so how i would like parasites to work is if you get an infection for as long as you have the infection you can get a parasite which has to be cured with some kind of antibiotic. There would be different parasites that would have different effects. What i was thinking of is something like this.
Parasite 1: removes agi and str and const
Parasite 2: causes infection to last longer
Parasite 3: makes it so that energy can't go above 5000%.
Parasite 4: causes you to be impregenated with a parasitic life form that will live off of your body causing your energy to constantly drain forcing you to keep eating all the time in order to not die, then after a week you give birth to a parasitic life form that will instantly try to kill you the moment it is birthed.