Range Modeling and Surveillance of Ornithodoros turicata Ticks: Implications for Detecting African Swine Fever Virus in the United States.

African Swine Fever virus (ASFv) is a re-emerging global swine disease that, if introduced to the United States, would cause severe economic consequences. The widespread presence of feral hogs in addition to the presence of competent tick vectors, specifically Ornithodoros turicata, fosters a greater risk of ASFv establishment. The specific aims of this study were to assess the geographic distribution of O. turicata, the spatial distribution of host species richness, and to identify localities that could be monitored for ASFv as part of a comprehensive surveillance system in the United States moving forward. A systematic literature review and field collections were conducted to identify O. turicata localities. Ticks were collected from 15/16 surveyed Texas counties and were identified using standard morphological keys and confirmed molecularly on a subset of ticks via amplification and sequencing of a 16S rRNA gene fragment. Ecological niche modeling was used to determine the suite of bioclimatic variables associated with the presence of O. turicata based on field collections and the literature review. Six variables of importance were identified: mean temperature of the warmest quarter, mean temperature of the coldest quarter, annual precipitation, precipitation of the wettest month, precipitation of the warmest quarter, and elevation. Subsequently, a map was constructed of the potential distribution of this species, which stretched from southern California to Texas with an allopatric population in Florida. The majority of Texas, with the exclusion of the easternmost quarter of the state, appears to be highly suitable for this species. Host species richness was greatest in Florida and central Texas, suggesting that these regions should be subjected to targeted surveillance priorities. Furthermore, the presence of O. turicata in burrows occupied by feral common warthogs (Phacochoerus africanus) in south Texas is noteworthy, as warthogs are known to sustain ASFv in a sylvatic cycle in Africa. Establishing the current and projected distribution of O. turicata is essential to understanding the potential sylvatic cycle of ASFv and creating long-term surveillance zones if ASFv is introduced to the United States.