4546B (or at least the Crater) is completely infested with Kharra. It’s waterborne, and every organism has it in their bloodstream. The only reason why the player’s (and many other animals’) incubation stage was so long is because of the Sea Emperor’s unstable form of Enzyme 42.
In other words, you’re basically infected as soon as you enter the water.
In freedom mode, when there is no hunger or thirst, you don't have to enter the water. You also have 2 nutrient blocks and water bottles in your lifepod.