Eimeria in chickens: Recent advances in host-pathogen interactions, molecular insights, and control strategies.
Avian coccidiosis, caused by Eimeria spp., remains a major parasitic disease of poultry and imposes significant economic burdens on the global poultry industry. This review systematically synthesizes key advances over the past decade concerning host-Eimeria interactions, molecular regulatory mechanisms, and novel control strategies, while contextualizing these findings with earlier seminal discoveries. In recent years, novel diagnostic tools based on molecular detection and antigen capture have emerged, offering improved sensitivity and interspecies specificity over conventional methods. These techniques complement traditional approaches relying on oocyst morphology and histopathology, and provide critical support for accurate assessment of field infection status, species and genotype discrimination, monitoring of drug-sensitivity shifts, and elucidation of transmission dynamics. Epidemiological investigations have further revealed the impacts of rearing management, environmental temperature and humidity, host genetic background, and gut microbiota composition on infection kinetics, underscoring the necessity of integrating biosecurity and precision management into regionally tailored control programs. Utilizing chicken embryo and chick infection models, in conjunction with CRISPR/Cas9 gene editing, single-cell transcriptomics, and high-resolution proteomics, researchers have gained deeper insights into key regulatory genes governing invasion, asexual multiplication, and gametogenesis, as well as invasion-related effector molecules and resistance-associated markers, thereby laying a foundation for the identification of novel intervention targets. In immunology, growing knowledge of the intestinal epithelial barrier response, Th1/Th17 polarization, regulatory T-cell function, and immune evasion strategies (e.g., antigenic variation and downregulation of host antigen presentation) provides a theoretical basis for the rational optimization of subunit vaccines and live oocyst vaccines. On the therapeutic front, novel combination regimens of conventional anticoccidials and plant-derived bioactive compounds have shown efficacy in reducing oocyst shedding and alleviating intestinal lesions, while nanoparticle-based targeted delivery systems and adjuvant combination strategies are being explored to enhance drug bioavailability or vaccine-induced protective immunity. Nevertheless, the effective integration of ever-expanding omics data, immune-protective mechanisms, and field-applicable control measures, while concurrently addressing drug residues and resistance management, remains a central challenge for achieving sustainable coccidiosis control.