Ticks, and tick-borne bacterial pathogens found on hard ticks (Acari: Ixodidae) on cattle in the Central River Region of The Gambia
Data files
Jul 09, 2025 version files 18.23 KB
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Data_Ticks_from_Gambia.xlsx
15.48 KB
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README.md
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Abstract
Ticks are significant vectors of pathogens affecting both animals and humans, with the climate in Sub-Saharan Africa providing ideal conditions for their growth. However, there is limited data on ticks and tick-borne pathogens (T&TBPs) in cattle in The Gambia. This study aimed to identify tick species on cattle and conduct molecular screening for T&TBPs. A total of 92 ticks were collected from 306 indigenous cattle. Ticks were first identified morphologically using taxonomic keys and then confirmed molecularly through DNA sequencing. DNA was extracted from the right fourth leg of six representative ticks for species confirmation, while 77 whole adult ticks were used for screening T&TBPs. Screening PCR assays targeted Anaplasma marginale msp1β gene, Ehrlichia spp. dsb gene, and hemotropic Mycoplasma spp. 16S rRNA gene. Ehrlichia-positive samples underwent additional assays targeting the sodB, 16S rRNA, and groEL genes, followed by Sanger sequencing and phylogenetic analyses. A total of 92 (53 M, 37 F, and two nymphs) ticks were collected from 30/306 (9.8%; 95% CI: 5.6 - 12.2 %) cattle with a mean of 3.1 ticks per animal. Adult ticks were identified as Hyalomma marginatum (73/92; 79.3%; 45 M and 28 F), Amblyomma variegatum (eight/92; 8.7%; eight M), Hyalomma rufipes (four/92; 4.3%; four F), and Rhipicephalus evertsi (1/92; 1.1%; one F). The 16S rRNA sequences of six (four engorged females and two nymphs) ticks showed 98.6–100% identity with reference sequences from Rhipicephalus geigyi. Twelve out of 77 (15.6%) ticks tested positive for at least one TBP. Eight H. marginatum (six M, two F) (10.4%) were positive for Ehrlichia spp. dsb gene, three H. marginatum (two M and one F) (3.9%) for A. marginale, and two (one H. marginatum F and one A. variegatum M) (2.6%) for hemotropic Mycoplasma spp. All Ehrlichia-positive samples showed 100% detection for the 16S rRNA gene and 62.5% for the sodB gene. BLASTn analysis revealed 99.3–99.7% identity with Ehrlichia sp. from Brazil and 98.2-99.3% identity with E. minasensis from Panama and Pakistan. Phylogenetic analysis grouped the sequences from this study with Ehrlichia spp. and E. minasensis from ticks in the Czech Republic and Brazil. This study identified various tick species and pathogens in cattle from The Gambia, including the first report of E. minasensis, A. marginale, and hemotropic Mycoplasma spp. in the country. These findings highlight the importance of ongoing surveillance and research on tick-borne diseases in the region.
Access this dataset on Dryad: DOI: 10.5061/dryad.34tmpg4v6
Description:
Our data contains one file:
Data_Ticks_from_Gambia.xlsx
Data Structure and Potential Use: This dataset is organized in an Excel spreadsheet format with separate sheets and clearly labeled columns to facilitate ease of use.
Sheet 1: Identified ticks
Tick Metadata Sample ID: Unique identifier for each tick.
Host Animal ID: Identifier linking the tick to the individual cattle host.
Tick Species: Determined using morphological keys (e.g., Hyalomma marginatum, Amblyomma variegatum, etc.).
Sex & Life Stage: Recorded as male (M), female (F), or nymph.
Sheet 2: TBPs analysed
PCR Results Sample ID: Cross-referenced with Sheet 1.
Pathogen Target Gene: Indicates which gene was tested (e.g., dsb, 16S rRNA, sodB for Ehrlichia spp.).
PCR Result: Positive or negative.
Pathogen Identified: Name of the pathogen detected, if any.
Glossary
This includes explanations of technical terms and acronyms for non-specialists:
PCR: Polymerase Chain Reaction - a method to amplify DNA.
qPCR (Quantitative PCR), also called real-time PCR, this technique quantifies the amount of target DNA present in a sample, providing both detection and approximate load (if standards are used). Results are often expressed as Ct values (cycle threshold).
dsb gene: A target for detecting Ehrlichia spp.
16S rRNA gene: A universal marker for bacterial identification.
sodB and groEL: Genes used to characterize Ehrlichia and related organisms.
Notes
Explanation of “n/a” Values in the dataset: The label “n/a” is used in this dataset to indicate instances where data are either not available or not applicable, depending on the context. Below is a breakdown of how this applies to different parts of the data:
Unsequenced Samples (Positive and Negative): “n/a” is used for both positive and negative samples that were not sequenced. Sequencing was performed only on a subset of PCR-positive samples due to resource constraints, limitations, and prioritization of the representative.
qPCR Results – Cq Values: Cq (cycle quantification) values are only generated for qPCR-positive samples. Negative samples do not have valid Cq values and are marked as “n/a” in the corresponding columns.
Gene Characterization – Only Performed on Positives: Downstream gene-specific PCR assays (e.g., sodB, msp1a, groEL) were conducted only on samples that tested positive in initial screenings. Therefore, samples that were negative in screening assays are marked “n/a” in those columns to indicate that these tests were not applicable.