Clinical and epidemiological diagnosis of Rio Negro virus

July 27, 2023

go through Wilmer E. Villamil-Gomez, MD MSc FETP Ph.D.

Member of the Scientific Committee of the iO Spain Foundation

Research Group Infectious Diseases and Tropical Diseases Category A Min sciences 2022-2023.Simon Bolivar University of Barranquilla, Colombia

he Heihe virus, an endemic fauna belonging to the Venezuelan equine encephalitis (VEE) complex, corresponding to subtype VI of the serological classification. The viral genome consists of 11.5 KB of positive-strand single-stranded RNA, structural proteins E1, E2, and C are encoded in the 3″ third of the genome, and non-structural proteins (nsP1-4), (Figure 1) contribute to the remaining 2/ 3 5” for encoding. Endemic subtypes of VEE are not virulent in horses, but some subtypes may be pathogenic in humans as ultimate hosts, and in some cases these infections may be fatal. (1)

Figure 1. Rio Negro virus

he climate change This is a very important factor in the re-emergence of this virus, considering it is one of the most urgent and far-reaching environmental and social challenges facing humanity. (2)considering the mechanism of emergence of arboviruses (most arboviruses are zoonotic and maintain an enzootic cycle. Human infection and epidemics may be due to direct random leakage from tangential transmission or when humans come into contact with forest endemics caused by the habitat).

Figure 2. Life cycle

We must consider some useful clinical features of arbovirus infection:

chikungunya fever: Joint long-term pain, swelling, high incidence, popular. Dengue: retro-orbital pain, late petechiae, debilitating myalgia/arthralgia (dengue or Chik -> non-Zika), thrombocytopenia Zika: very mild disease, conjunctivitis. west nile virus (WNV): Epidemiology, actually subcortical encephalitis, most cases -> indistinguishable by clinical presentation alone. (3)

this clinical manifestations Primary care physicians take into account the diagnostic differences of this virus from dengue virus, which is characterized by: Prodrome of fever, headache, photophobia, conjunctivitis, myalgia, arthralgia, nausea and dizziness (1-6 days after infection) , this is where you have to make a differential diagnosis from dengue, (4) Pharyngitis, cervical lymphadenopathy, and lethargy may occur. In rare cases, it can lead to neurological disorders. Symptoms of central nervous system involvement include disorientation, drowsiness, stiff neck, seizures, abnormal ADH secretion, paralysis, coma, and death. Maternal infection can lead to stillbirth or miscarriage. Congenital disorders with malformations of the central nervous system.

We have to keep in mind a series of tests to ensure that diagnosis. With an IV blood count, we can assess for leukopenia and elevated transaminases. Cerebrospinal fluid analysis: increased lymphocytes, elevated protein, elevated glucose ratio. The landscape of the brain is usually normal. EEG: diffuse slowing, mainly temporal focal. IgM detection in serum or cerebrospinal fluid.polymerase chain reaction

treatment and prevention: Treatment is supportive. There are no antiviral drugs available. Mosquito Control Program. surveillance system. Equine Vaccination Program (TC-83; C-84). Quarantine of sick horses.

forecast: Non-neurologic symptoms resolve on their own with full recovery within a few weeks. The overall mortality rate was <1%. Neurologic symptoms occur in 4-14% of children (<1% in adults), with a mortality rate of 20% (higher in children 0-5 years: 35%).

Therefore, ongoing virological clinical surveillance is warranted in Latin America and Europe given the clinical cases of undifferentiated febrile illness.

refer to

  1. Pisano MB, Spinsanti LI, Díaz LA, Farias AA, Almirón WR, Ré VE, Contigiani MS. Rio Negro virus (Venezuelan equine encephalitis complex VI subtype) was first identified in Córdoba, Argentina. Mem Inst Oswaldo Cruz. 2012 Feb;107(1):125-8. DOI: 10.1590/s0074-02762012000100017. PMID: 22310545.
  2. Linares C, Diaz J. Global Sentinel Numbers for the Climate Emergency 1 January 2023
  3. Villamil-Gómez, W. Diagnostic protocols for febrile syndromes involving hematology in geographic areas at risk for endemic tropical infections. drug 13, Issue 58 (June 2022): 3445-54.
  4. Pisano MB, Dantur MJ, Ré VE, Díaz LA, Farias A, Sánchez Seco MP, Tenorio A, Almirón WR, Contigiani MS. Co-circulation of Rio Negro virus (RNV) and Picuna virus (PIXV), Tucumán province, Argentina. Trop Med Int Health. 2010 Jul;15(7):865-8. doi: 10.1111/j.1365-3156.2010.02541.x. Electronic version 17 May 2010. PMID: 20497404

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