University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Other Publications in Zoonotics and Wildlife Disease Wildlife Disease and Zoonotics 2003 Ehrlichia chaffeensis: a Prototypical Emerging Pathogen Christopher D. Paddock Centers for Disease Control and Prevention, Atlanta James E. Childs Centers for Disease Control and Prevention, Atlanta, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/zoonoticspub Part of the Veterinary Infectious Diseases Commons Paddock, Christopher D. and Childs, James E., "Ehrlichia chaffeensis: a Prototypical Emerging Pathogen" (2003). Other Publications in Zoonotics and Wildlife Disease. 59. https://digitalcommons.unl.edu/zoonoticspub/59 This Article is brought to you for free and open access by the Wildlife Disease and Zoonotics at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Other Publications in Zoonotics and Wildlife Disease by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. CLINICAL MICROBIOLOGY REVIEWS, Jan. 2003, p. 37–64 Vol. 16, No. 1 0893-8512/03/$08.00ϩ0 DOI: 10.1128/CMR.16.1.37–64.2003 Ehrlichia chaffeensis: a Prototypical Emerging Pathogen Christopher D. Paddock* and James E. Childs Viral and Rickettsial Zoonoses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia INTRODUCTION .........................................................................................................................................................38 MICROBIOLOGY ........................................................................................................................................................38 Taxonomy and Phylogenetic Placement.................................................................................................................38 Morphology................................................................................................................................................................39 Isolates of E. chaffeensis ...........................................................................................................................................39 Genetic, Antigenic, and Phenotypic Characteristics ............................................................................................40 PATHOGENESIS..........................................................................................................................................................41 Factors Relating to Disease Severity......................................................................................................................41 Pathology....................................................................................................................................................................41 Immunology ...............................................................................................................................................................44 Entry and Survival of E. chaffeensis in the Cell....................................................................................................45 Animal Models of Disease .......................................................................................................................................45 CLINICAL FEATURES ...............................................................................................................................................46 Characteristics of Disease .......................................................................................................................................46 General clinical features......................................................................................................................................46 Hematologic and biochemical abnormalities ....................................................................................................46 Severe or unusual manifestations ......................................................................................................................46 Dual infections ......................................................................................................................................................47 “Asymptomatic” Infection........................................................................................................................................47 Differential Diagnoses ..............................................................................................................................................47 Comparison with Other Ehrlichioses.....................................................................................................................48 Treatment and Prevention.......................................................................................................................................48 LABORATORY DIAGNOSIS......................................................................................................................................49 Serologic Testing.......................................................................................................................................................49 Indirect immunofluorescence assay....................................................................................................................49 Western blotting....................................................................................................................................................49 Other assays ..........................................................................................................................................................50 Visualization of Morulae and Staining Methods .................................................................................................50 PCR Amplification....................................................................................................................................................50 Isolation......................................................................................................................................................................50 EPIDEMIOLOGY AND ECOLOGY..........................................................................................................................51 Geographic Distribution ..........................................................................................................................................51 United States .........................................................................................................................................................51 Other locations......................................................................................................................................................52 Surveillance for HME ..............................................................................................................................................52 Passive surveillance ..............................................................................................................................................52 Active surveillance ................................................................................................................................................53 Mechanisms of Transmission and Seasonality of Infection ...............................................................................53 Patient Demographics and Risk Factors for HME..............................................................................................53 Tick Vectors ...............................................................................................................................................................53 A. americanum........................................................................................................................................................53 Other tick species .................................................................................................................................................54 Vertebrate Reservoirs...............................................................................................................................................54 White-tailed deer...................................................................................................................................................55 Goats.......................................................................................................................................................................55 Domestic dogs........................................................................................................................................................55 Coyotes ...................................................................................................................................................................55 Other species .........................................................................................................................................................56 Factors Influencing the Emergence of HME ........................................................................................................57 Recent clinical recognition or new disease?......................................................................................................57