Oropouche virus: Understanding "sloth fever" disease dynamics and novel intervention strategies against this emerging neglected tropical disease

Abstract

Oropouche virus (OROV), an arbovirus belonging to the Orthobunyavirus genus and Peribunyaviridae family, is the causative agent of the so-called "sloth fever." The virus primarily relies on the midge vector Culicoides paraensis for transmission, maintaining both sylvatic and urban cycles. Human infections are characterized by acute febrile symptoms, and severe cases can lead to neurological complications. Since its first isolation in 1955, OROV has caused numerous outbreaks throughout South America, infecting over half a million people. Recent outbreaks in the Amazon and the Caribbean, along with cases reported in U.S. travellers, underscore the growing threat of OROV amid climate change and increased global travel. With no FDA-approved vaccines or specific antiviral treatments available, current management of the disease caused by OROV infection is limited to supportive care. The urgent need for effective vaccines is amplified by the potential for geographic expansion of the virus and its transmitting vector(s). The ongoing development of OROV vaccine candidates represents a crucial step towards controlling future OROV outbreaks and enhancing global public-health preparedness against this emerging infectious disease.

Keywords: OROV; Oropouche virus; acute febrile illness; arbovirus; bunyavirus; sloth fever.

Figure 1.

Transmission dynamics and geographic distribution of oropouche virus (a) transmission cycle of oropouche virus (OROV). The transmission of OROV occurs through sylvatic and urban cycles. After a bite from an infected insect, the incubation period of OROV is 3–8 days. Symptoms generally last for 2–7 days, but in cases of persistent infection, they can extend to 2–4 weeks. If disease recurrence occurs, it typically happens within 10 days of the initial clearance of symptoms. (b) Map of oropouche virus (OROV) outbreaks in 2024 and historic outbreaks in endemic countries in South America. Data reported by the pan American health organization show the number of OROV cases per country as of July 2024. Regions with previous OROV outbreaks without known current cases are highlighted in yellow.