What is HGE & EGE?


Human granulocytic ehrlichiosis (HGE) is an emerging disease of humans caused by a novel, uncharacterized ehrlichia agent.  In 1994 and 1995, this severe, potentially fatal, tick-borne infection was increasingly identified as cause of severe illness in both North American and European areas coinciding with regions endemic for Lyme disease and babesiosis.  Although infrequently diagnosed, the fatality rate approaches 5 % and HGE is prevalent in some areas.  The causative agent of equine granulocytic ehrlichiosis (EGE) is a tick-transmitted disease caused by infection with a Rickettsial agent indistinguishable from Ehrlichia equi.  Infection has been diagnosed in various regions of the United States, British Columbia, Sweden, Switzerland, England and South America.  The newly described HGE and EGE agent has many similarities and may best be considered identical species with variant strains.  Clinical Pathology of EGE: anemia, leukopenia, thrombocytopenia, bilirubin increase, morulae in neutrophils or eosinophils and sero conversion to E. equi antibody by indirect fluorescent antibody test.  Clinical signs and symptoms: HGE in human is generally nonspecific and flu-like; fever, chills, malaise, headache, myalgia, nausea, vomiting, and respiratory distress, EGE in horse may cause fever, lethargy, icterus, limb edema, anorexia, petchiation, and ataxia.

Spirochaeta and Rickettsia Laboratory
Department of Medicine and Epidemiology
School of Veterinary Medicine
University of California
Davis, California 95616-8737
Phone: (530)752-2371, FAX: (530)752-0414
E-mail: ewderock@ucdavis.edu
 Designed by Joon-seok Chae. Send comments and suggestions to: