Genetic Diversity of Theileria parva and Anaplasma spp. Isolated From Ticks Collected From Kiambu County, Kenya.

Abstract

Environmental changes and human activities such as deforestation and expansion of agricultural land are increasing tick-borne diseases including Anaplasmosis, Babesiosis, Ehrlichiosis, and Theileriosis. These diseases, which affect animals, can be transmitted to humans through tick bites. Kiambu County's warm, wet climate provides an environment conducive to tick breeding and development. This study investigated the circulation and genetic diversity of Theileria parva and Anaplasma spp. in tick samples collected from Kiambu County, Kenya. Ticks were collected from cattle, goats, and sheep using animal grooming methods and morphologically identified and organized into 129 pools. Total DNA was extracted from tick pools using the sodium dodecyl sulfate extraction method. The 18S rRNA hypervariable region was amplified for T. parva detection, and the 16S rRNA gene was used for Anaplasma spp. detection. A total of 716 ticks were collected, with Rhipicephalus evertsi evertsi (n = 585, 81.7%) being the most abundant species. Molecular analysis indicated the presence of T. parva in n = 8 pools of Rh. e. evertsi. Anaplasma species was detected in three pools of Rh. e. evertsi, one pool of A. variegatum, and one pool of H. truncatum. Phylogenetic analysis revealed that eight T. parva samples clustered closely with isolates from Uganda and Mexico, suggesting potential historical or ecological links between regional isolates and international strains, although direct transmission cannot be confirmed. For Anaplasma spp., phylogenetic analysis identified Anaplasma ovis and Anaplasma bovis in ticks collected from cattle and sheep, including Rh. e. evertsi, A. Variegatum, and H. truncatum, with single nucleotide polymorphisms (SNPs) identified within the Anaplasma sequences. The findings emphasize the importance of continued molecular surveillance of tick-borne pathogens, characterization, and the development of targeted tick control measures to mitigate the impact of tick-borne diseases in livestock.