Diagnosis of Epizootic Bovine Abortion in Nevada and Identification of the Vector

Hall, Mark R.; Hanks, D.; Kvasnicka, William G.; Bosomworth, A.; Smith, H.; Stott, Jeffrey L; Blanchard, M; Anderson, Margaret Lavinia

doi:10.1177/104063870201400303

Cited by 17 publications

(8 citation statements)

References 8 publications

(9 reference statements)

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“…1,2 The name of the disease is epidemiologically misleading as the disease is endemic, being confined to areas where the transmitting tick, Ornithodoros coriaceus, is present, and possibly, is further confined to locations where the ticks can acquire the agent from a still unidentified intermediate host. The disease is observed in heifers or cows brought into endemic areas for the first time during or after the breeding season.…”

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confidence: 99%

Histochemical and Immunohistochemical Evidence of a Bacterium Associated with Lesions of Epizootic Bovine Abortion

et al. 2006

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Abstract. Epizootic bovine abortion (EBA), a tick-transmitted disease of pregnant cattle grazing foothill pastures, is a major cause of reproductive failure in California and adjacent states. Affected fetuses develop a chronic disease, resulting in late-term abortion or premature calving. Despite investigations spanning 50 years, to the authors' knowledge, the etiologic agent of EBA has not yet been isolated from affected fetuses or the tick vector. The diagnosis of EBA is based on gross and microscopic lesions. Recently, documentation that the etiologic agent is susceptible to antibiotics and identification of a unique 16S deltaproteobacterial rDNA gene sequence in 90% of thymus tissues from aborted fetuses have supported the role of a bacterial infection as the cause of EBA. To determine whether bacteria could be detected in the tissues, histochemical staining and immunohistochemical procedures were used on formalin-fixed, paraffin-embedded tissues. Use of a modified Steiner silver stain revealed small numbers of intracytoplasmic bacterial rods in 37 of 42 thymic samples from EBA-affected fetuses. Improved detection was achieved by use of immunohistochemical staining with serum from EBA-affected fetuses that resulted in detection of numerous bacterial rods in the cytoplasm of histiocytic cells in the thymus from all 42 EBA-affected fetuses. Immunohistochemical examination of additional tissues from 21 field and experimental EBA cases revealed positively stained intracytoplasmic bacterial rods in many organs with inflammatory lesions. Use of the modified Steiner stain and immunohistochemical staining of tissues from negative-control fetuses failed to reveal organisms. To the authors' knowledge, this is the first report to document morphologic evidence of a bacterium associated with the lesions of EBA.

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confidence: 99%

Histochemical and Immunohistochemical Evidence of a Bacterium Associated with Lesions of Epizootic Bovine Abortion

et al. 2006

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“…This habitat type is also where the parajuello tick is found in highest abundance, although nearly 30% (161/549) of the ticks collected were captured in habitats dominated by oak or pine and fir. Epizootic bovine abortion was originally identified as a clinical entity in the southwestern foothills of the Sierra Nevada mountains in California and the disease in cattle and its tick vector is often reported from regions in which juniper species dominate the landscape (Furman & Loomis, 1984; Hall et al , 2002; Chen et al , 2007). The expansion of juniper woodlands into grassland is a recognized phenomenon throughout the western U.S.A. and is often associated with human disturbance and changes in fire ecology in the eastern Sierra Nevada and Great Basin regions (Miller & Rose, 1999; Weisberg et al , 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Susceptible individuals include pregnant heifers or cows that graze in areas infested with O. coriaceus and have not been exposed previously to the bacterial pathogen. The disease, EBA, is widely distributed in the western U.S.A. and is endemic in regions of California (Howarth et al , 1956; Kennedy et al , 1960), Oregon (BonDurant & Anderson, 1997), Idaho and Nevada (Hall et al , 2002). It can be responsible for significant annual production losses and is a common abortigenic pathogen isolated from beef cattle foetuses (Anderson et al , 2006).…”

Section: Introductionmentioning

confidence: 99%

Co-infection of Ornithodoros coriaceus with the relapsing fever spirochete, Borrelia coriaceae, and the agent of epizootic bovine abortion

Teglas

Mapes

Hodzic

et al. 2011

Medical and Veterinary Entomology

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The soft tick, Ornithodoros coriaceus (Koch) (Acari: Argasidae), is a common mammalian parasite of livestock in many arid regions of the western U.S.A. The tick is a known vector of the undescribed bacterial pathogen that causes epizootic bovine abortion (EBA), which results in late-term abortions in beef cattle and subsequent economic loss, which can be considerable, to producers. A second reported bacterial pathogen, Borrelia coriaceae, a member of the relapsing fever complex, has also been identified in this tick and was at one time hypothesized to be the aetiological agent of EBA. In order to test whether bacterial infections in ticks overlapped geographically and to determine the prevalence of co-infection in O. coriaceus populations, we used molecular methods to detect bacterial DNA from ticks collected from a wide variety of habitats in California, Nevada and Oregon. Of the 15 sites at which ticks tested positive for the agent of EBA (aoEBA), eight also contained ticks positive for Borrelia spp. by polymerase chain reaction assay. Additionally, two ticks were co-infected; both of these were collected from the same location. Univariate risk analysis indicated the presence of juniper-dominated habitat at the collection site and geographic location to be significantly associated with infection of the tick vector by either pathogen.

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“…The distribution of the disease is geographically limited to California, Nevada, and Oregon because of the distribution of the only identified vector, Ornithodoros coriaceus (Koch) . A causative agent for EBA had not been identified until relatively recently despite the description of multiple potential pathogens, both bacterial and viral .…”

Section: Introductionmentioning

confidence: 99%

Hematologic and IgG responses of heifers experimentally infected with the agent of epizootic bovine abortion

Coker

Rauw

Nieto

et al. 2012

Veterinary Clinical Pathol

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Background Epizootic bovine abortion (EBA) is a tick‐transmitted abortive disease of beef cattle in the western United States. Infected cattle do not have clinical signs until abortion occurs, usually within the last trimester of gestation. There is little information on the hematologic response of the dam following infection. Objective The purpose of this study was to determine if changes in blood leukocytes and serum IgG concentrations could be detected following experimental infection of pregnant heifers with the etiologic agent of EBA (aoEBA). Methods Twelve Angus heifers were infected during gestation with the aoEBA using an inoculum prepared from the thymus of an infected fetus. Five pregnant heifer controls were given an inoculum prepared from the thymus of an aoEBA‐negative calf. PCVs, total and differential leukocyte counts, and serum IgG concentrations were measured weekly following administration of the inocula until abortion or calving. Gross and microscopic examinations were performed on all aborted fetuses to confirm infection. Results Eleven of 12 heifers in the treatment group aborted, and significant findings were decreased lymphocyte counts at weeks 1 and 14 postinoculation and increased monocyte counts at week 4 compared with control animals. Serum IgG concentrations were significantly increased at weeks 6–8 and 11 in the treatment group. Conclusions Leukogram changes are subtle in infected cattle. Future research efforts should be aimed at development of an antibody test specific for detection of previously infected animals, which could graze safely on EBA‐endemic pastures.

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Diagnosis of Epizootic Bovine Abortion in Nevada and Identification of the Vector

Cited by 17 publications

References 8 publications

Histochemical and Immunohistochemical Evidence of a Bacterium Associated with Lesions of Epizootic Bovine Abortion

Histochemical and Immunohistochemical Evidence of a Bacterium Associated with Lesions of Epizootic Bovine Abortion

Co-infection of Ornithodoros coriaceus with the relapsing fever spirochete, Borrelia coriaceae, and the agent of epizootic bovine abortion

Hematologic and IgG responses of heifers experimentally infected with the agent of epizootic bovine abortion

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