Viral Rashes

Varicella (Chicken pox):

• Varicella zoster
• 10-14 day incubation period
• Spreads by direct contact or respiratory route via droplet nuclei
  
• Characterized by the appearance on the skin and mucous membranes of successive crops of typical pruritic vesicular lesions that are easily broken and become scabbed.
  
• Lesions (blisters) start as a 2–4 mm red papule which develops an irregular outline (rose petal). A thin-walled, clear vesicle (dew drop) develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic for chickenpox.
• Highly contagious 2 days before symptoms appear and until all lesions have formed scabs.
• Relatively benign in children; may be complicated by pneumonia and encephalitis in adults.
  

Erythema Infectiosum (Slapped Cheek Syndrome, Fifth Disease):

• Parvovirus B19
• Incubation period 1-3 weeks
• A couple of days before the rash appears, mild flu like symptoms and itching may occur
• A rash and redness may be observed on the cheeks. The rash then spreads to the arms and legs either at the same time or a few days later. In very rare cases the whole body is involved
• Typically children aged 5 to 10 are affected

Measles:

• Caused by a paramyxovirus
• Incubation period 4-12 days
• Highly contagious
• Symptoms include coryza, cough, conjunctivitis and fever
  
• Koplik's spots are pathognomic
  
• Rash is generalized, maculopapular and erythematous, beginning several days after the fever starts. It starts on the head before spreading to cover most of the body. The rash is said to "stain", changing colour from red to dark brown, before disappearing
• Most patients with uncomplicated measles will recover with rest and supportive treatment
• Complications include pneumonia and encephalitis

Rubella (German Measles):

• Rubella virus
• Not related to measles
• 2-3 week incubation period
• Low grade fever, swollen glands, joint pain, headache, conjunctivitis, rash, lymphadenopathy
  
• Pink rash appears on the face (around 3rd day) and then spreads to the trunk and limbs. It disappears after a few days with no staining or peeling of the skin
• If the mother is infected within the first 20 weeks of pregnancy, the child may be born with congenital rubella syndrome (deafness, mental retardation, heart defects)

Roseola infantum (Exanthem subitum and sixth disease):

• Human herpes virus 6
  
• Usually occurs in children between 6 months and 4 years
• Incubation period 10-15 days
  
• High, spiking fever for 2-4 days - without the prodromal symptoms of measles - followed by the onset of a rash
  
• The rash is small, pink, flat, or slightly raised lesions that appear on the trunk and spread to the extremities

Coxsackieviruses (Hand, foot and mouth disease):

• Usually coxsackie A virus
• Incubation period 3-6 days
  
• Affects children under 10 years of age mainly
• Symptoms: fever, rash in mouth, sores/blisters on hands, feet & buttocks, mouth ulcers
• Complications: rarely meningitis, encephalitis, myocarditis, pulmonary oedema