Oropouche Fever: A Review

Abstract

Oropouche fever is an emerging zoonotic disease caused by Oropouche virus (OROV), an arthropod transmitted Orthobunyavirus circulating in South and Central America. During the last 60 years, more than 30 epidemics and over half a million clinical cases attributed to OROV infection have been reported in Brazil, Peru, Panama, Trinidad and Tobago. OROV fever is considered the second most frequent arboviral febrile disease in Brazil after dengue fever. OROV is transmitted through both urban and sylvatic transmission cycles, with the primary vector in the urban cycle being the anthropophilic biting midge Culicoides paraensis. Currently, there is no evidence of direct human-to-human OROV transmission. OROV fever is usually either undiagnosed due to its mild, self-limited manifestations or misdiagnosed because its clinical characteristics are similar to dengue, chikungunya, Zika and yellow fever, including malaria as well. At present, there is no specific antiviral treatment, and in the absence of a vaccine for effective prophylaxis of human populations in endemic areas, the disease prevention relies solely on vector control strategies and personal protection measures. OROV fever is considered to have the potential to spread across the American continent and under favorable climatic conditions may expand its geographic distribution to other continents. In view of OROV's emergence, increased interest for formerly neglected tropical diseases and within the One Health concept, the existing knowledge and gaps of knowledge on OROV fever are reviewed.

Keywords: Amazon; Culicoides; OROV disease; Oropouche virus; arbovirus.

Figure 1

Schematic diagram of OROV particle and genome structure.

Figure 2

Urban (U) and sylvatic (S) transmission cycles of OROV (Vectors—a: C. paraensis; b: Cx. quinquefasciatus; c: Culicoides midges, Cq. venezuelensis, Ae. serratus, Cx. quinquefasciatus; Hosts—d: birds; e: sloths; f: monkeys).

Figure 3

The spread of OROV in Central and South America from 1955 to 2016 (Bar symbols represent the affected populations in different geographical locations, and the estimated or confirmed number of infected individuals in several outbreaks). 1—Trinidad and Tobago, 1955 first isolated (one case); 2—Belém, Pará, Brazil, 1961 first epidemic (11,000 cases), 1979–1980 epidemic (>100,000 cases); 3—Braganca, Pará, Brazil, 1967 epidemic (6000 cases); 4—Santarém, Pará, Brazil, 1975 epidemic (14,000 cases); 5—Manaus, Amazonas, Brazil, 1980–1981 epidemic (97,000 cases); 6—Panama, 1989 first epidemic (N.D: no data); 7—Ariquemes and Ouro Preto do Oeste, Rondônia, Brazil, 1991 epidemic (94,000 cases); 8—Iquitos, Peru, 1992 first epidemic (five confirmed cases); 9—Magalhães Barata & Maracanã, Pará, Brazil, 2006 epidemic (17,000 cases); 10—Cusco, Peru, 2016 last reported epidemic (61 cases).