Figure 1.

The schistosome life cycle is complex, with morphologically distinct stages occupying several ecological niches. Infective cercariae (a) swim in fresh water to find and infect a mammalian host. After host invasion, cercariae transform into schistosomula (b) and adapt to survival in the host bloodstream. The schistosomula mature into adult male or female schistosomes (c), which pair and produce eggs (d). Eggs are excreted from the host. In fresh water, the eggs hatch into miracidia (e), which infect a snail host and develop into sporocysts (f). Daughter sporocysts generate infectious cercariae, completing the life cycle.