Ciguatera is a form of food poisoning caused by eating contaminated what?

why are people eating the viscera and sex organs of fish?

Fish are not "contaminated" with ciguatera, which suggests it comes from a dirty surface. The description is correct in that ciguatera comes from the regular diet of the fish. We don't get "contaminated" with asparagus, but we contain asparagus after eating it, which we can often detect when we urinate.