How do you square parasites with your understanding of the fall

Hey, just thought of another interesting question. What about parasites – tapeworms, gut bacteria, leeches? If everything God created was good, what does their existence imply? Does it suggest a gap between our standards of goodness and God’s? How do we explain their parasitic nature? Is this something that they acquired after the fall? If it was always there, how do we reconcile their feeding off us, eating us, drinking us, with standard interpretations of the fall?