Giardia intestinalis, a cosmopolitan zoonotic parasite, is one of the most common causes of protozoal diarrhea in both humans and animals worldwide. Although G. intestinalis has been detected in many animals, information regarding its prevalence and genotype in Chinese racehorses is scarce. In the present study, we investigated the prevalence of G. intestinalis in racehorses and performed molecular characterization of the pathogen to assess its zoonotic potential. Two hundred and sixty-four racehorse fecal samples from six equestrian clubs located in different regions of the Sichuan province of southwestern China were examined. Nested polymerase chain reaction (PCR) analysis of the gene encoding triose-phosphate isomerase (tpi) showed the prevalence of G. intestinalis to be 8.3% (22/264), and the prevalence in different clubs varied from 3.6% to 13.5%. Three assemblages were identified in the successfully sequenced samples, including the potentially zoonotic assemblages A (n = 5) and B (n = 14), the mouse-specific assemblage G (n = 3), and a mixed A and B assemblage. Sequence analysis of tpi, glutamate dehydrogenase (gdh), and beta giardin (bg) loci revealed that the majority of sequences isolated from assemblage A were identical to the subtype AIV and assemblage B isolates showed variability among the nucleotide sequences of the subtype BIV. Using the nomenclature for the multilocus genotype (MLG) model, one each of multilocus genotypes A (MLG1) and B (MLG2) were identified, with MLG2 being a novel genotype. To the best of our knowledge, this is the first study to investigate G. intestinalis in Chinese racehorses. The presence of both animal and human assemblages of G. intestinalis in racehorses indicated that these animals might constitute a potential zoonotic risk to human beings.

Piroplasmosis is a major tick-borne disease that causes significant economic losses in livestock production across various regions. The present study aimed to provide a comprehensive assessment of the prevalence of bovine piroplasmosis in Gansu and Qinghai provinces, China, offering crucial baseline data for the development of effective control and prevention strategies. A total of 736 bovine blood samples were collected from Tianshui, Pingliang, and Lanzhou in Gansu, and Xining and Haidong in Qinghai. These samples were analyzed using PCR with universal Piroplasma primers targeting the 18S rRNA gene. The overall prevalence of bovine Piroplasma infection was found to be 25.54% (188/736). Three Theileria species were identified, including T. orientalis (14.27%, 105/736), T. annulata (10.73%, 79/736), and T. sinensis (0.54%, 4/736). No cases of Babesia or mixed infections were detected in this study. Notably, T. sinensis was reported for the first time in Pingliang, highlighting its potential expansion in the region. In conclusion, bovine piroplasmosis remains prevalent in both Gansu and Qinghai provinces, with T. orientalis being the predominant species. These findings underscore the need for strengthened surveillance and improved strategies for the prevention and control of piroplasmosis in the region.

Theileria annulata causes tropical theileriosis in cattle, yet the molecular basis of host–parasite crosstalk across intracellular stages remains incompletely defined. We combined RNA sequencing and untargeted metabolomics to profile paired uninfected and infected bovine leukocytes (schizont stage) and erythrocytes (piroplasm stage), together with purified schizonts and piroplasms. Integrated analyses revealed pronounced, cell type-specific reprogramming. Infected leukocytes showed activation of immune signalling, amino acid metabolism and energy-producing pathways, consistent with leukocyte transformation, whereas infected erythrocytes preferentially engaged glutathione metabolism and redox homeostasis. Parasite stage comparisons uncovered extensive transcriptional and metabolic rewiring, including stage-biased expression of mitochondrial components, antioxidant systems and putative stage-regulated transcription factors. These coherent host–parasite adaptations likely facilitate parasite survival and persistence within distinct cellular niches. This work delineates a stage-resolved multi-omics landscape of T. annulata infection spanning host and parasite compartments and identifies signalling and metabolic pathways that merit functional validation as candidates for improved diagnostics and targeted interventions against bovine tropical theileriosis.

Theileria annulata, an apicomplexan parasite, causes lymphoproliferative disease in cattle and threatens the bovine industry in tropical and subtropical regions. To clarify life-cycle mechanisms and parasite-host interactions, we conducted high-resolution Orbitrap proteomic and phosphoproteomic analyses of the schizont and piroplasm stages. In total, we confidently identified and quantified 2,093 proteins; among these, 459 proteins were observed in a phosphorylated state, comprising 5,069 distinct phosphorylation sites. Functional enrichment analysis of differentially abundant proteins indicated stage-associated remodeling of genetic information processing, carbohydrate, lipid, and amino-acid metabolism, and core cellular processes. Stage-associated proteins were linked to host-parasite interaction, mitochondrial function, and metabolic adaptation. Schizonts showed broader proteomic and phosphorylation profiles consistent with higher biosynthetic and energy demands. In contrast, piroplasms exhibited a more restricted proteomic profile associated with erythrocyte adaptation and invasion-related functions. Together, these stage-resolved datasets provide a reference for proteome and phosphoproteome remodeling across development and prioritize candidate stage-associated proteins and phosphosites for future functional validation.