Nice start, it just needs refinement.
There are lots of little things that can be done to give feedback when things happen in the game, from sounds to animations and visual effects. At the moment, unless you take the time to look at the health bar, you don't really notice it going down. While the "inflammation" shrinks after consuming the parasite, there is no feedback other than the parasite disappearing . You could also add a visual effect to the screen or player to indicate when health is going down as well.
Thanks for the game.