Epidemiology of Human Ehrlichiosis and Anaplasmosis in the United States, 2001–2002

Demma, Linda J.; Holman, Robert C.; McQuiston, Jennifer H.; Krebs, John W.; Swerdlow, David L.

doi:10.4269/ajtmh.2005.73.400

Cited by 118 publications

(95 citation statements)

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“…Prior infection with several rare and unexpected pathogens was also identified, including the causative agents of anthrax, tularemia, and Q fever. Agents detected at levels similar to those previously reported included T. gondii ), Colorado tick fever virus (McLean et al 1989), E. chaffeensis, and A. phagocytophilum (Yevich et al 1995;Demma et al 2005), though A. phagocytophilum, which was observed in 7% of ROMO participants, is not known to occur in Colorado (Demma et al 2005). While > 7% of participants demonstrated possible prior infection with Brucella spp., these results could not be confirmed due to the potential for cross-reactivity with other bacteria, given the titer levels observed (Al Dahouk et al 2003a, 2003b.…”

Section: Discussionmentioning

confidence: 55%

Zoonotic Infections Among Employees from Great Smoky Mountains and Rocky Mountain National Parks, 2008–2009

Adjemian

Weber

McQuiston

et al. 2012

Vector-Borne and Zoonotic Diseases

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Section: Discussionmentioning

confidence: 55%

Zoonotic Infections Among Employees from Great Smoky Mountains and Rocky Mountain National Parks, 2008–2009

Adjemian

Weber

McQuiston

et al. 2012

Vector-Borne and Zoonotic Diseases

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“…[9][10][11] Patients treated with tetracycline typically recover quickly, and surveillance reports have indicated that the overall case-fatality rate was low. 12,13 Complications can be severe and include adult respiratory distress syndrome, disseminated intravascular coagulopathy, central nervous system involvement, and renal failure. 9,12 Human cases are associated with exposure to ticks.…”

Section: Introductionmentioning

confidence: 99%

“…12,13 Complications can be severe and include adult respiratory distress syndrome, disseminated intravascular coagulopathy, central nervous system involvement, and renal failure. 9,12 Human cases are associated with exposure to ticks. The Lone Star tick, Amblyomma americanum , maintains the enzootic cycle of E. chaffeensis primarily among white-tailed deer ( Odocoileus virginianus ).…”

Section: Introductionmentioning

confidence: 99%

“…16,17,22,23 Previous surveillance summaries found most cases reported within these areas. 12,13 In 2000, the Council of State and Territorial Epidemiologists (CSTE) published surveillance case definitions for infection by E. chaffeensis and A. phagocytophilum . 24 A third reportable category for Undetermined, Unspecified, or Other Agent (UUOA) captured cases where available laboratory evidence was insufficient to specify the causative agent and cases where the causative agent was specified as an agent other than E. chaffeensis or A. phagocytophilum .…”

Section: Introductionmentioning

confidence: 99%

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Increasing Incidence of Ehrlichia chaffeensis and Anaplasma phagocytophilum in the United States, 2000–2007

Dahlgren¹,

Mandel²,

Krebs³

et al. 2011

The American Society of Tropical Medicine and Hygiene

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183

153

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Abstract. Ehrlichia chaffeensis causes human monocytic ehrlichiosis, and Anaplasma phagocytophilum causes human granulocytic anaplasmosis. These related tick-borne rickettsial organisms can cause severe and fatal illness. During 2000-2007, the reported incidence rate of E. chaffeensis increased from 0.80 to 3.0 cases/million persons/year. The case-fatality rate was 1.9%, and the hospitalization rate was 49%. During 2000-2007, the reported incidence of A. phagocytophilum increased from 1.4 to 3.0 cases/million persons/year. The case-fatality rate was 0.6%, and the hospitalization rate was 36%. Rates among female patients were lower than among male patients for ehrlichiosis (rate ratio = 0.68) and anaplasmosis (rate ratio = 0.70). Most (80%) ehrlichiosis and anaplasmosis cases met only a probable case definition, although, use of a polymerase chain reaction to confirm infections increased during [2000][2001][2002][2003][2004][2005][2006][2007]. Heightened reporting of these diseases will likely continue with improving recognition, changing surveillance practices, and appropriate application of diagnostic assays.

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“…Ehrlichia chaffeensis is a gram-negative, obligately intracellular bacterium that causes human monocytic ehrlichiosis, an emerging tick-borne zoonosis (10,23). E. chaffeensis manipulates host monocytes/macrophages throughout its intracellular developmental cycle (25), and this bacterium has a biphasic developmental cycle in mammalian cells that alternates between a small "dense-core cell" (DC) and a large "reticulate cell" (RC), as defined by morphological features, differential surface protein expression, and infectivity (34).…”

mentioning

confidence: 99%

Regulation of Type IV Secretion Apparatus Genes during Ehrlichia chaffeensis Intracellular Development by a Previously Unidentified Protein

2008

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The type IV secretion (T4S) system is critical for the virulence of several pathogens. In the rickettsial pathogen Ehrlichia chaffeensis, the virBD genes are split into two operons, the virB3-virB6 (preceded by sodB) and virB8-virD4 operons. Between these two operons, there are duplications of virB4, virB8, and virB9. In this study we found that transcription of all five loci was downregulated prior to the release of E. chaffeensis from host THP-1 cells and was upregulated at the initiation of exponential growth. Electrophoretic mobility shift assays revealed an E. chaffeensis-encoded protein that specifically bound to the promoter regions upstream of the virBD loci. The protein was purified from the bacterial lysate by affinity chromatography using a biotinylated promoter region upstream of sodB. Mass spectrometry identified the protein as an E. chaffeensis 12.3-kDa hypothetical protein, which was designated EcxR. Recombinant EcxR bound to the promoter regions upstream of five individual virBD loci. EcxR also activated transcription of all five virBD loci in lacZ reporter constructs. The expression of ecxR was positively autoregulated by EcxR. These results suggest that the five virBD loci are coordinately regulated by EcxR to allow developmental stage-specific expression of the T4S system in E. chaffeensis.Ehrlichia chaffeensis is a gram-negative, obligately intracellular bacterium that causes human monocytic ehrlichiosis, an emerging tick-borne zoonosis (10, 23). E. chaffeensis manipulates host monocytes/macrophages throughout its intracellular developmental cycle (25), and this bacterium has a biphasic developmental cycle in mammalian cells that alternates between a small "dense-core cell" (DC) and a large "reticulate cell" (RC), as defined by morphological features, differential surface protein expression, and infectivity (34). The presence of biphasic developmental stages which differ in cell size, infectivity, and the expression of surface protein VirB9 of the type IV secretion (T4S) apparatus has been demonstrated for Anaplasma phagocytophilum, which is closely related to E. chaffeensis (21). The ability to perform the phenotypic switch is likely important for adaptation of the bacterium to harsh extracellular conditions and to initiation of infection, survival, and replication in a new host cell. However, little is known about the mechanisms regulating the developmental cycle of members of the genera Ehrlichia and Anaplasma.Genes encoding the T4S apparatus, the virBD loci, are found in members of the order Rickettsiales, including E. chaffeensis and A. phagocytophilum (17,22). The T4S apparatus of gramnegative bacteria is a transmembrane channel composed of multiple conserved proteins that transport macromolecules across the membrane into eukaryotic target cells in an ATPdependent manner. The T4S system is a critical determinant for virulence in several gram-negative pathogens, such as Agrobacterium tumefaciens, Legionella pneumophila, Helicobacter pylori, and Brucella abortus, because it delivers effec...

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Epidemiology of Human Ehrlichiosis and Anaplasmosis in the United States, 2001–2002

Cited by 118 publications

References 50 publications

Zoonotic Infections Among Employees from Great Smoky Mountains and Rocky Mountain National Parks, 2008–2009

Zoonotic Infections Among Employees from Great Smoky Mountains and Rocky Mountain National Parks, 2008–2009

Increasing Incidence of Ehrlichia chaffeensis and Anaplasma phagocytophilum in the United States, 2000–2007

Regulation of Type IV Secretion Apparatus Genes during Ehrlichia chaffeensis Intracellular Development by a Previously Unidentified Protein

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