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Microbiology

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Viruses

Togavirus

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Key Points

Togaviruses
- Characteristics
  - RNA viruses
    - replicate in the cytoplasm of cells
    - Single-stranded
  - + sense
  - Linear chromosome
  - Enveloped
  - Icosahedral capsid
- Viruses of Medical importance
  - Chikungunya virus
    - Transmission
      - Arthropod-borne: Aedes mosquito
        Co-infection with Dengue virus can occur
    - Presentation: Chikungunya fever
      - Flu-like illness (fever, nausea/vomiting, myalgias, malaise)
      - Polyarthralgias
      - Diffuse macular rash
  - Rubella virus
    - Transmission
      - Respiratory droplets
        usually affects children
      - Vertical transmission
    - Presentation
      - Rubella
        Also known as German Measles or 3-day Measles
        Fever
        Lymphadenopathy (esp. postauricular)
        Arthralgias
        Maculopapular rash
        Starts on face and spreads downwards to involve trunk and extremities
      - Congenital Rubella
        Sensorineural deafness
        Cataracts
        Cardiac malformations (e.g. PDA)
        Close with indomethacin
        Blueberry muffin appearance
        due to dermal extramedullary hematopoiesis
        Developmental delay may be seen
    - Treatment
      - Supportive
    - Prophylaxis
      - MMR vaccine (Measles, Mumps, Rubella) - live attenuated
        Given at 12-15 months of age
        Has greatly reduced incidence of congenital rubella
  - Eastern and Western Encephalitis