This is why you don’t swim in the Amazon
This post was published 4 years 7 months 21 days ago which may make its actuality or expire date not be valid anymore. This site is not responsible for any misunderstanding.Aside from the larger reptiles, snakes, and sharks that will tear your limbs off, you must also worry about the Candiru [Vampire Fish]:

The fish is said to be addicted to the taste and smell of human urine. [...] The candiru tastes the urine stream and follows it back to the human. It then swims up the anus and lodges itself somewhere in the urinary tract with its spines. Blood is drawn, and the candiru gorges itself on the blood and body tissue, its body sometimes expanding due to the amount of blood consumed.
I’m assuming that the word anus in the above statement is a typo which should be penis / vagina. Nonetheless, I for one will never pee in the Amazon or any murky water for that matter.