Viral Exanthems and Herpesviruses

• The most common viral exanthems include chickenpox (varicella), parvovirus (the fifth disease), measles, and rubella (German measles)

Herpesviruses:

• This family includes herpes simplex virus types 1 and 2, which cause painful vesicles on the face and genitals.
• Varicella-zoster virus causes varicella (chickenpox) typically in children.
• Cytomegalovirus is an important cause of congenital malformations.
• Epstein-Barr virus causes infectious mononucleosis.
• Human herpesvirus 8 causes Kaposi's sarcoma.

Varicella-Zoster Virus (VZV):

• This is a DNA enveloped virus, structurally and morphologically similar to other herpesviruses but is antigenically different.
• Varicella (chickenpox) is the primary (usually mild) childhood disease and infection is more serious in adults, potentially prolonged and life-threatening in newborns and individuals with immunodeficiency,
• Zoster (shingles) is usually a disease of adults, especially elderly people, caused by reactivation of latent varicella-zoster virus (VZV).
• In AIDS and other immunocompromised patients zoster is a dreaded disease and is characterised by pain.
• Presents as a rash limited in distribution to the skin

Transmission:

• The virus is transmitted by respiratory droplets and direct contact with the lesions.
• It can be transmitted, usually by direct contact, to children and can cause varicella.
• The appearance of either varicella or zoster in a hospital is a major infection control problem.
• It can be transmitted to immunocompromised patients leading to a life-threatening disseminated infection.

Parvoviruses:

• These are very small (22 nm in diameter) and non-enveloped icosahedral viruses.
• They possess a small linear single-stranded DNA genome and are simple viruses.

Diseases:

• Parvovirus B19 causes "slapped cheeks" syndrome, hydrops fetalis, and severe anemia, especially in those with hereditary anemias such as sickle cell anemia.
• The name "fifth disease" comes from its place on the standard list of rash-causing childhood diseases.

Transmission & Treatment:

• B19 virus is transmitted primarily by the respiratory route; transplacental transmission also occurs
• Humans are the natural reservoir
• There is no specific treatment of B19 infection.
• Regarding Slapped cheek syndrome, the symptoms resolve in about 1 week with no vaccine or chemoprophylaxis available.

Overview of common viral exanthems like chickenpox and measles. Focus on herpesviruses, including varicella-zoster virus (VZV) causing chickenpox and shingles. Discusses the implications of VZV in different age groups and immune statuses.