Biocidal Effect Of Nigella Sativa, Pelargonium Graveolens And Azadirachta Indica Extracts On Bulinus Truncatus Snail And Aquatic Stages Of Schistosoma Haematobium

Background: Schistosomiasis is a public health problem of social and economic importance in the developing world. Schistosomiasis haematobium is still endemic in many foci along the Nile valley, especially in El Fayoum and Beni-Suef governorates. Chemotherapy and snail eradication are the most important control measures with few studies that dealt with its snail intermediate host, Bulinus truncatus. Because of drug resistance and recurrence of exposure to infection, snail control becomes a better method for control, keeping in mind that chemical molluscicides may have toxic effects on non-target organisms.Objectives: The aim of the study is to search for biologically derived molluscicides such as plant extracts, that are less expensive, available, biodegradable, non-toxic and easily applicable than synthetic ones.Material and Methods: The effect of oil extracts of three natural plants; Nigella sativa, Pelargonium graveolens and Azadirachta indica were investigated as molluscicidal agents against B. truncatus snail. Histopathological examination of the soft tissue of the snail was performed after its removal from the shell and its staining with hematoxylin and eosin (HE). Effect of the three plants on miracidia and cercariae of S. haematobium was also evaluated.Results: The potent molluscicidal effect was demonstrated by disturbance of normal histology and presence of vacuolated tissues evident by microscopical examination of the dead snails after HE staining. A schistosomicidal effect was also recorded against aquatic stages of the parasite, demonstrated by reduction in the movement of the miracidia, followed by their sinking down together with the cercariae. N. sativa showed the most potent molluscicidal, miracidicidal, as well as cercaricidal activities, followed by P. graveolens, while A. indica had the least effect.Conclusion: These findings recommend the use of the studied plant extracts as safe and effective agents in the control of S. haematobium in Egypt.