Identification of Oropouche Orthobunyavirus in the cerebrospinal fluid of three patients in the Amazonas, Brazil

Abstract

Oropouche fever is the second most frequent arboviral infection in Brazil, surpassed only by dengue. Oropouche virus (OROV) causes large and explosive outbreaks of acute febrile illness in cities and villages in the Amazon and Central-Plateau regions. Cerebrospinal fluid (CSF) samples from 110 meningoencephalitis patients were analyzed. The RNA extracted from fluid was submitted to reverse transcription-polymerase chain reaction and sequencing to identify OROV. Three CSF samples showed the presence of OROV causing infection in the central nervous system (CNS). These patients are adults. Two of the patients had other diseases affecting CNS and immune systems: neurocysticercosis and acquired immunodeficiency syndrome, respectively. Nucleotide sequence analysis showed that the OROV from the CSF of these patients belonged to genotype I. We show here that severe Oropouche disease is occurring during outbreaks of this virus in Brazil.

Figure 1.

Phylogenetic analysis showing Oropouche virus (OROV) genotypes detected by reverse transcription-polymerase chain reaction (RT-PCR) in cerebrospinal fluids of three patients having meningoencephalitis (bold-italics). This neighbor-joining consensus tree was inferred from 1,000 bootstrap replicates. The percentage of replicate trees, which clustered together in the bootstrap testing, is shown next to the branches. Kimura 2-parameter nucleotide substitution model was chosen as the best-fit after a run on FindModel using all 28 models implemented. (http://www.hiv.lanl.gov/content/sequence/findmodel/findmodel.html). Country and year of isolation is referred between brackets.