You've got a good concept, although I fail to see where it fits the theme. I feel you should try to better the control, moving sideway controls fine, but jumping only when moving is not that great, plus you can get stuck on the wall... The level design is a bit unoriginal and the parasite getting stuck on the upper part of the level and not moving elsewhere is very frustrating.
As a side note : the graphic design is messy, it might be the goal but try to contrast it by having a more coherent color palet, for example the food and the main character are the same color, making it hard to see where you are at a glance. The bold stroke used for the outlines are nice, and I think you should use more of it. But great work on the transition screen, they should be faster but they're great nonetheless. Also do try to better some of the textual explanation, some are hard to understand.