Spirochiidiasis in Stranded Olive Ridley Turtles (Lepidochelys olivacea) Long the Northern and Central-Northern Chilean Coast

The olive ridley turtle (Lepidochelys olivacea) is the second smallest and most abundant of the seven sea turtle species worldwide, currently distributed across approximately 80 countries. However, due to various anthropogenic and environmental pressures, its populations are declining and categorized as "Vulnerable" by the IUCN. This study describes the post-mortem macroscopic and microscopic detection of spirorchiids and associated lesions in six adult female olive ridleys stranded along the Northern and Central-Northern Chilean coast between November 2024 and January 2026. Macroscopic findings primarily revealed alterations in the gastrointestinal, reproductive, and vascular systems, characterized by transmural granulomatous lesions and mucosal thickening. Histopathological analysis confirmed the presence of these cryptic parasites in multiple organs, including the intestine, reproductive tract, vasculature, liver, spleen, and adrenal glands, with varying degrees of severity. These findings confirm the presence of spirorchiidiasis in olive ridley turtle in Chile, which may be directly or contributorily associated with stranding and mortality events. Molecular characterization is essential to determine whether this agent corresponds to a known species or represents a novel cryptic parasite taxon in the South-Eastern Pacific.