USMLE

Arenavirus

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Viruses - RNA Viruses
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Summary

Arenaviruses are a class of viruses that contain 2 segments of single-stranded RNA. Moreover, their RNA is ambisense, which means that each segment has both positive and negative sense portions. Arenaviruses have a helical capsid that is further surrounded by a viral envelope. LCV, or Lymphocytic Choriomeningitis Virus, is a common arenavirus that can cause meningoencephalitis and is transmitted through exposure to infected hamsters or mice. Lassa Virus is another arenavirus that causes Lassa Fever Encephalitis. Lassa Fever Encephalitis is spread by rodents and transmitted by a high fever, generalized maculopapular rash, and hemorrhaging from the eyes, nose, and mouth. 

Key Points

  • Arenaviruses
    • Characteristics
      • RNA viruses
        • replicate in the cytoplasm of cells
        • Single-stranded
        • + and - sense
        • Circular
        • 2 segments
      • Enveloped
      • Helical capsid
    • Presentation
      • LCV (lymphocytic choriomeningitis virus)
        • Transmission
          • Exposure to infected hamsters or mice (rodents)
          • Does not spread person to person
        • Presentation
          • mild systemic flu-like illness
          • febrile aseptic meningoencephalitis
      • Lassa fever encephalitis
        • Transmission
          • Spread by rodents
          • Endemic in W. Africa
        • Pathogenesis
          • infects dendritic cells/macrophages and disseminates throughout the body
          • replication in endothelial cells causes capillary leak and hemorrhage
        • Presentation
          • Non-specific nausea/vomiting, headache, malaise, diarrhea
          • High fever
          • Generalized maculopapular rash
          • Hemorrhage from eyes, nose, mouth
        • Diagnosis
          • RT-PCR or ELISA (anti-Lassa antibodies) is gold-standard
        • Treatment
          • Supportive care
          • Ribavirin may be used