Natural History of Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) in the Piedmont Physiographic Province of Georgia

Lockhart, J. Mitchell; Davidson, William R.; Stallknecht, David E.; Dawson, Jacqueline E.; Little, Susan E.

doi:10.2307/3284284

Cited by 90 publications

(95 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The nested PCR has been previously used to demonstrate E. chaffeensis DNA in six individual adult A. americanum ticks. 8 Anderson and others demonstrated E. chaffeensis DNA by PCR in one D. variabilis tick that was also positive by direct immunofluorescence for Ehrlichia species. 4 Three A. americanum ticks that were positive by immunofluorescence for Ehrlichia were PCR negative.…”

Section: Discussionmentioning

confidence: 99%

Ehrlichia chaffeensis in Missouri ticks.

Roland¹,

Everett²,

Cyr³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

Abstract. A nested polymerase chain reaction specific for Ehrlichia chaffeensis was used to attempt to amplify DNA from extracts of 100 individual ticks collected from 13 counties in central Missouri. Seventeen of 59 Amblyomma americanum and six of 41 Dermacentor variabilis ticks exhibited the characteristic 389-basepair product. This supports the hypothesis that these tick species may be vectors of human monocytic ehrlichiosis.Human monocytic ehrlichiosis is a nonspecific febrile illness first described in 1987. 1 Based on epidemiologic and polymerase chain reaction (PCR) studies, the etiologic agent, Ehrlichia chaffeensis, is believed to be transmitted predominantly by the Lone Star tick, Amblyomma americanum. 2,3 Missouri is one of the leading states for reported cases of human monocytic ehrlichiosis.The PCR has been used to demonstrate the presence of the 16S rRNA gene sequence of E. chaffeensis in extracts of pooled ticks and in individual ticks. 3,4 The former method used DNA extracted from a pool of ticks to potentially increase target DNA sequences, while the latter was felt to lack sensitivity.A nested PCR greatly enhances sensitivity of detection of target nucleic acid sequences. 5 This method has been used to increase the sensitivity for detection of E. chaffeensis in the blood of white-tailed deer. 6 We now report the results of applying an E. chaffeensis-specific nested PCR technique to 100 individual ticks of the species A. americanum and Dermacentor variabilis collected from 13 counties in Missouri. MATERIALS AND METHODSTicks were collected during the spring and summer of 1995 from 13 different counties in Missouri (Figure 1). Sources of the ticks included vegetation, domestic animals, and humans. The species, sex, and stage of development of each tick were identified by an entomologist; the sex of nymphal ticks could not be determined by visual inspection.DNA was extracted from ticks by a modification of a method previously described. 4 Briefly, individual ticks were placed in 200 l of water, crushed, and boiled for 10 min. This material was diluted 1:2 in 10 mM Tris, pH 8.0, 10 mM NaCl and lysed in the presence of 1.0% sodium dodecyl sulfate and 100 ng of proteinase K/ml for 2 hr at 50ЊC. The lysed suspension was extracted twice with an equal volume of phenol-chloroform. A 1:10 dilution of 3 M sodium acetate, pH 5.5, and a 1:1,000 dilution of 20 mg/ml of glycogen (Boehringer Mannheim, Indianapolis, IN) were added to the extracted aqueous phase. The DNA was precipitated with cold ethanol, washed once with 70% ethanol, dried, and resuspended in 40 l of water.The DNA templates from individual ticks were examined by PCR by a modification of a method previously described. 6 For the initial amplification, 10 l of each template sample was amplified in a 60-l reaction mixture containing the primers ECB (5Ј-CGTATTACCGCGGCTGCTGGCA-3Ј) and EG1 (5Ј-CTCAGAACGAACGCTGGCGG-3Ј) and GeneAmp reagents (Perkin-Elmer Cetus, Norwalk, CT) at concentrations described in the GeneAmp protocol. ECB is part of the primer se...

show abstract

Section: Discussionmentioning

confidence: 99%

Ehrlichia chaffeensis in Missouri ticks.

Roland¹,

Everett²,

Cyr³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

show abstract

“…3,4 Red foxes (Vulpes vulpes) have been shown to be competent hosts for E chaffeensis through experimental infection. 5 Antibodies against E chaffeensis have also been detected in raccoons (Procyon lotor) and opossums (Didelphis virginianus), 6,7 although a role for these species in the natural maintenance cycle of E chaffeensis has not been well established. Ehrlichia chaffeensis and E ewingii are transmitted among reservoir species and to accidental hosts such as humans and dogs by the lone star tick (Amblyomma americanum ; Fig 1), 8,9 which is distributed throughout the southeastern and south-central United States.…”

Section: Pathogen Characteristicsmentioning

confidence: 99%

Ehrlichiosis and related infections

McQuiston

McCall²,

Nicholson³

2003

javma

View full text Add to dashboard Cite

“…9 The utility of C3H/HeJ mice for this purpose is best evaluated based on the results from field samples. Mice inoculated with deer tissue that was PCR positive for E. chaffeensis uniformly failed to seroconvert.…”

Section: Discussionmentioning

confidence: 99%

“…5 However, attempts to culture ticks and blood or other tissues from wild white-tailed deer have encountered problems such as cell culture contamination with exogenous bacteria and trypanosomes (Trypanosoma cervi). 9 Laboratory rodents have been used to study the immunopathology of ehrlichial infections of veterinary medical importance such as E. risiticii. 11,15 Laboratory C3H/HeJ strain mice, which are unable to undergo macrophage activation, 12 were susceptible to infection with E. risticii.…”

mentioning

confidence: 99%

Evaluation of C3H/HeJ Mice for Xenodiagnosis of Infection withEhrlichia Chaffeensis

Lockhart

Davidson

1999

J VET Diagn Invest

Self Cite

View full text Add to dashboard Cite

Abstract. Because mice are experimentally susceptible to infection with Ehrlichia species, C3H/HeJ mice were evaluated as a potential xenodiagnostic model for detection of infection with and isolation of E. chaffeensis. Intraperitoneal inoculation of mice with E. chaffeensis-infected DH82 cell cultures produced seroconversion, with peak serum antibody titers of 1:256, at high dosages (Ͼ1.9 ϫ 10 4 infected cells) but not at low dosages (1.9 or 1.9 ϫ 10 2 infected cells). Ehrlichia chaffeensis was not reisolated from blood samples collected from inoculated mice on postinoculation day 21. Nested polymerase chain reaction (PCR), using primers specific for E. chaffeensis, was positive for only 2/70 (2.9%) tissue samples. A field evaluation in which C3H/HeJ mice were inoculated with blood and lymph node suspensions from 5 seropositive whitetailed deer, including 3 deer that were PCR positive for E. chaffeensis, failed to produce seroconversion in mice. The lack of seroconversion at low dosages, the failure to reisolate at any dosage, and the inability to confirm infection in PCR-positive field samples suggests C3H/HeJ mice are not a sensitive model for xenodiagnosis or detection of E. chaffeensis.Since first described in 1986, more than 400 cases of human monocytic ehrlichiosis have been documented by serologic analysis at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia. 7,8 To date, however, only 3 isolates of the causative agent, Ehrlichia chaffeensis, have been obtained from humans using DH82 canine macrophage cell cultures. 2,3,6 Isolation of E. chaffeensis and related ehrlichae is considered difficult. 1,14 A human isolate of E. chaffeensis has been successfully reisolated from experimentally infected dogs 4 and white-tailed deer (Odocoileus virginianus), the latter being a suspected reservoir host. 5 Researchers reisolated E. chaffeensis 6 times from the blood of 2 deer. 5 However, attempts to culture ticks and blood or other tissues from wild white-tailed deer have encountered problems such as cell culture contamination with exogenous bacteria and trypanosomes (Trypanosoma cervi). 9 Laboratory rodents have been used to study the immunopathology of ehrlichial infections of veterinary medical importance such as E. risiticii. 11,15 Laboratory C3H/HeJ strain mice, which are unable to undergo macrophage activation, 12 were susceptible to infection with E. risticii. In a recent study, 13 C3H/HeJ mice and white-footed deer mice (Peromyscus leucopus), but not LVG strain hamsters or red-backed voles (Cleth- Received for publication February 3, 1998. rionomys gapperi), were susceptible to experimental infection with E. chaffeensis. Because of complications and contaminants associated with performing culture work with wild whitetailed deer, a pilot study was conducted to evaluate C3H/HeJ mice as a xenodiagnostic tool for detection of E. chaffeensis infection. The specific aims of this study were to use serologic, polymerase chain reaction PCR, and cell culture techniques to monitor the response...

show abstract

Natural History of Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) in the Piedmont Physiographic Province of Georgia

Cited by 90 publications

References 6 publications

Ehrlichia chaffeensis in Missouri ticks.

Ehrlichia chaffeensis in Missouri ticks.

Ehrlichiosis and related infections

Evaluation of C3H/HeJ Mice for Xenodiagnosis of Infection withEhrlichia Chaffeensis

Contact Info

Product

Resources

About