203.2 📚 國考版

203.2.0.1 必背 — Classic Rashes Numbering

  • 1st measles, 2nd scarlet fever, 3rd rubella, 5th erythema infectiosum (parvovirus B19), 6th roseola (HHV-6)

203.2.0.2 必背 — Slapped Cheek

  • Children with bright red cheek rash
  • Reticular trunk + extremity rash follows
  • B19 = 5th disease

203.2.0.3 必背 — Receptor

  • P antigen (globoside) on erythrocyte progenitors → tropism

203.2.0.4 必背 — Aplastic Crisis

  • Sickle cell, hereditary spherocytosis, thalassemia + B19 → catastrophic anemia
  • Transfusion + supportive
  • Low reticulocyte

203.2.0.5 必背 — Hydrops Fetalis

  • 1-2 trimester maternal B19 → vertical → fetal erythroid + heart failure
  • MCA Doppler PSV > 1.5 MoM
  • Intrauterine transfusion

203.2.0.6 必背 — Pure Red Cell Aplasia in Immunocompromise

  • HIV, HSCT, transplant
  • Sustained viremia, “lantern cells” in marrow
  • IVIG

203.2.0.7 必背 — Contagious Window

  • Before rash appears (viremic phase)
  • Not contagious once rash visible
  • Implication: schools 通垞 exposure after contagious period