187.2 📚 國考版

187.2.0.1 必背 — HME vs HGA

HME HGA
Pathogen E. chaffeensis A. phagocytophilum
Tick Lone Star (A. americanum) Ixodes (same as Lyme)
Geography SE/SC USA NE/Midwest USA, Europe, Asia
Targeted cell Monocytes Granulocytes (PMN)
Morulae in smear Monocyte (rarely seen) PMN (more visible)
Severity More severe Generally milder

187.2.0.2 必背 — Lab Triad

  • Leukopenia + thrombocytopenia + ↑ LFT
    • hyponatremia common
  • Atypical pneumonia / sepsis with these labs → consider

187.2.0.3 必背 — Treatment

  • Doxycycline 100 bid × 5-7d — all ages, empirical
  • Rifampin alt (pregnancy)
  • Defervescence 24-48 hr = diagnostic

187.2.0.4 必背 — Co-infections (Ixodes Tick)

  • HGA + Lyme + Babesia common
  • Tick-borne disease panel testing

187.2.0.5 必背 — Morulae

  • Pathognomonic intracellular clusters
  • Wright/Giemsa stain peripheral smear
  • HGA in PMN cytoplasm (high sens)