Transstadial Transmission and Transovarial Transmission of Ornithodoros coriaceus and Its Connection to Epizootic Bovine Abortion
Agriculture, Nutrition, & Veterinary Science
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Epizootic Bovine Abortion (EBA), also known as Foothill abortion, is a disease of beef cattle in the western U.S. that can result in late term abortion and significant economic losses (McKercher et al., 1963). Ornithodoros coriaceus is the only known vector that transmits the bacteria pathogen (typically referred to as the etiologic agent of EBA, aoEBA) to cattle hosts. The bacteria are a yet unnamed, intracellular organism, genetically most closely related to soil dwelling organisms (King et al., 2005). If an infected tick feeds on a susceptible pregnant cow, the bacterial pathogen can be transmitted to the fetus, where it slowly develops within the fetal calf lymphatic system (Hall et al., 2002). The pregnant cow often develops an asymptomatic infection and does not appear clinically ill while infection in the developing fetus usually results in abortion. In order to determine if Ornithodoros coriaceus can act as a biological vector of aoEBA (as compared to simply serving as a mechanical source of the pathogen), it was tested whether transstadial or transovarial transmission could be detected in experimentally infected ticks. Ticks were collected from an area where the prevalence of the disease was well documented; experimentally infected, fed, and allowed to reproduce. Then through DNA extraction and QPCR ticks were tested for the prevalence of aoEBA. It does not appear that the ticks have a transstadial or transovarial transmission.