"Parasites evolved for millions of years in this planet have exactly the same right to exist and to be saved as any other earthlings. Stop hitting me just because you don't like the truth, please". More realistic.

They are a big part of earth biodiversity and provide services to the ecosystem or the host. Services that sometimes no other can provide. Some parasites can clean in theory the host body of poisonous mercury. Could we train parasites to eat cankerous tumors in the future?