Author ORCID Identifier

https://orcid.org/0000-0002-1273

Date Available

4-25-2023

Year of Publication

2023

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department/School/Program

Entomology

First Advisor

Dr. Subba Reddy Palli

Abstract

Tick-borne diseases are an emerging threat to human and animal health. In Kentucky, tick-borne disease surveillance has identified rising incidences of spotted fever rickettsiosis, ehrlichiosis, and Lyme disease. Since these diseases occur through the bites of infected ticks, effective prevention efforts are reliant upon knowing where the risk of exposure to tick bites exists. Historical data on tick distribution in Kentucky is variable, with very little reported on a statewide scale, leaving vector control workers, public health personnel, physicians, veterinarians, and others to rely on outdated, intermittent, or out-of-state information. In my dissertation, I surveyed ticks and select tick-borne pathogens causing spotted fever rickettsiosis, ehrlichiosis, and Lyme disease in Kentucky from 2019-2022.

Chapter 1 reports data on Ixodes scapularis and Borrelia burgdorferi, the agent of Lyme disease. Six hundred and seventy-four I. scapularis were collected from 58 counties and the Lyme disease spirochete, B. burgdorferi, was detected in ticks from 16 of these counties adding to the few previous reports of I. scapularis and B. burgdorferi in Kentucky. This tick was collected each month of the year, though not every month of the study period, and primarily collected from forested environments.

Chapter 2 reports data on Amblyomma americanum and Ehrlichia chaffeensis, the primary agent of ehrlichiosis. Eight thousand forty-seven A. americanum were identified from 115 counties and E. chaffeensis was detected in ticks from 44 counties. This tick was collected most frequently in forested environments from March to November, with peak activity in May and June for adults and nymphs, and August for larvae.

Chapter 3 reports data on Dermacentor variabilis and Amblyomma maculatum infected with Rickettsia rickettsii and R. parkeri, both of which are agents of spotted fever rickettsiosis. One thousand one hundred seventy-six D. variabilis were collected from 99 counties, primarily in grassland dominant and mixed grassland-forest habitats. The Rocky Mountain spotted fever agent, R. rickettsii, was detected in ticks from three counties. Only 26 A. maculatum were collected from four counties, but no R. parkeri was detected in the ticks tested. This research is the first statewide, multi-year surveillance effort for ticks and tick-borne pathogens in Kentucky. Overall, these data report on the distribution, abundance, and seasonality of these important tick vectors, and the distribution and estimated prevalence of pathogens causing major tick-borne diseases in Kentucky.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2023.077

Funding Information

This study was supported by the National Institute for Occupational Safety and Health/CDC Grant (no.:5T42OH010278) from 2021-2023, and the Kentucky Department for Public Health Grant (no.:PON27282000001848) from 2019-2023.

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