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Togaviridae

Togaviridae

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    * Togaviruses
– Small – Icosahedral capsids – Outer envelope is derived from the host's plasma membrane. – Arboviruses (arthropod borne viruses) and rubella virus.
Rubivirus genus comprises the rubella virus.
  • Rubella, aka, German measles is transmitted via respiratory droplets.
– Upon inhalation, the virus infects the upper respiratory tractand travels to the lymph nodes. – Viremia disseminates the virus systemically.
  • Infection may be asymptomatic.
  • When present, symptoms are attributed to the formation of immune complexes.
– In children, symptoms are typically mild, and include rash. – In older children and adults, symptoms can be more severe, and include rash and arthralgia.
  • Infection triggers antibody and T-cell responses that clear the virus from the host.
  • Immunity is life-long.
Congenital rubella syndrome aka Gregg Syndrome – "Blueberry muffin lesions" – Cataracts – Serious long-term congenital defects include deafness, blindness, cardiac dysfunction, and developmental impairment.
Vaccine
  • MMR (Measles, Mumps, and Rubella) vaccine prevents rubella infection and congenital defects.
– Recommended for all children.
Alphaviruses
Broadly separated into those that cause encephalitis, and those that cause arthritis.
  • Equine encephalitic viruses include the Eastern, Western, and Venezuelan strains.
  • Infections are often asymptomatic.
  • Mild cases produce flu-like symptoms including fever, chills, and myalgia.
  • More severe cases progress to encephalitis.
  • Arthritic viruses include Sindbis virus (SINV) and Chikungunya viruses.
Although Sindbis virus can cause arthritic symptoms, it is also classified as a member of the Western Equine Encephalitis complex.
  • "Chikungunya" means "to become contorted"
– Its name derives from the bent posture of individuals experiencing arthritic symptoms. – The arthritis may be short lived, but some individuals experience recurrent episodes. – Many individuals experience rash.
Image References
“Chikungunya.” Wikipedia, July 31, 2018. https://en.wikipedia.org/w/index.php?title=Chikungunya&oldid=852854180.
“Eastern Equine Encephalitis.” Wikipedia, July 19, 2018. https://en.wikipedia.org/w/index.php?title=Eastern_equine_encephalitis&oldid=851047709.
“Rubella.” Wikipedia, June 27, 2018. https://en.wikipedia.org/w/index.php?title=Rubella&oldid=847770501.

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