Ehrlichia

Allsopp, B. A.; McBride, Jere W.

doi:10.1007/978-3-540-74042-1_4

Cited by 4 publications

(5 citation statements)

References 177 publications

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“…It is evident that E. ruminantium exhibits substantial genetic hetero geneity, and this may have contributed to the inconsistent efficacy of various vaccines for heartwater [42-44]. In fact, eight different 16S rRNA ( rrs ) genotypes are well documented, and there are probably many more [11,45]. Genome sequences have revealed genomic modifications, such as high synonymous substitution rates, truncated genes and plasticity, due to active expansion and contraction of the genome through addition and deletion of tandem repeats (TRs) [41].…”

Section: Genetic and Antigenic Heterogeneitymentioning

confidence: 99%

“…are well described, and understanding the molecular and phenotypic differences that result in such variation can provide needed insight into microbial factors that may contribute to effective vaccines. The best-characterized examples of infectivity and pathogenicity variations are described among E. ruminantium strains in various hosts (e.g., cattle, sheep/goats and mice) [45,78], in which wide variations in pathogenicity are reported. Most recently, nonpathogenic E. ruminantium variants were detected in goats from a heartwater- and Amblyomma -free area, but the variants had genetic markers similar to virulent strains [78].…”

Section: Virulence Factors and Variations In Infectivity And Pathogenicitymentioning

confidence: 99%

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Progress and obstacles in vaccine development for the ehrlichioses

McBride

Walker

2010

Expert Review of Vaccines

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Ehrlichia are tick-borne obligately intracellular bacteria that cause significant diseases in veterinary natural hosts, including livestock and companion animals, and are now considered important zoonotic pathogens in humans. Vaccines are needed for these veterinary and zoonotic human pathogens, but many obstacles exist that have impeded their development. These obstacles include understanding genetic and antigenic variability, influence of the host on the pathogen phenotype and immunogenicity, identification of the ehrlichial antigens that stimulate protective immunity and those that elicit immunopathology, development of animal models that faithfully reflect the immune responses of the hosts and understanding molecular host-pathogen interactions involved in immune evasion or that may be blocked by the host immune response. We review the obstacles and progress in addressing barriers associated with vaccine development to protect livestock, companion animals and humans against these host defense-evasive and cell function-manipulative, vector-transmitted pathogens.

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Section: Genetic and Antigenic Heterogeneitymentioning

confidence: 99%

Section: Virulence Factors and Variations In Infectivity And Pathogenicitymentioning

confidence: 99%

Progress and obstacles in vaccine development for the ehrlichioses

McBride

Walker

2010

Expert Review of Vaccines

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“…In South Africa, a number of studies have been done on tick-borne diseases of canines targeting Ehrlichia canis, Babesia vogeli and Babesia rossi in host animals (Allsopp & McBride 2009 ; Matjila et al 2008 ; McBride et al 1996 ). However, full description of zoonotic pathogens such as Rickettsia species, Borrelia burgdorferi, Anaplasma phagocytophilum and Coxiella burnetii as well as their relationship to emerging and characterised illnesses, is not widely available.…”

Section: Introductionmentioning

confidence: 99%

Occurrence of Coxiella burnetii, Ehrlichia canis, Rickettsia species and Anaplasma phagocytophilum-like bacterium in ticks collected from dogs and cats in South Africa

Mtshali

Sugimoto

Thekisoe

2017

J. S. Afr. Vet. Assoc.

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Ticks are major vectors of arthropod-borne infections and transmit a wide variety of zoonotic pathogens. This study was conducted mainly to determine the occurrence of canine tick-borne bacterial and rickettsial pathogens especially those with zoonotic potential. We examined 276 Rhipicephalus sanguineus, 38 Haemaphysalis elliptica and 4 Amblyomma hebraeum ticks from 90 dogs and 4 cats from the Free State, KwaZulu-Natal, North West and Mpumalanga provinces. DNA of Coxiella burnetii (41%), Ehrlichia or Anaplasma (18%), Rickettsia spp. (37%), Anaplasma phagocytophilum-like bacterium (18%) and Ehrlichia canis (19%) was detected by polymerase chain reaction (PCR) from a total of 147 pooled DNA samples. All samples were negative for the presence of Borrelia burgdorferi DNA. Ehrlichia canis was detected in samples from all the provinces except the North West; A. phagocytophilum was absent in KwaZulu-Natal samples, whereas Rickettsia species and C. burnetii were detected in all sampled provinces. The PCR-positive samples were confirmed by direct sequencing of the product. Data from this study calls for a joint effort by both veterinary and medical sectors to conduct epidemiological studies of the zoonotic pathogens in both animals and humans.

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“…Ehrlichia are Gram-negative obligate intracellular bacteria that exist in nature in a complex lifestyle involving both arthropod vectors and mammalian hosts (All-sopp and McBride 2009). Until recently, the two predominant agents of human ehrlichiosis in the United States were Ehrlichia chaffeensis and Ehrlichia ewingii , which are transmitted by the lone star tick, Amblyomma americanum (Paddock and Yabsley 2007).…”

Section: Introductionmentioning

confidence: 99%

Co-Feeding Transmission of theEhrlichia muris–Like Agent to Mice (Mus musculus)

Karpathy

Allerdice

Sheth

et al. 2016

Vector-Borne and Zoonotic Diseases

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The Ehrlichia muris–like agent (EMLA) is a newly recognized human pathogen found in Wisconsin and Minnesota. Ecological investigations have implicated both the blacklegged tick, Ixodes scapularis, and the white-footed mouse, Peromyscus leucopus, as playing roles in the maintenance of EMLA in nature. The work presented here shows that I. scapularis is an efficient vector of EMLA in a laboratory mouse model, but that Dermacentor variabilis, another frequent human biting tick found in EMLA endemic areas, is not. Additionally, I. scapularis larvae are able to acquire EMLA through co-feeding with infected nymphs. As EMLA only persists in mouse blood for a relatively short period of time, co-feeding transmission may play an important role in the maintenance of EMLA in ticks, and subsequently may play a role in limiting the geographic distribution of this pathogen in areas where co-feeding of larvae and nymphs is less common.

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Ehrlichia

Cited by 4 publications

References 177 publications

Progress and obstacles in vaccine development for the ehrlichioses

Progress and obstacles in vaccine development for the ehrlichioses

Occurrence of <i>Coxiella burnetii</i>, <i>Ehrlichia canis</i>, <i>Rickettsia</i> species and <i>Anaplasma phagocytophilum</i>-like bacterium in ticks collected from dogs and cats in South Africa

Co-Feeding Transmission of theEhrlichia muris–Like Agent to Mice (Mus musculus)

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