Identification of Livestock Ticks and Molecular Characterization of Tick-Associated Microorganisms in Senegal.

Ticks are obligate hematophagous arthropods at all developmental stages, primarily feeding on terrestrial vertebrates. They serve as vectors for numerous pathogens affecting both humans and animals. Accurate tick species identification currently requires an integrated approach combining morphological, molecular, and proteomic techniques. As part of a tick-borne disease surveillance program conducted in 2023 in the Kaffrine and Tambacounda regions of Senegal, ticks were collected from livestock in domestic environments to investigate the presence of Rickettsia spp. and other associated microorganisms. Specimens were identified using morphological keys, molecular markers, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), while pathogens were detected using quantitative PCR (qPCR) and sequencing. A total of 212 ticks were collected, representing three genera (Amblyomma, Hyalomma, and Rhipicephalus) and six species: Amblyomma variegatum (n = 60), Hyalomma rufipes (n = 52), Hyalomma truncatum (n = 22), Rhipicephalus evertsi evertsi (n = 59), Rhipicephalus linnaei (formerly Rh. sanguineus tropical lineage) (n = 9), and Rhipicephalus (Boophilus) decoloratus (n = 3). Among these, 36.8% (78/212) tested positive for at least one microorganism. Rickettsia spp. and Coxiella burnetii were each detected in 7.4% (16/212), while members of the Anaplasmataceae family were found in 5.2% (11/212). Specific identification confirmed the presence of Rickettsia africae, R. aeschlimannii, Anaplasma ovis, A. phagocytophilum, "Candidatus Ehrlichia rustica", "Candidatus Ehrlichia urmitei", Theileria ovis and T. mutans. These findings highlight the necessity of combining identification methods to enhance taxonomic precision, especially for closely related or morphologically ambiguous specimens. The presence of zoonotic pathogens reinforces the need for improved surveillance and awareness among health professionals.