Ehrlichia species is a topic covered in the Johns Hopkins ABX Guide.

To view the entire topic, please or purchase a subscription.

Official website of the Johns Hopkins Antibiotic (ABX), HIV, Diabetes, and Psychiatry Guides, powered by Unbound Medicine. Johns Hopkins Guide App for iOS, iPhone, iPad, and Android included. Explore these free sample topics:

Johns Hopkins Guides

-- The first section of this topic is shown below --

MICROBIOLOGY

  • Cause of tick-borne infection in humans; obligate intracellular pathogens that infect human macrophages and monocytes.
  • Species described as causing human infection:
    • Human monocytic ehrlichiosis (HME): due to Ehrlichia chaffeensis, transmitted by Amblyomma americanum (Lone Star tick, Fig 1) and possibly other tick vectors such as Dermacentor variabilis (American dog tick).
      • Lone star is the most common cause of tick bite in southern U.S. Tick generally in woodland habitats with white-tail deer (thought to be main reservoir).
    • E. ewingii (Ee): canine pathogen that rarely infects humans, infection now termed "human ewingii ehrlichiosis [HEE]."
      • Human cases increasingly described over wider range (10 states), though most to date in Missouri.
    • E. muris: human infection noted in Europe, Russia, Japan/Asia and described in Western U.S. Occurs via tick vector Ixodes persulcatus complex.
    • Ehrlichia species Wisconsin: recently identified[9], close relative of E. muris; likely vector is the Ixodes scapularis tick (same as HGA and B. burgdorferi).
      • Sero-crossreactivity seen with antibodies to E. chaffeensis which may confuse accurate diagnosis.
      • Existing PCR primers for E. chaffeensis and E. ewingii may fail to detect.
      • Usually described as E. muris-like (EML) agent in the literature.
      • Cases to date described in Minnesota and Wisconsin.

-- To view the remaining sections of this topic, please or purchase a subscription --

Last updated: July 31, 2016