What may live for years while a parasite feeds on it?

Many animals, including certain species of fish, can live for years while hosting parasites. For example, some fish may harbor parasitic worms or protozoa that feed on their tissues and blood without immediately killing them. The host may endure the presence of these parasites for extended periods, potentially leading to chronic health issues but allowing for continued life. Other examples include mammals and birds that can carry parasites like ticks or fleas for years without succumbing to their effects right away.