Surveillance of Human Ehrlichiosis in the United States: 1988

Eng, Thomas R.; Fishbein, Daniel B.; Dawson, Jacqueline E.; Greene, Cornelia R.; Redus, Martha A.

doi:10.1111/j.1749-6632.1990.tb42237.x

Cited by 9 publications

(6 citation statements)

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“…Further work is needed to determine whether the means of vertebrate host infection can affect tick infection rates. Both A. americanum and D. variabilis acquired all three E. chaffeensis strains, confirming other reports that these species acquire this pathogen in nature (Eng et al, 1990a;Anderson et al, 1993;Ewing et al, 1995;Roland et al, 1998;Kramer et al, 1999).…”

Section: Inoculation Of Calves With Active Cultures Of E Chaffeensissupporting

confidence: 86%

“…Dermacentor variabilis (Bishopp & Tremblet, 1945;Smith et al, 1946;Lancaster, 1973); both A. americanum and D. variabilis are reportedly infected with E. chaffeensis in nature (Eng et al, 1990a;Anderson et al, 1993;Ewing et al, 1995;Roland et al, 1998;Kramer et al, 1999), and thus cattle are likely to be exposed to E. chaffeensis under natural conditions.…”

Section: Introductionmentioning

confidence: 99%

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Experimental infection of dairy calves with Ehrlichia chaffeensis

Santos

Boughan

Bremer

et al. 2007

Journal of Medical Microbiology

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Human monocytic ehrlichiosis (HME) is a zoonotic emerging tick-borne disease with clinical signs that range from mild symptoms to multiple organ failure and death. Ehrlichia chaffeensis, the aetiologic agent of HME, is reported to infect a divergent range of mammals. Although cattle are common hosts of the primary vector of this pathogen, the susceptibility of this host to E. chaffeensis has not been reported to date. This study was undertaken to determine if cattle could provide a useful infection model of E. chaffeensis. Dairy calves were injected with DH82 cells infected with the Arkansas, St Vincent or 91HE17 strain of E. chaffeensis, and monitored for signs of clinical ehrlichiosis and for infection of peripheral blood and ticks by PCR assay. Splenectomized and spleen-intact calves were injected with cryopreserved stabilates of E. chaffeensis-infected DH82 cells for the first experiment. Mild clinical signs were occasionally observed among these calves, and only two blood samples were PCR-positive, while several ticks fed on each calf tested PCR-positive. The second experiment involved injection of normal calves with active cultures of the same E. chaffeensis strains. Interestingly, three of six calves inoculated with active cultures became recumbent and died or had to be euthanized. All of the surviving calves in this experiment tested PCR-positive on multiple dates, but fewer ticks fed on these calves were PCR-positive. These results suggest that a bovine disease model could facilitate the understanding of factors that affect the severity of HME. INTRODUCTIONEhrlichia chaffeensis is an obligate intracellular bacterial parasite and is the aetiologic agent of human monocytic ehrlichiosis (HME), an important emerging tick-borne infectious disease. Clinical outcomes associated with this disease range from asymptomatic to severe and even fatal (Eng et al., 1990b;Everett et al., 1994;Fishbein et al., 1994). E. chaffeensis appears to cause unapparent or mild clinical manifestations in non-primate hosts and this, together with challenges in detecting the pathogen, makes the experimental characterization of E. chaffeensis transmission and pathogenesis difficult. A reliable E. chaffeensis-based animal model of HME would facilitate the understanding of the transmission, pathology and immunology of this malady (Dawson & Ewing, 1992;Dawson et al., 1994;Ewing et al., 1995;Unver et al., 2002;Zhang et al., 2003;Dugan et al., 2004;Loftis et al., 2004).A wide range of mammals are reported to be naturally infected with E. chaffeensis, including white-tailed deer Ewing et al., 1995; Davidson et al., 2001; Varela et al., 2003), domestic goats (Dugan et al., 2000), domestic and wild canids (Dawson et al., 1996;Davidson et al., 1999), and lemurs (Williams et al., 2002 Dermacentor variabilis (Bishopp & Tremblet, 1945;Smith et al., 1946;Lancaster, 1973); both A. americanum and D. variabilis are reportedly infected with E. chaffeensis in nature (Eng et al., 1990a;Anderson et al., 1993;Ewing et al., 1995; Roland et al., 1998; Kram...

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Section: Inoculation Of Calves With Active Cultures Of E Chaffeensissupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Experimental infection of dairy calves with Ehrlichia chaffeensis

Santos

Boughan

Bremer

et al. 2007

Journal of Medical Microbiology

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“…Within the next 5 years, the organism was isolated in cell culture, characterized by molecular techniques, and formally named Ehrlichia chaffeensis (9,73). During this interval, surveillance efforts identified several hundred cases of moderate to severe, and occasionally fatal, ehrlichiosis in patients with unexplained illnesses following tick exposures (97,106,107,125,233,263). These findings indicated that ehrlichiosis was a widespread and significant public health problem of increasing but undefined magnitude.…”

Section: Introductionmentioning

confidence: 94%

Ehrlichia chaffeensis: a Prototypical Emerging Pathogen

2003

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Ehrlichia chaffeensis is an obligately intracellular, tick-transmitted bacterium that is maintained in nature in a cycle involving at least one and perhaps several vertebrate reservoir hosts. The moderate to severe disease caused by E. chaffeensis in humans, first identified in 1986 and reported for more than 1,000 patients through 2000, represents a prototypical “emerging infection.” Knowledge of the biology and natural history of E. chaffeensis, and of the epidemiology, clinical features, and laboratory diagnosis of the zoonotic disease it causes (commonly referred to as human monocytic ehrlichiosis [HME]) has expanded considerably in the period since its discovery. In this review, we summarize briefly the current understanding of the microbiology, pathogenesis, and clinical manifestations associated with this pathogen but focus primarily on discussing various ecological factors responsible for the recent recognition of this important and potentially life-threatening tick-borne disease. Perhaps the most pivotal element in the emergence of HME has been the staggering increases in white-tailed deer populations in the eastern United States during the 20th century. This animal serves as a keystone host for all life stages of the principal tick vector (Amblyomma americanum) and is perhaps the most important vertebrate reservoir host for E. chaffeensis. The contributions of other components, including expansion of susceptible human populations, growth and broadening geographical distributions of other potential reservoir species and A. americanum, and improvements in confirmatory diagnostic methods, are also explored

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“…However, Klein et al reported 75% growth inhibition of A. phagocytophilum with chloramphenicol at 32 g/ml after 3 days (28), and Maurin et al reported variable activity among strains (33). In practice, chloramphenicol is not widely used because of hematological side effects and inconsistent activity (1,11,16,17,19,21). Both chloramphenicol and thiamphenicol inhibit protein synthesis by decreasing peptidyl transferase activity of the 70S ribosome subunit, but chloramphenicol binds to the target site with higher affinity and dramatically decreases polynuclear phagocytic function (10).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Antibiotic Susceptibilities of Ehrlichia canis , Ehrlichia chaffeensis , and Anaplasma phagocytophilum by Real-Time PCR

Branger

Rolain

Raoult

2004

Antimicrob Agents Chemother

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We determined MICs of antibiotics against Anaplasma phagocytophilum, Ehrlichia chaffeensis, and Ehrlichia canis by real-time quantitative PCR. The doubling times of the organisms were established: 19 h for E. chaffeensis, 26 h for A. phagocytophilum, and 28 h for E. canis. In comparison to the reference method for determining sensitivities, which uses Diff-Quick staining, our PCR assay was very sensitive and specific. We confirmed that doxycycline and rifampin are highly active against these bacteria and found variable susceptibilities to fluoroquinolones; A. phagocytophilum was susceptible, but E. canis and E. chaffeensis were only partly susceptible. ␤-Lactam compounds, cotrimoxazole, macrolide compounds, and telithromycin showed no activity against any of the three organisms. Thiamphenicol was found to be more active than chloramphenicol. For the first time, we showed that these three species have numerous point mutations in their 23S RNA genes, with those at positions 754, 2057, 2058, 2059, and 2611 (Escherichia coli numbering) known to confer resistance to macrolide compounds in other bacteria. The role of each of these mutations in resistance to these drugs should be investigated in the future. Our study confirms previous reports that quantitative PCR is a reliable method for determining antibiotic susceptibility; therefore, it might be useful for screening new drugs.

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Surveillance of Human Ehrlichiosis in the United States: 1988

Cited by 9 publications

References 0 publications

Experimental infection of dairy calves with Ehrlichia chaffeensis

Experimental infection of dairy calves with Ehrlichia chaffeensis

Ehrlichia chaffeensis: a Prototypical Emerging Pathogen

Evaluation of Antibiotic Susceptibilities of Ehrlichia canis , Ehrlichia chaffeensis , and Anaplasma phagocytophilum by Real-Time PCR

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