Morphological characterization and in vitro evaluation of Dendronephthya sp. extract against Balantidium sp. infecting Amietophrynus kassasii in New Valley Governorate, Egypt

Abstract

Abstract Background Balantidium spp. are intestinal ciliates reported in various vertebrate hosts, including amphibians, yet their occurrence remains poorly documented in many regions. This study aimed to investigate the infection rate and morphological characteristics of Balantidium sp. isolated from Amietophrynus kassasii in the New Valley, Egypt, as well as to evaluate the in vitro antiprotozoal activity of Dendronephthya sp. extract. Methods A total of 27 frogs were collected between May and July 2023 from New Valley Governorate, Egypt. Intestinal contents were examined for the presence of Balantidium sp., and the isolated parasites were subjected to ultrastructural characterization using scanning electron microscopy (SEM). The antiprotozoal activity of Dendronephthya sp. methanolic extract was evaluated under in vitro conditions at different concentrations (25, 50, and 100 µg/mL) and exposure times (15, 30, and 60 min). Results The infection rate of Balantidium sp. in frogs was 14.8%. SEM analysis revealed distinct morphological features of both trophozoite and cyst stages, including variation in cyst architecture and well-defined ciliary patterns in trophozoites. Dendronephthya sp. extract induced progressive ultrastructural alterations in trophozoites, with severe damage observed at 100 µg/mL after 60 min, including complete ciliary loss, surface fissuring, cytoplasmic disintegration, and advanced degeneration, whereas lower concentrations produced limited structural effects. Conclusion The present findings provide baseline epidemiological and ultrastructural data for Balantidium sp. infecting A. kassasii and demonstrate the antiprotozoal activity of Dendronephthya sp. extract under controlled conditions. Further studies are required to assess parasite viability and elucidate the underlying mechanisms of action.