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• Viral exanthems


  Symmetric, diffuse skin eruptions caused by viral illnesses. Can include macules, papules, pustules, vesicles, wheals or purpura.
• Enanthems


  Oral mucosal eruptions, can include papules, vesicles, erosions, ulcerations or petechiae
• Classification scheme of childhood exanthems

  • 1st disease ~ Measles
  • 2nd disease ~ Scarlet fever
  • 3rd disease ~ Rubella
  • 4th disease ~ Filatov-Dukes ds (an atypical Scarlet fever)
  • 5th disease ~ Erythema infectiosum
  • 6th disease ~ Roseola infantum
• Viral exanthems - Etiologies

  DNA: Erythema infectiosum, exanthem sabitum, Varicella

  RNA: Measles and Rubella
• Viral exanthems - Transmission

  Respiratory droplets/direct contact
• Viral exanthems - Diagnosis


  Advances in viral culture, serology, PCR and EM
• Clues for clinical diagnosis of viral exanthems

  • Primary lesion within the exanthem/Emphasis on skin lesions

  Time of appearance of the eruption against systemic symptoms

  Enanthem

  Distribution of eruptions

  Progression of eruptions (how fast, pattern)

  Other symptoms
• Differential diagnosis of erythematous viral exanthems

  • Measles

  Rubella

  Erythema infectiosum

  Roseola infantum

  CMV

  Infectious Mononucleosis
• Differential diagnosis of vesiculopustular viral exanthems

  • HSV infection

  Varicella & Herpes zoster

  Kaposi's Varicelliform eruption
• Differential diagnosis of purpuric viral exanthems

  • Atypical measles

  Congenital rubella

  Congenital CMV
• Common viral exanthems


  • Measles

  Rubella

  Varicella and Zoster

  Erythema infectiosum

  Roseola infantum
• Measles


  Also known as Rubeola or Morbilli. The greatest killer of children in history.
• Measles epidemiology


  • Affects 50 million people annually globally

  Causes more than 1 million deaths per year

  Higher morbidity and mortality in developing countries

  Over 45% of cases occur before 9 months of age

  Case fatality rate 0.1-0.2% post-vaccine vs 2-10% pre-vaccine
• In Ethiopia from 2002-2003, measles caused 3,797 cases and was the 5th major cause of death in children under 5, accounting for 4% of deaths (around 19,000)
• Measles virus


  Genus Morbillivirus, family Paramyxoviridae, single stranded RNA virus
• Measles transmission


  Respiratory droplets, infected person contagious before rash onset and up to 5 days after rash, attack rate >90-100%
• Measles pathogenesis


  Entry through respiratory tract epithelium

  Replication in regional lymph nodes

  Hematogenous dissemination to skin and mucous membranes

  Viral replication in skin and mucous membranes

  Infection of antigen-presenting cells leading to immunosuppression

  Shift from cell-mediated to humoral immunity
• Measles clinical course


  • Asymptomatic period (10-11 day incubation)

  Prodrome phase (3-4 days, coryza, fever, conjunctivitis, cough)

  Onset of rash (persists 5-6 days, Koplik's spots, systemic signs subside)
• Measles rash


  Begins on 4th febrile day, erythematous macules and papules starting behind ears/forehead, spreads centrifugally and inferiorly, fades in order of appearance over 4-6 days
• Measles systemic signs


  • Generalized lymphadenopathy, nausea/vomiting/diarrhea, splenomegaly, myelitis/encephalitis, secondary infections
• Measles differential diagnosis


  • Drug eruption

  Rubella

  Syphilis

  Leucocytoclastic vasculitis
• Measles diagnosis


  Clinical diagnosis, supported by laboratory tests (cytology, culture, serology, DFA, PCR)
• Measles treatment and prevention

  • Symptomatic treatment (hydration, vitamin A), antibiotics for secondary infections

  MMR vaccine, schedule varies by country (12-15 months, 11-12 years, 3 doses in developing countries)
• Measles prognosis


  Self-limited, mortality rate 10% in poor countries
• Measles complications


  Acute: otitis media, pneumonia, encephalitis, thrombocytopenia, protein-energy malnutrition

  Chronic: subacute sclerosing panencephalitis
• Rubella


  Also known as German measles or three-day measles. Incidence decreased 99% in US since 1969.
• Rubella transmission


  Postnatal: respiratory droplets, Congenital: TORCH infection. Moderately contagious, maximum communicability 2 days before and 5-7 days after rash.
• Rubella pathogenesis


  Respiratory epithelium -> primary viremia -> replication in RES -> secondary viremia -> peripheral blood monocytes -> dissemination
• Rubella clinical features


  • Incubation period 14-21 days

  Characteristic lymphadenopathy (retroauricular, posterior cervical, suboccipital)

  Erythematous, maculopapular rash (1st day face, 2nd day trunk/extremities, 3rd day fades)

  Enanthem (Forchheimer's sign - rose spots/petechiae on soft palate)

  Systemic signs (lymphadenopathy, splenomegaly, arthritis)
• Rubella differential diagnosis


  • Other exanthems

  Drug reactions
• Rubella diagnosis


  Clinical diagnosis, especially during epidemics, supported by serology and viral culture
• Rubella management


  • Symptomatic treatment

  Post-exposure prophylaxis: IV immunoglobulin for non-immune, pregnant women who refuse abortion

  Immunization
• Maximum communicability


  2 days before and 5-7 days after rash
• Up to 40% are asymptomatic
• Rubella pathogenesis


  Respiratory epithelium ⇨ 10 viremia ⇨ replication in RES ⇨ 20 viremia ⇨ peripheral blood monocytes ⇨ entire body [Secretions, CSF, Urine]
• Rubella incubation period


  14 - 21 days
• Rubella characteristic signs


  • Lymphadenopathy: Retroauricular, Posterior cervical and Suboccipital
• Rubella exanthems


  Erythematous, maculopapular rash: 1st day ~ spreads to the face, trunk and extremities, 2nd day ~ facial exanthem fades, 3rd day ~ exanthem fades completely with out residual pigmentary change
• Rubella enanthems


  • Rose colored spots or petechiae on soft palate: Forchheimer's sign
• Rubella systemic signs


  • Lymphadenopathy, Splenomegaly, Arthritis