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  1. Abstract Background

    We conducted a large-scale, passive regional survey of ticks associated with wildlife of the eastern United States. Our primary goals were to better assess the current geographical distribution of exoticHaemaphysalis longicornisand to identify potential wild mammalian and avian host species. However, this large-scale survey also provided valuable information regarding the distribution and host associations for many other important tick species that utilize wildlife as hosts.

    Methods

    Ticks were opportunistically collected by cooperating state and federal wildlife agencies. All ticks were placed in the supplied vials and host information was recorded, including host species, age, sex, examination date, location (at least county and state), and estimated tick burden. All ticks were identified to species using morphology, and suspectH. longicorniswere confirmed through molecular techniques.

    Results

    In total, 1940 hosts were examined from across 369 counties from 23 states in the eastern USA. From these submissions, 20,626 ticks were collected and identified belonging to 11 different species. Our passive surveillance efforts detected exoticH. longicornisfrom nine host species from eight states. Notably, some of the earliest detections ofH. longicornisin the USA were collected from wildlife through this passive surveillance network. In addition, numerous new county reports were generated forAmblyomma americanum,Amblyomma maculatum,Dermacentor albipictus,Dermacentor variabilis, andIxodes scapularis.

    Conclusions

    This study provided data on ticks collected from animals from 23 different states in the eastern USA between 2010 and 2021, with the primary goal of better characterizing the distribution and host associations of the exotic tickH. longicornis;however, new distribution data on tick species of veterinary or medical importance were also obtained. Collectively, our passive surveillance has detected numerous new county reports forH. longicornisas well asI. scapularis.Our study utilizing passive wildlife surveillance for ticks across the eastern USA is an effective method for surveying a diversity of wildlife host species, allowing us to better collect data on current tick distributions relevant to human and animal health.

     
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  2. Abstract

    The blacklegged tick (Ixodes scapularis(Journal of the Academy of Natural Sciences of Philadelphia, 1821,2, 59)) is a vector ofBorrelia burgdorferisensu stricto (s.s.) (International Journal of Systematic Bacteriology, 1984,34, 496), the causative bacterial agent of Lyme disease, part of a slow‐moving epidemic of Lyme borreliosis spreading across the northern hemisphere. Well‐known geographical differences in the vectorial capacity of these ticks are associated with genetic variation. Despite the need for detailed genetic information in this disease system, previous phylogeographical studies of these ticks have been restricted to relatively few populations or few genetic loci. Here we present the most comprehensive phylogeographical study of genome‐wide markers inI. scapularis, conducted by using 3RAD (triple‐enzyme restriction‐site associated sequencing) and surveying 353 ticks from 33 counties throughout the species' range. We found limited genetic variation among populations from the Northeast and Upper Midwest, where Lyme disease is most common, and higher genetic variation among populations from the South. We identify five spatially associated genetic clusters ofI. scapularis. In regions where Lyme disease is increasing in frequency, theI. scapularispopulations genetically group with ticks from historically highly Lyme‐endemic regions. Finally, we identify 10 variable DNA sites that contribute the most to population differentiation. These variable sites cluster on one of the chromosome‐scale scaffolds forI. scapularisand are within identified genes. Our findings illuminate the need for additional research to identify loci causing variation in the vectorial capacity ofI. scapularisand where additional tick sampling would be most valuable to further understand disease trends caused by pathogens transmitted byI. scapularis.

     
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