Ehrlichiosis
Introduction.
Ehrlichiosis is caused by the intracellular parasite Ehrlichia. It is a disease of animals and humans, with an animals reservoir
(deer, fox, coyote etc) (zoonotic).
Transmission occurs through vectors (ticks). Replicating forms = elementary
bodies, form clusters (morulae)
Monocytic Ehrlichiosis
- Cause: Ehrlichia chaffeensis.
- Microscopy: Gram-negative baciili, tiny, intracellular (monocytes):
form morulae
- Transmission: Ticks (vector)
- Symptoms: high fever, headache, malaise, myalgia, leukopenia, late rash
in 30 - 40%
- Complications: mortality of 5%, mostly in immunocompromised &
elderly
- Pathogenesis: Intracellular replication in monocytes; activation of
macrophages
- Treatment: Doxycycline
Granulocytic Ehrlichiosis (Anaplasmosis)
- Cause: Anaplasma phagocyticum
- Microscopy: Gram-negative baciili, tiny, intracellular (WBCs)
- Transmission: Ticks (vector);
small mammals are reservoirs
- Symptoms: high fever, headache, malaise, myalgia, leukopenia, rash
in < 10%
- Complications: mortality of <1%
- Pathogenesis: Intracellular replication in granulocytes, macrophage
activation
- Treatment: Doxycycline