What phenomenon is associated with schistosome parasites and their hosts?

The phenomenon associated with schistosome parasites and their hosts is swimmer's itch. Schistosomes are parasitic flatworms that can infect humans and other animals through contact with contaminated water, where they release larvae that can penetrate the skin. When people swim or wade in waters that contain these parasites, they can experience an itchy rash known as swimmer's itch.

This condition occurs as a result of an immune reaction to the larvae. While schistosome infections can lead to more severe illnesses, swimmer's itch is the immediate reaction individuals experience when the parasites attempt to invade the skin. The connection between the schistosome parasites and swimmer's itch highlights how certain parasites interact with human activities, particularly in aquatic environments.

Other options do not pertain to schistosomes. Filariasis is linked to different parasitic worms and transmitted by mosquitoes. Guinea worm disease is caused by the larvae of the guinea worm, which is contracted by drinking contaminated water. Cholera is a bacterial infection spread through contaminated water but has no direct connection to schistosomes. Thus, the association of schistosome parasites with swimmer's itch is correct due to the specific interactions between the parasites and human skin in water environments.