Oropouche virus (OROV)

Oropouche virus (OROV) is one of the most common arboviruses that infect humans in Brazil (1):

• OROV is the causative agent of Oropouche fever (also known as sloth fever), a febrile arboviral illness that is frequently associated with the Brazilian-Amazon region
  
• an arbovirus of the Orthobunyavirus genus in the Peribunyaviridae family (order Bunyavirales), which is transmitted to humans predominantly by the biting midge Culicoides paraensis (2)
  • transmission of Oropouche virus occurs through both urban and sylvatic cycles, with the anthropophilic biting midge Culicoides paraensis serving as the primary vector in urban areas
  • after being bitten by an OROV-infected midge or mosquito, a 3–8-day incubation period precedes the onset of the disease (3)
    
• OROV is conserved in nature by an urban cycle and a sylvatic cycle, which may include several different vectors:
  • sylvatic cycle
    • in the sylvatic cycle, there is evidence that pale-throated sloths (Bradypus tridactylus), nonhuman primates and some wild birds play a role as vertebrate hosts
  • urban cycle
    • humans are probably also the link between the sylvatic and urban cycles, when humans invade the forest, become infected, and return to urban areas during the viremic period (1)
      • studies have excluded involvement of domestic animals such as cats, dogs or chickens, in the urban cycle, suggesting humans to be the sole vertebrate host, with no evidence of direct human-to-human OROV transmission (2)
• OROV fever is an acute febrile disease, similar to dengue fever, with common clinical symptoms such as fever, headache, muscle and joint pain and skin rash, which may develop into meningitis and/or encephalitis
  • in most individuals, the acute disease is relatively short, lasting from 2 to 7 days, but in some, particularly those with central nervous system involvement (meningitis and encephalitis), the disease can persist for 2–4 weeks and may include asthenia (loss of strength) (3)

Reference:

1. Travassos da Rosa JF, de Souza WM, Pinheiro FP, Figueiredo ML, Cardoso JF, Acrani GO, Nunes MRT. Oropouche Virus: Clinical, Epidemiological, and Molecular Aspects of a Neglected Orthobunyavirus. Am J Trop Med Hyg. 2017 May;96(5):1019-1030.
2. Sakkas H, Bozidis P, Franks A, Papadopoulou C. Oropouche Fever: A Review. Viruses. 2018 Apr 4;10(4):175.
3. Zhang Y, Liu X, Wu Z, Feng S, Lu K, Zhu W, Sun H, Niu G. Oropouche virus: A neglected global arboviral threat. Virus Res. 2024 Mar;341:199318