Renal lesions, including necrotizing granulomatous nephritis, associated with Renicola mirandariberoi (Digenea: Renicolidae) in Sula leucogaster (Suliformes: Sulidae) from the South Atlantic

Abstract Seabirds are frequently stranded along the Brazilian coast due to anthropogenic, metabolic, infectious, or parasitic diseases. This study describes renal lesions caused by the trematode Renicola mirandariberoi in Sula leucogaster (brown booby) found along the Campos and Espírito Santo Basins, Southeast Brazil. Among 74 individuals necropsied between April 2021 and December 2024, 26 (35.1%) presented renal trematodiasis. Histological examination revealed dilation of collecting ducts containing adult trematodes, necrosis of tubular epithelial cells, and interstitial lymphohistiocytic inflammation. In 19.2% (5/26) of the cases, extraluminal mono-operculate eggs caused granulomatous nephritis, and only one S. leucogaster presented a renal interstitial granuloma associated with parasite eggs. In 69.2% (18/26) of the affected birds, kidney lesions were the only histological findings. Parasites were identified as R. mirandariberoi based on morphological and morphometric features, and the ultrastructure of mono-operculate eggs was characterized by scanning electron microscopy. These findings indicate that R. mirandariberoi infection may play a significant role in the morbidity and mortality of S. leucogaster along the South Atlantic coast.