Human Monocytotropic Ehrlichiosis

J. E. Dawson; S. A. Ewing; W. R. Davidson; J. E. Childs; S. E. Little; S. M. Standaert

doi:10.1128/9781555816490.ch14

Chapter 14 : Human Monocytotropic Ehrlichiosis

Authors: J. E. Dawson¹, S. A. Ewing², W. R. Davidson³, J. E. Childs⁴, S. E. Little⁵, S. M. Standaert⁶

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Affiliations: 1: Chelan-Douglas Health District, 200 Valley Mall Pkwy., East Wenatchee, WA 98802; 2: 224 Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078; 3: Southeast Cooperative Wildlife Disease Study, College of Veterinary Medicine, University of Georgia, Athens, GA 30602; 4: Department of Biology, 2101 Rollins Basic Science Building, 1510 Clifton Rd. NE, Atlanta, GA 30602; 5: Department of Microbiology and Parasitology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602; 6: 3525 Ensign Rd. NE, Suite 02, Olympia, WA 98506

Content Type: Monograph

Publication Year: 2005

Category: Clinical Microbiology

Book DOI: 10.1128/9781555816490

Chapter DOI: 10.1128/9781555816490.ch14

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Abstract:

This chapter first gives a brief history of human monocytotropic ehrlichiosis (HME), which is a zoonotic disease. From this brief history of HME, it is clear that rapid progress in understanding this newly emerged tick-borne zoonosis was facilitated both by its successful cultivation and by experimental studies of ticks linked to field observations. Epidemiological studies were furthered through the use of molecular techniques, and knowledge of HME expanded rapidly in the early to mid-1990s. Next, the chapter talks about biology of the etiologic agent. In the eastern United States, Ehrlichia chaffeensis is maintained in an epizootic cycle involving the lone star tick (Amblyomma americanum) as the principal vector and the white-tailed deer (Odocoileus virginianus) as a major vertebrate reservoir. This critical vector-host association places these two species at the core of E. chaffeensis epizootiology and strongly influences its geographic distribution and seasonality of transmission. HME caused by E. chaffeensis is endemic to the United States, with residents in the southeastern and south-central states at highest risk. The clinical recognition of HME can be difficult, since the spectrum of manifestations is broad and nonspecific, ranging from asymptomatic infection to mild self-limited symptoms to rapidly fatal disease. HME typically presents as an uncomplicated, acute, nonspecific febrile illness that resolves rapidly if treated with doxycycline, characteristic of many rickettsial infections. The chapter ends with a discussion on laboratory diagnosis, treatment and prevention of HME.

Citation: Dawson J, Ewing S, Davidson W, Childs J, Little S, Standaert S. 2005. Human Monocytotropic Ehrlichiosis, p 239-257. In Goodman J, Dennis D, Sonenshine D, Tick-Borne Diseases of Humans. ASM Press, Washington, DC. doi: 10.1128/9781555816490.ch14

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Human Monocytotropic Ehrlichiosis

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Figure 1

Electron micrograph of E. chaffeensis in the cytoplasm of a macrophage. Photograph appears courtesy of Cynthia Goldsmith (CDC).

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10.1128/9781555816490/fig14-1.gif

Figure 1

Electron micrograph of E. chaffeensis in the cytoplasm of a macrophage. Photograph appears courtesy of Cynthia Goldsmith (CDC).

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Figure 2

Average annual incidence of HME through 2001, as derived from states reporting cases. The legend indicates incidence values stratified into quartiles.

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10.1128/9781555816490/fig14-2.gif

Figure 2

Average annual incidence of HME through 2001, as derived from states reporting cases. The legend indicates incidence values stratified into quartiles.

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Figure 3

(a) The average age-specific incidence of HME derived from states reporting cases; (b) month of onset for HME.

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Figure 3

(a) The average age-specific incidence of HME derived from states reporting cases; (b) month of onset for HME.

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