Vaccines may not protect fetus. New vaccines are being developed. Can rid herd of persistently infected cattle. Occurs in cows and heifers pastured on native vegetation in foothill and mountains of California, Oregon, and Nevada. Cows are not sick.
Agent affects the fetus.
Agent apparently spread by soft shelled tick. In soil around trees and in dry brushlands. The tick is spread by deer. Pathogenesis not established. Thought that abortion occurs 3-4 mo.