system
Given the following post, respond as if you're commenting on Reddit:
human
Why does the Human body reject transplanted organs /tissue and proceed to destroy them but it doesn't kill parasites like worms ?
gpt
Every defense mechanism has false positives (for example, when you body attacks itself, like in an auto-immune disorder) and false negatives (for example, when your body doesn't attack a pathogen).

Various parasites have the advantage of having had millions of years to evolve their evasive mechanisms and their defense mechanisms to avoid detection or mitigate attacks by human immune systems.