Abstract
Schistosoma mansoni is the main factor of human schistosomiasis which is responsible for high rates of mortality. Recently, the use of alternative biological control agents has gained importance in disease control because the intensive use of molluscicides is very harmful to human health and poses risks to the environment. In the present work, the potential effect of two freshwater algae, Amphora coffeaeformis and Scenedesmus obtusus , on the immune response of Biomphalaria alexandrina snails against infection with S. mansoni was investigated. Two different concentrations 1 and 2 g L − 1 from each dried algal material were tested on snails before exposure to miracidial infection by one day. The use of Amphora coffeaeformis has a greater immunostimulatory effect than Scendesmus obtusus at a low concentration of 1.0 g L − 1 . The tested algae affected the snail’s hemocytes and its immune response to S. mansoni as evidenced by a significant decrease in infection rate and cercariae production. In addition, increasing in total hemocyte count, the formation of vacuoles, the appearance of several pseudopodia, and the formation of coarse granules in hemocytes of infected snails treated with A. coffeaeformis . Intense tissue reactions were also observed. In conclusion, it was confirmed that these algae can be used as an immunostimulant in the prevention and control of S. mansoni .