Along the Chisholm Trail: Establishing the distribution of lone star tick (Amblyomma americanum) populations in Oklahoma

Amblyomma americanum, the Lone Star tick, has a wide geographic distribution in the United States.  Lone Star ticks are vectors for a wide variety of human and animal pathogens including Ehrlichia spp., Spotted Fever Group Rickettsiae, and Heartland Virus. A recent meta-analysis of the literature highlighted how few counties in Oklahoma have reported established populations of Lone Star ticks, particularly in the western portion of the state.  This reduces effective disease risk assessment in a state with high incidence rates of tick-borne diseases.  Using the Chisholm Trail as a historical marker of the long history of cattle and their ticks in Central Oklahoma, we formed a hypothesis that the ecological and environmental conditions in counties west of the Chisholm Trail would reduce the likelihood of established Lone Star tick populations.  Using CO2 trapping and vegetation flagging, collections were mainly carried out in State Parks, Wildlife Refuges and Wildlife Management Areas.  Lone Star ticks have been collected in 7 counties east of the Trail, 7 counties along the Trail, and 6 counties west of the Chisholm Trail. Ongoing work will test the ticks for Spotted Fever group Rickettsiae and Ehrlichia species using molecular techniques.  Taken together, these data suggest that Lone Star ticks and possibly the disease agents they transmit are much more widespread in Oklahoma than previously described.  This information is of importance to public and veterinary health concerns within Oklahoma as well as the Central United States regarding the potential risks of exposure to tick-borne pathogens.