viral diseases such as dengue fever, Zika virus infection, and chikungunya. They include:
- Fever
- Headache,
- Muscle pain
- Joint pain
- Severe cases may present with hemorrhagic symptoms or neurological complications.
Public Health Response
Strengthening epidemiological surveillance:
Current efforts focus on strengthening surveillance and improving diagnostic capabilities in affected areas. Public health authorities, including the Centers for Disease Control, are validating new diagnostic tests to facilitate rapid and accurate detection.
Preventive strategies:
Since there are no specific vaccines or antiviral treatments for Oroposh virus, preventive strategies focus primarily on vector control and personal protection from insect bites. Also, travelers and pregnant women are advised to exercise extreme caution and avoid travel to high-risk areas.
Clinical Recommendations:
Health care providers call for:
- Maintaining a high level of vigilance for possible infection with the virus in people with symptoms consistent with the disease and a travel history that supports this suspicion.
- Collaborating with local health departments to facilitate timely diagnostic testing.
- Ruling out other viral infections, such as dengue, that share overlapping geographic and clinical features.
- Providing comprehensive counseling to pregnant patients on travel risks and prevention measures.
Conclusion:
- The recent increase in Oropouche virus activity, coupled with its geographic expansion beyond traditional endemic areas, poses significant challenges to public health frameworks.
- Continued vigilance, accurate diagnostic procedures, and effective public health communications are essential to limit the spread of this emerging infectious threat.
- Continued research is needed to better understand the transmission dynamics of the virus and to develop specific treatment and prevention approaches.
References:
- Centers for Disease Control and Prevention (CDC). (2024). Health Alert Network (HAN) Advisory CDCHAN-00515: Increased Oropouche Virus Activity and Associated Risk to Travelers. Distributed via the CDC Health Alert Network, August 16, 2024.
- World Health Organization (WHO). (2023). Oropouche virus – Fact Sheet. [Online]. Available: [WHO website](https://www.who.int)
- Pan American Health Organization (PAHO). (2023). Technical Guidelines for the Prevention and Control of Arboviral Diseases in the Americas.
- National Institutes of Health (NIH). (2023). Oropouche Virus: Emerging Infectious Diseases. Journal of Emerging Infectious Diseases, 23(4), 625-632.
- U.S. Department of Health & Human Services. (2024). Emerging Viral Infections: Guidance for Testing and Reporting. [Online]. Available: [HHS website](https://www.hhs.gov)
- Public Health England. (2024). Guidelines on the Clinical Management of Arboviral Infections. Public Health England Publications.