Lethal effects of praziquantel and albendazole, on the cercariae of Echinochasmus sp. (Dietz, 1909) in-vitro

Echinochasmidae are considered one of the digenean intestinal parasites of carnivorous mammals and humans. Some larvicidal medications, such as praziquantel and albendazole, were employed to interrupt the life cycle of Echinochasmidae, which may cause harmful and serious effects on the domestic fish, ducks, and humans in our ecosystem. Cercariae of Echinochasmus sp. (gymnocephalus type) were harvested by exposing snails to strong artificial illumination. The emerging cercariae were exposed in vitro to different concentrations of praziquantel and albendazole at the same period of incubation 12 h. Using probit analysis in SPSS version 25, the lethal concentrations 50 and 95% were determined. They were 0.036 and 0.82 ppm, respectively, for praziquantel and 5.3 and 9.2 ppm, respectively, for albendazole. The ultrastructural changes using scanning electron microscope on the tegumental surface of the treated cercariae with the two drugs were compared to the untreated cercariae. The untreated cercariae have a pear-shaped body with a long tail. The oral sucker is armed with a spiny collar and decorated with ciliated and unciliated sensory papillae. The cardinal ventral sucker has a thick, muscular wall. The cercarial tail is decorated with parallel longitudinal tegumental processes and spherical, unciliated papillae. In comparisons, cercariae treated with both drugs lost all healthy morphological features, but in varying degrees and effects between the two drugs. Our findings suggest that the use of both drugs can be recommended during the design of control strategies to combat this type of intestinal parasite.