Kinetics of monocytotropic Ehrlichia infections, new insights from large animal models

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Ehrlichia are tick-borne, obligate intracellular prokaryotic parasites found in host-derived parasitophorous vacuoles. The monocytotropic Erlichia include E. canis and E. chaffeensis. E. canis is the primary causative agent of canine monocytic ehrlichiosis, and E. chaffeensis the primary causative agent of human monocytic ehrlichiosis. To truly understand vector-borne diseases, an understanding of the underlying kinetics between the host, pathogen, and vector are required. Studies described in this dissertation utilize E. canis and E. chaffeensis using large animals models to study host-pathogen kinetics of Ehrlichia, as well as its underlying ecology. E. chaffeensis was demonstrated to be infective to Rhipicephalus Sanguineus ticks acquisition fed on experimentally infected dogs. We also demonstrated, for the first time, natural E. chaffeensis infection of a captive elk from Missouri. E. canis was used in the canine model for further studies defining host-pathogen kinetics. E. canis was shown to produce a cyclic rickettsemia during acute phase CME, and high levels of E. canis infection were detected in tissues of experimentally infected dogs during subclinical canine monocytic ehrlichiosis.