Detection of<i>Ehrlichia risticii</i>, the Agent of Potomac Horse Fever, in Freshwater Stream Snails (Pleuroceridae:<i>Juga</i>spp.) from Northern California

Barlough, Jeffrey E.; Reubel, G. H.; Madigan, John E.; Vredevoe, Larisa K.; Miller, Paul E.; Rikihisa, Yasuko

doi:10.1128/aem.64.8.2888-2893.1998

Cited by 66 publications

(34 citation statements)

References 36 publications

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“…40 Incomplete protection from vaccination is due in large part to extensive variability in the major surface antigens such as the 51-kDa and 55-kDa major antigens, and there would not be any cross-protection between strains. 21,41 Strain variation is considered an important virulence mechanism in that amino acid sequencing of 51-kDa antigens suggest a geographic segregation of N. risticii strains. 20 In addition, sequence variation has been reported among strains isolated in the early 1980s compared with strains sequenced in the 1990s.…”

Section: Discussionmentioning

confidence: 99%

“…15,16 Vaccine failure has been reported to be as high as 89% and is associated with relatively low levels of vaccine-induced antibodies. 16 Although the epidemiology of EN has been extensively investigated, [17][18][19][20][21][22] and the clinical and clinicopathological changes have been documented in 55 horses that were experimentally infected, 23 there are limited data regarding clinical and clinicopathological aspects of EN in naturally occurring cases. Therefore, the objectives of this retrospective study were to describe the signalment, history (including vaccination status), clinical signs, clinicopathologic values, antimicrobial use, and survival status in horses exhibiting clinical signs of EN, and to identify variables associated with survival.…”

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confidence: 99%

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Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever)

Bertin

Reising

Slovis

et al. 2013

Veterinary Internal Medicne

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Background: The epidemiology of equine neorickettsiosis (EN) has been extensively studied but limited clinical and clinicopathological data are available concerning naturally infected horses.Hypothesis: Factors predictive of survival will be identified in horses diagnosed with EN. Animals: Convenience sample of 44 horses with EN admitted to 2 referral institutions. Methods: A retrospective study was performed. A diagnosis of EN was based on the presence of positive blood or fecal PCR.Results: The most common clinical signs included diarrhea (66%), fever (50%), anorexia (45%), depression (39%), colic (39%), and lameness (18%). The median duration of hospitalization was 6 days and 73% of horses survived to discharge. Laminitis was present in 36% of horses, 88% of which were affected in all 4 feet. Serum creatinine and urea nitrogen concentrations, as well as RBC count, blood hemoglobin concentration, hematocrit, band neutrophils, serum AST activity, serum CK activity, and anion gap, were significantly (P < .05) higher in nonsurvivors. Serum chloride and sodium, concentrations as well as duration of hospitalization were significantly lower in nonsurvivors. The results of forward stepwise logistic regression indicated that blood hemoglobin concentration on admission and antimicrobial treatment with oxytetracycline were independent factors associated with survival.Conclusions and Clinical Importance: Severity of colitis as reflected by electrolyte loss, hemoconcentration, and prerenal azotemia were predictors of survival in horses diagnosed with EN. Treatment with oxytetracycline was associated with increased survival.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever)

Bertin

Reising

Slovis

et al. 2013

Veterinary Internal Medicne

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“…Furthermore, pleurocerids and semisulcospirids do carry Neorickettsia – endosymbionts related to Wolbachia (Fredricks ) – either within their own cells or within the cells of parasitic trematodes (Barlough et al . ; Reubel et al . ; Kanter et al .…”

Section: Discussionmentioning

confidence: 99%

Morphology, molecules and taxonomy: extreme incongruence in pleurocerids (Gastropoda, Cerithioidea, Pleuroceridae)

Whelan

Strong

2015

Zoologica Scripta

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E. (2016). Morphology, molecules and taxonomy: extreme incongruence in pleurocerids (Gastropoda, Cerithioidea, Pleuroceridae). -Zoologica Scripta, 45, 62-87. Pronounced mitochondrial heterogeneity within putative species of Pleuroceridae has prevented meaningful systematic revisions of this critically imperilled freshwater family. Previous studies have demonstrated that this mitochondrial diversity often produces polyphyletic species on mitochondrial gene trees, but its significance is unclear. Hypotheses advanced to explain this pattern have included cryptic species, retained ancestral polymorphisms and introgression; other possible explanations such as doubly uniparental inheritance or the presence of pseudogenes have not been given due consideration. Previous analyses have not included adequate sampling, neither in terms of number of individuals nor in geographic coverage, to adequately test any of these hypotheses. To fully characterize mitochondrial heterogeneity in pleurocerids and robustly assess possible causal explanations, we collected 239 individuals representing four putative species from seven sites and sequenced the COI and 16S rRNA mitochondrial genes and the H3 nuclear gene for all individuals. We also used whole-genome shotgun sequencing to construct and annotate a mitochondrial genome for one individual. Characters with demonstrated utility in morphospecies delineation of gastropods (head-foot coloration, shell and radular morphology, pallial oviduct anatomy) were examined for a subset of individuals to determine whether morphology co-varied by haplotype clade. We found pronounced mitochondrial heterogeneity at both the population level and species level in three of the species examined, but our data reject paralogous nuclear copies of mitochondrial genes (NUMTs) and doubly uniparental inheritance as causal mechanisms, and there was no evidence of cryptic diversity. Mutation rates were found to differ significantly among mitochondrial lineages, and population genetic statistics revealed a signature of balancing selection that could be acting to maintain this diversity. The observed pattern is similar to that seen in lineages with inherited endosymbionts like Wolbachia infections, which merits further investigation. Although questions remain concerning the precise cause(s) of intraspecific mitochondrial diversity in pleurocerids, nuclear and/or genomic data, combined with anatomical and life history investigations in an integrative phylogenetic context, is the most promising avenue for resolving pleurocerid systematics.

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“…39 This molecular assay has contributed to investigation of the epidemiology of PHF, allowing the discovery of helminthic vectors and intermediate and definitive helminthic hosts as well as determining the natural route of infection. [40][41][42][43] NA of N risticii can be detected in the blood and feces of naturally or experimentally infected horses, but the detection time does not necessarily coincide between the 2 sample types (Fig 3). Based on these results, we recommend analyzing both blood and feces from suspected horses in order to enhance the chance of molecular detection of N risticii.…”

Section: Gastrointestinal Pathogensmentioning

confidence: 99%

Real‐Time Polymerase Chain Reaction: A Novel Molecular Diagnostic Tool for Equine Infectious Diseases

Pusterla¹,

Madigan²,

Leutenegger³

2006

Veterinary Internal Medicne

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The focus of rapid diagnosis of infectious disease of horses in the last decade has shifted from the conventional laboratory techniques of antigen detection, microscopy, and culture to molecular diagnosis of infectious agents. Equine practitioners must be able to interpret the use, limitations, and results of molecular diagnostic techniques, as they are increasingly integrated into routine microbiology laboratory protocols. Polymerase chain reaction (PCR) is the best-known and most successfully implemented diagnostic molecular technology to date. It can detect slow-growing, difficult-to-cultivate, or uncultivatable microorganisms and can be used in situations in which clinical microbiology diagnostic procedures are inadequate, time-consuming, difficult, expensive, or hazardous to laboratory staff. Inherent technical limitations of PCR are present, but they are reduced in laboratories that use standardized protocols, conduct rigid validation protocols, and adhere to appropriate quality-control procedures. Improvements in PCR, especially probe-based real-time PCR, have broadened its diagnostic capabilities in clinical infectious diseases to complement and even surpass traditional methods in some situations. Furthermore, real-time PCR is capable of quantitation, allowing discrimination of clinically relevant infections characterized by pathogen replication and high pathogen loads from chronic latent infections. Automation of all components of PCR is now possible, which will decrease the risk of generating false-positive results due to contamination. The novel real-time PCR strategy and clinical applications in equine infectious diseases will be the subject of this review.Key words: Horse; Pathogen detection; TaqMan polymerase chain reaction. Equine practitioners have always considered accurate and rapid identification of infectious pathogens a priority. The ready availability of a correct etiologic diagnosis, particularly in contagious infections, enables the veterinarian to make early decisions on the patient's care and management, address appropriate treatment, and allow timely notification and discussion of management issues regarding prevention of disease spread. The last 2 decades have seen a revolution in the understanding, management, diagnosis, control, and prevention of infectious diseases.1,2 This period has encompassed the discovery of emerging equine agents, antimicrobials, vaccines, as well as a wealth of improved diagnostic tests for equine practitioners. Despite these advances, infectious diseases remain a leading cause of equine morbidity and mortality, with resurgence of certain infections (eg, West Nile virus), an increasing population of elderly, more susceptible horses, and an increasing international equine commerce, expanding the geographic distribution of pathogens. 3,4The focus of rapid diagnosis of infectious diseases also has shifted during this time. The most obvious change has been the appearance and increasing importance of nucleic acid (NA) amplification-based techniques, primarily the...

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Detection ofEhrlichia risticii, the Agent of Potomac Horse Fever, in Freshwater Stream Snails (Pleuroceridae:Jugaspp.) from Northern California

Cited by 66 publications

References 36 publications

Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever)

Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever)

Morphology, molecules and taxonomy: extreme incongruence in pleurocerids (Gastropoda, Cerithioidea, Pleuroceridae)

Real‐Time Polymerase Chain Reaction: A Novel Molecular Diagnostic Tool for Equine Infectious Diseases

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