Ecological epidemiology of bovine babesiosis in south Texas

White-tailed deer and nilgai antelope are the two most abundant free-ranging hoofstock in south Texas. Both species serve as suitable hosts for the cattle ticks Rhipicephalus Boophilus microplus and R. (B.) annulatus hereafter referred to collectively as cattle fever ticks (CFT). During the mid-1900s CFT were eradicated from most of the US, except along the Texas-Mexico border, an area that remains central to the Cattle Fever Tick Eradication Program and designated by the USDA and Texas Animal Health Commission as the Permanent Quarantine Zone (PQZ). Cattle movement within the zone is regulated and tick infestations on cattle are readily addressed and effectively treated, however, natural movement of large wildlife species including white-tailed deer and nilgai antelope within and surrounding the PQZ poses challenges for CFT introduction to tick-free areas. Further, both species readily cross the Rio Grande into Mexico, where CFTs and Babesia bovis, the parasite causing bovine babesiosis, are endemic. An outbreak of bovine babesiosis in TX would devastate the US cattle industry, as the disease can cause up to 90% mortality in the Babesia­-naïve TX beef herd. Our group demonstrated that neither white-tailed deer nor nilgai antelope appear to be susceptible to infection with Babesia bovis and likely do not act to transmit the parasite to uninfected ticks. Ultimately, regardless of the role that wild ungulates have in the transmission of bovine babesiosis, tick control on these alternative hosts remains a critical priority due to their potential to disseminate ticks over long distances.