Host associations of Dermacentor, Amblyomma, and Ixodes (Acari: Ixodidae) ticks in Tennessee.

From April 2007 to September 2008, 1,793 adult and nymphal ixodid ticks were collected from 49 counties in Tennessee. Six species were identified, including Dermacentor variabilis (Say), Amblyomma americanum (L.), Ixodes texanus (Banks), Ixodes cookei Packard, Ixodes scapularis (Say), and Amblyomma maculatum Koch, from 13 medium- to large-sized mammalian hosts and dragging through vegetation. Raccoons were the most common vertebrate source (198 captures), accounting for 60% of ticks collected. Dermacentor variabilis was the predominant species from raccoons with a prevalence of 92% and mean intensity of 5.3. A. americanum was predominated in white-tailed deer and drags with respective mean intensities of 3.1 and 14.1 and prevalence values of 94%. All tick species were identified between April and August, coinciding with the majority of animal captures. Only A. americanum, I. texanus, and I. cookei were identified from 22 animal captures from November to March. I. texanus and I. cookei were more common in the eastern portions of the state, but this may be a result of higher raccoon captures in those areas. Only four specimens of I. scapularis were collected in this study, which may reflect the absence of small mammal or reptile captures. Two A. maculatum were collected, and we report new distribution records in Tennessee for this species. Despite unequal sampling among ecoregions, the large numbers of D. variabilis and A. americanum from multiple host species suggest their widespread distribution throughout the state. These species of ticks can transmit multiple pathogens, including spotted fever group rickettsiae and ehrlichiae.