They embodied a popular character trope in ancient Greek writing: one that originated as a form of comic relief. As part of NPR's "Word of the Week" series, we're explaining how the word "parasite" started as a joke and became anything but funny. A biological threatToday, most people know of a parasite as a tiny organism, one that needs a host to live. "Bring back the funny parasite," Martin said. That brings us to the microscopic gastrointestinal parasite that's wreaking havoc right now: Cyclospora, which has caused outbreaks in at least nine states.