Water is capable of dissolving a variety of different substances, which is why it is such a good solvent. And, water is called the "universal solvent" because it dissolves more substances than any other liquid. This allows the water molecule to become attracted to many other different types of molecules.
Parasitism is symbiotic relationship where an organisms lives in or on it's host thereby feeding and causing harm on it host. Examples of such relationship is parasites like roundworm, ticks, fleas that feed on humans and cause harm.