Understanding the role of small mammals in the enzootic cycle of Rickettsia parkeri and Amblyomma maculatum in southeastern Virginia

Amblyomma maculatum, the Gulf Coast tick, is a species of increasing public health concern. A. maculatum is the primary vector of Rickettsia parkeri, the causative agent of Rickettsia parkeri rickettsiosis, a form of spotted fever. Amblyomma maculatum has expanded northward from its historic range along the Gulf Coast, with populations reportedly establishing in southeastern Virginia in 2010. Newly established populations of A. maculatum tend to have a higher prevalence of R. parkeri, compared to lower infection rates in the historical range. However, the prevalence of R. parkeri in these populations often decreases over time after the initial establishment period. In Southeastern Virginia, the prevalence of R. parkeri remains high in long established populations of A. maculatum. Little is known about the natural history of A. maculatum in this region, including the predominant hosts of each life stage. Additionally, the factors contributing to the high R. parkeri prevalence in Virginia are unknown. Preliminary work has found native rodent species acting as hosts to immature A. maculatum, with three species likely playing a role in the enzootic cycle of R. parkeri.