Tick-Borne Illnesses of Alabama: Relationships Among Hosts, Habitats, and Ticks Throughout the State

Abstract

Ticks are the foremost parasites of wildlife and humans in the United States, and may transmit pathogens associated with Lyme disease, Ehrlichiosis, spotted fever Rickettsiosis, and others. Despite the high occurrence of several species of ticks throughout Alabama, little is known about their distribution or the degree to which they carry pathogens. Consequently, the probability of encountering infected ticks in the state is unknown. For this project, we identified land use and climatic factors that affect tick and pathogen distribution and risk, and determined relationships among habitats, ticks, pathogens, and hosts. Ticks were trapped for one year (5/16-5/17) on 105 sites in deciduous, coniferous, pasture, early successional, and residential areas throughout Alabama. Hourly forest floor temperature and relative humidity were recorded on the same sites. Additionally, during the summers of 2015 and 2016, 478 ticks were collected from 89 white-tailed deer in 12 counties, and 3,302 ticks were collected from 809 deer on 12 Wildlife Management Areas during two successive winters from 2015-2017. Preliminary analyses show that across all locations and land uses, minimums and ranges of humidity and temperature are the primary drivers of overall tick abundance, particularly for nymphs. Conversely, within each land use, forest floor characteristics are the primary drivers. Additionally, while only 11% (n=61) of ticks captured on traps are black-legged ticks, 88% (n=2,894) were collected from deer between November to February, elucidating a deer’s critical role in their survival and movement, and suggesting traditional sampling methods for this species are ineffective in the Southeast.