Progress 09/01/02 to 08/31/06
Outputs
A variety of different geographical areas in California, Oregon and Nevada, with varying types of vegetation, have been inspected for the presence of Ornithodoros coriaceus, the tick vector of epizootic bovine abortion (EBA). The greatest numbers of ticks have been trapped in juniper and pinion. Minimal ticks have been trapped in evergreen and none in sage. Ticks from all areas and vegetation types have been analyzed for the presence of the bacterial pathogen (agent of EBA, aoEBA) using a polymerase chain reaction (PCR). No apparent associations between the percentage of ticks infected and vegetation type, geographical location and elevation were identified. The percentage of ticks infected with aoEBA from a single geographic site varied between two consecutive years. No data was obtained that would suggest increased numbers of blood meals results in increased frequency of infection. Attempts to increase the percentage of ticks in which aoEBA could be identified by
providing a "clean" blood meal were unsuccessful.
Impacts
Provided extensive information on pathogen/vector/host interactions relative to the bacterial agent that causes foothill abortion (epizootic bovine abortion). Suggested the source of infection for the tick vector is probably not mammalian.
Publications
- Chen CI, KP King, MT Blanchard, MR Hall, BM Aldridge, L Bowen and JL Stott. Identification of the etiologic agent of epizootic bovine abortion in field-collected Ornithodoros coriaceus Koch ticks. Vet Microbiol, 2007, In Press
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Progress 01/01/05 to 12/31/05
Outputs
A variety of different geographical areas in California, Oregon and Nevada, with varying types of vegetation, have been inspected for the presence of Ornithodoros coriaceus, the tick vector of epizootic bovine abortion (EBA). The greatest numbers of ticks have been trapped in juniper and pinion. Minimal ticks have been trapped in evergreen and none in sage. Ticks from all areas and vegetation types have been analyzed for the presence of the bacterial pathogen (agent of EBA, aoEBA) using a polymerase chain reaction (PCR). No apparent associations between the percentage of ticks infected and vegetation type, geographical location and elevation were identified. The percentage of ticks infected with aoEBA from a single geographic site varied between two consecutive years. No data was obtained that would suggest increased numbers of blood meals results in increased frequency of infection. Attempts to increase the percentage of ticks in which aoEBA could be identified by
providing a "clean" blood meal were unsuccessful.
Impacts
Will better define host/vector/pathgoen interactions for epizootic bovine abortion.
Publications
- King, D.P., C-I. Chen, M.T. Blanchard, B.M. Aldridge, M. Anderson, R. Walker, J. Maas, D. Hanks, M. Hall & J.L. Stott. 2005. Molecular identification of a novel deltaproteobacterium as the etiologic agent of epizootic bovine abortion (Foothill abortion). Journal of Clinical Microbiology, 43:604-609.
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Progress 01/01/04 to 12/31/04
Outputs
The project was designed to better define host/vector/pathogen interactions relative to epizootic bovine abortion (EBA). The tick vector of EBA (Ornithidoros coriaceus) was successfully collected in a variety of foothill terrains from Oregon, California and Nevada. A PCR/Southern blotting technique was developed for identification of the etiologic agent of EBA (aoEBA) in the tick vector. The deltaproteobacterial pathogen was identified in ticks from all three states, demonstrating a greater distribution of EBA than is reported in the available literature. The percentage of ticks harborating the EBA agent was highly variable between locations. The agent was identified in nymphs, males and females but not in larvae nor eggs. Current studies are being directed towards analysis of the tick salivary gland as this is the organ that appears to harbor the most bacteria.
Impacts
Will better define host/vector/pathgoen interactions for epizootic bovine abortion.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Epizootic bovine abortion (EBA), or foothill abortion as it is often termed, is considered to be one of the major health problems facing the California and Nevada beef industries. EBA is characterized by late-term abortion or birth of weak calves and is diagnosed pathologically. EBA is caused by a poorly characterized, and as yet uncultured, deltaproteobacteria that is transmitted to susceptible pregnant heifers in foothill regions of California and parts of Nevada and Oregon by the soft-shelled tick, Ornithodoros coriaceus. The tick vector was trapped across an environmental gradient, defined by remote sensing and geographic information system (GIS) data sets, that stretched across the Sierra Nevada mountain range in Nevada and California. Trap sites included both relatively low and high elevations for each of four vegetation types (sage, pinion pine/juniper, evergreen and oak); each vegetation type was further divided into high and low density. Ticks were
successfully captured in sage, pinion pine/juniper and evergreen. The etiologic agent of EBA, a novel deltaproteobacteria, was identified in low percentages of ticks collected in pinion pine/juniper and evergreen. Additional tick trapping is in progress such that sufficient data will be generated to better define the geographical extent of both the vector and pathogen.
Impacts
Will better define host/vector/pathgoen interactions for epizootic bovine abortion.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
Efforts were directed towards completion of a major objective, optomizing identification of O. coriaceus ticks carrying the EBA agent. A PCR/Southern blotting technique was optomized with assay sensitivity being 1 to 5 copies of the etiologic agent's ribosomal gene. Assay specificity was at 100% based upon application of the PCR to 68 bovine fetuses, 42 of which were pathologically diagnosed as being EBA and the remaining being non-EBA abortions or apparently healthy controls. Experiments are in progress to determine if a blood meal will increase the number of ticks in which we can detect the EBA agent. Nymphs, males and females were artifically fed ruminant blood and incubated 45 days prior to sacrifice for PCR analysis. Two groups of control ticks (did not receive a blood meal) were included; one group was sacrificed at the initiation of the experiment and a 2nd group was sacrificed 45 days following initiation of the experiment. Preliminary data suggests the blood
meal did not augment replication of the etiologic agent from undetectable to detectable levels.
Impacts
This project will provide a better understanding of the geographic factors that favor existence of the EBA tick vector, O. coriaceus, and presence of the etiologic agent of EBA. Such information will facilitate implementation of livestock management practices to minimize EBA-associated losses.
Publications
- No publications reported this period
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