Transmission and passage in horses of the agent of human granulocytic ehrlichiosis

J Infect Dis. 1995 Oct;172(4):1141-4. doi: 10.1093/infdis/172.4.1141.


The human granulocytotropic ehrlichia and Ehrlichia equi produce similar diseases in their respective host species (humans, horses). Currently, the phylogenetic and biologic relationships of these 2 uncultured pathogens remain unclear. Previous studies have revealed nucleotide sequence similarity approaching identity at the level of the 16S ribosomal RNA gene. To investigate the biologic similarities of these 2 ehrlichiae, the susceptibility of horses to the human agent was tested by intravenous inoculation of infected human blood. The results demonstrate that the human granulocytotropic ehrlichia produces a disease in the horse indistinguishable from that caused by E. equi, providing biologic evidence that these 2 organisms are highly related and potentially conspecific. It is possible that cases of human illness now attributed to human granulocytotropic ehrlichia may in fact be caused by 1 or more strains of an ehrlichia known chiefly as an equine pathogen.

Publication types

  • Case Reports
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Base Sequence
  • Blood Cell Count
  • DNA, Ribosomal / genetics
  • Ehrlichia / classification*
  • Ehrlichia / genetics
  • Ehrlichia / growth & development
  • Ehrlichiosis / microbiology
  • Ehrlichiosis / transmission
  • Ehrlichiosis / veterinary*
  • Female
  • Fever
  • Granulocytes / microbiology*
  • Granulocytes / pathology
  • Horse Diseases / microbiology*
  • Horses
  • Humans
  • Male
  • Molecular Sequence Data
  • Neutrophils / microbiology
  • Neutrophils / pathology
  • RNA, Ribosomal, 16S / genetics


  • DNA, Ribosomal
  • RNA, Ribosomal, 16S