Molecular epidemiology and geographic distribution of Theileria spp. in Kazakhstan: a countrywide cattle survey and a southern sheep survey

BackgroundTheileriosis is endemic in Central Asia; however, the geographic distribution and genetic diversity of Theileria spp. in livestock in Kazakhstan remain poorly characterized. This study aimed to determine the occurrence, geographic distribution, and genetic diversity of Theileria spp. in cattle and sheep in Kazakhstan.MethodsBlood samples from 6,224 cattle from 172 settlements across all 17 provinces of Kazakhstan and 1,467 sheep from 52 settlements in five southern provinces were collected during July–August 2022 and 2023. Samples were screened using a genus-level PCR targeting the 28S ribosomal RNA (28S rRNA) gene, followed by bidirectional sequencing for species identification. Selected T. orientalis-positive samples were further characterized by major piroplasm surface protein (MPSP) genotyping.ResultsAmong cattle, 2,142 out of 6,224 (34.4%) tested positive by PCR for at least one species of Theileria. Theileria annulata, T. orientalis, and T. sinensis were detected in 27.1, 15.1, and 0.5% of cattle, respectively. The simultaneous detection of two or three species of Theileria was recorded in 508 of 2,142 (23.7%) PCR-positive cattle. Theileria orientalis was detected in all 17 surveyed provinces, T. annulata in 16, and T. sinensis in five. MPSP analysis identified T. orientalis genotypes 1 (“Chitose”), 2 (“Ikeda”), and 3 (“Buffeli”). Among sheep, 169 out of 1,467 (11.5%) tested positive by PCR; T. ovis, Theileria sp. genotype OT3, and T. annulata were detected in 5.5, 4.4, and 2.6% of the animals examined, respectively. T. orientalis genotype 2 (“Ikeda”), T. sinensis, and Theileria sp. genotype OT3 were detected in Kazakhstan for the first time.ConclusionThe study demonstrated a widespread but geographically heterogeneous detection of Theileria species among sampled cattle across Kazakhstan and enabled the first molecular characterization of infections caused by Theileria species in sheep in that country. The detection of T. orientalis genotype 2 (“Ikeda”), T. sinensis, and Theileria sp. genotype OT3 expands the known diversity of Theileria species circulating in Central Asia. Since sampling was not conducted on a probabilistic basis, the observed PCR positivity should not be interpreted as representative of Theileria prevalence in the national livestock population. The data obtained serve as a starting point for targeted molecular surveillance of livestock and their associated tick vectors.