Nevada Dividends!

Testing a Vaccine for Epizootic Bovine Abortion (a.k.a. Foothill Abortion)

Issue (Who cares and why?)

Epizootic Bovine Abortion (EBA), commonly known as Foothill Abortion, is one of the major diseases responsible for reducing calf production on ranches in western and northern Nevada, California, southern Idaho and southern Oregon. Although infected pregnant cows do not show visible signs of illness, many of them abort their fetuses at six to nine months of gestation. A significant number of infected cows carry their calves to term, but the calves delivered are weak, fail to thrive and tend to die within the first weeks of independent life.

Following an abortion due to EBA, the effected cow appears to be refractory to subsequent abortion for an undetermined period. This protective immunity appears to wane unless the cows are periodically re-infected by the tick vector. The purpose of this project is to determine the length of time that this immunity remains protective following an EBA induced abortion.

What has been done?

NAES scientists, in collaboration with UC Davis, developed and validated an indirect fluorescent antibody test (iFAT) capable of detecting antibodies specific for the agent of EBA. Sensitivity and specificity were determined by comparing antibody titers from 114 fetuses infected with EBA with 68 fetuses diagnosed with alternate infectious set of causes. Total fetal immunoglobulin (Ig)G was also evaluated as an aid for diagnosing EBA.


The iFAT-based serology assay is rapid, reproducible, and unaffected by fluid color or opacity. Data established specificity at 100% and sensitivity at 94.7% when cutoff criteria for a positive test were assigned at a concentration of greater than 1,000. The presence of immunoglobulin (Ig)G is a sensitive indicator of EBA and increases the specificity of FAT-based serologic diagnosis. Taken together, serology and (Ig)G analyses suggest that the incidence of EBA may be underestimated. Based upon these and other supporting data, the USDA has opened testing to include an addition 2,000 head of cattle from both Nevada and California.

The economic impact from one ranch participating in the vaccine trials (Quinn River Ranch, CA)  has reported that naive heifer reproductive success was almost 100% (66 additional animals), up from a 60% loss prior to vaccination.


Mike Teglas

Department of Agriculture, Veterinary & Rangeland Sciences

1664 North Virginia Street

Reno, Nevada   89557


Phone: (775) 784-1002


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