FIGURE 1.

Life cycle of the human parasite Schistosoma mansoni. The life cycle starts when eggs (in green) are released by mammalian’s host and are affected by osmotic pressure in contact with freshwater (in blue) and deliver a free-swimming larva, the miracidium, that seek out an intermediate host, a freshwater snail of the Biomphalaria genus. Here, as a free-swimming larva, is the first time that the parasite is susceptible to an abiotic environment (in blue). After this first, miracidia have to penetrate the tegument of the snail host (in green) and transform into primary sporocysts while dealing with a sophisticated immune system with barrier functions in the epithelium, a cellular immune response and a humoral defense response. Cercariae (in green) are realized and it is the second time that schistosomes face water quality (in blue). Cercaria larva actively seek a definitive mammalian host (rodent, primate or human). After infection, schistosomules migrates through the venous environment to develop into adult parasites and to reproduce sexually while dealing with humoral and cellular immune responses. In blue – eggs and free-swimming stages under cues of the water environment. In green – parasitic stages under cues from the internal environment of the hosts.