Data from: Beyond Rocky Mountain spotted fever: Investigation of the presence and diversity of spotted fever Rickettsia species in ticks submitted from forestry workers
Data files
Nov 12, 2025 version files 374.66 KB
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FIA_Final_Dataset_To_Be_Uploaded_VK_20251007.csv
370.17 KB
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README.md
4.49 KB
Abstract
Ticks present a significant risk to people in the southern United States, particularly those who spend time outdoors, as they can transmit agents that cause various diseases. This study evaluated the risk of exposure to ticks positive for spotted fever group (SFG) Rickettsia species among forestry workers. From 2017 to 2021, forestry workers passively collected ticks during field surveys for the USDA Forest Service's Forest Inventory and Analysis (FIA) program. We screened 1395 ticks for SFG-Rickettsia, including Amblyomma americanum (51.5% positive, N=1,279), A. maculatum (40% positive, N=10), and Dermacentor variabilis (22.6%, N=106). The agent of Rocky Mountain spotted fever, R. rickettsii, was not detected; however, seven different SFG Rickettsia species were identified. Rickettsia amblyommatis was the most common, present in 95.7% of A. americanum ticks. The pathogenic R. parkeri was rarely found in two A. americanum nymphs and two A. maculatum males. Several Rickettsia species, such as R. montanensis, R. monacensis, Candidatus R. andeanae, and R. tamurae subsp. buchneri were identified in D. variabilis. Some of these species are suspected to be pathogenic. Rickettsia-positive ticks were detected year-round, with the highest prevalence in Tennessee and Kentucky, possibly due to larger sample submissions, which may have increased detection rates. Dermacentor variabilis were less likely to be Rickettsia-positive compared to A. americanum. Male ticks were less likely to carry Rickettsia than females and nymphs. The presence of Rickettsia-positive ticks found in this study poses a risk to forestry workers, emphasizing the importance of ongoing surveillance and education to prevent tick-borne infections.
Dataset DOI: 10.5061/dryad.0p2ngf2f8
Description of the data and file structure
Forestry workers within the USDA Forest Service’s Forest Inventory and Analysis (FIA) program conducted a multi-year, geographically extensive passive surveillance of ticks found by forest crews routinely working in wooded environments. Before starting the tick collections, forest crews reviewed a comprehensive safety lecture focused on tick precautions. Held in spring 2014, the first year of the study, the lecture emphasized safety measures. Forest inventory and analysis crew members volunteered for passive tick collection. They received tick collection kits, which included an instructional guide on tick removal, vials filled with 80% ethanol, and forceps for handling ticks. Our tick surveillance was entirely passive, relying solely on ticks found on the crew members themselves. Crew members were instructed to collect only the ticks they personally encountered and found attached or unattached on themselves, explicitly not collecting any ticks from nearby vegetation. These ticks were then placed in the provided 70% ethanol vials. Ticks collected by each crew were then sent to the FIA headquarters for initial processing before being forwarded to the University of Tennessee Medical and Veterinary Entomology Laboratory for further identification and testing. Ticks were identified at the laboratory by species, life stage, and sex using published dichotomous keys
Files and variables
File: FIA_Final_Dataset_To_Be_Uploaded_VK_20251007.csv
Description:
Variables
- No.: Individual tick number
- Date Collected: Date the tick was found (Year-month-day)
- Year: Year the tick was found
- Month: Name of Month
- Epiweek: Epidemiological week for that specific calendar year
- State: State the ticks were found
- County: The specific county ticks were found from
- genus: Genus name of the tick collected
- species: Species name of the tick collected
- life stage: The life stage of the tick collected
- Engorged: If the tick was engorged (blood fed) at the moment of collection
- Extraction Method / Tick part: The method of DNA extraction of the tick/ the body part of the tick that was extracted (abdomen/vertical half)
- Rickettsia status: The overall Rickettsia status in the tick (detected/not detected) - positive (detected), negative (not detected)
- ompA PCR: The Rickettsia status in the tick based on the ompA gene target PCR - positive (detected), negative (not detected)
- PCR-RFLP ID: The Rickettsia species in the tick based on the Restriction Fragment Length Polymorphism (RFLP) assay
- ompA identity: The Rickettsia species detected in the tick based on the ompA gene target sequence
- BLAST % Identity based on ompA gene: The percent identity match to the Rickettsia species during the BLAST match on Genbank gene database based on the ompA gene target sequence
- 23S-5S IGS PCR: The Rickettsia status in the tick based on the 23S-5S IGS gene target PCR - positive (detected), negative (not detected)
- 23S-5S IGS identity: The Rickettsia species detected in the tick based on the 23S-5S IGS gene target sequence
- % Identity based on 23S-5S IGS gene: The percent identity match to the Rickettsia species during the BLAST match on Genbank gene database based on the 23S-5S IGS gene target sequence
- gltA PCR: The Rickettsia status in the tick based on the gltA gene target PCR - positive (detected), negative (not detected)
- gltA identity: The Rickettsia species detected in the tick based on the gltA gene target sequence
- % Identity based on gltA gene: The percent identity match to the Rickettsia species during the BLAST match on Genbank gene database based on the gltA gene target sequence
- % Identity based on gltA gene target sequence: results from BLAST % Identity analysis based on the gltA gene. Not Sequenced: gltA gene was not sequenced for that sample, so no BLAST comparison could be done. Negative: gltA gene was sequenced, but no Rickettsia or other relevant match was found in the BLAST database. Rickettsia amblyommatis –100%: gltA gene sequence from that sample matched Rickettsia amblyommatis with 100% identity in the BLAST search.
Code/software
Opensource CSV File