Blood Parasites of the Phylum Apicomplexa and Hematological Values in European Pond Turtles (Emys orbicularis) from Lublin Voivodeship, Eastern Poland.

This study aimed to detect and characterize intracellular blood parasites of the phylum Apicomplexa in freshwater turtles. Microscopic analysis identified developmental stages of gamonts and premeronts belonging to the genus Haemogregarina, while molecular analyses confirmed the presence of Haemogregarina stepanowi, Haemogregarina spp., and Hepatozoon sp. The mean parasitemia was 29.7 parasites per 10,000 erythrocytes. Hematologic examinations showed elevated basophil and eosinophil counts in infected individuals, indicating an immune response to the infection. Phylogenetic analyses supported the close genetic relationship of isolates from this study with hemoparasites found in other freshwater turtle species. Overall, these results contribute to the understanding of the diversity and genetic relationships of hemogregarine species in freshwater turtles.