What are the primary host and the intermediate host of a blood fluke?

The primary host of a blood fluke, specifically Schistosoma species, is typically a human or other mammals where the adult flukes reside in the blood vessels. The intermediate host is usually a freshwater snail, which plays a crucial role in the fluke's life cycle by harboring the larval stages before they infect the primary host. This complex interaction is essential for the transmission of schistosomiasis, a disease caused by these parasites.