A Drain or Suppress vs Dexterity and Stun (I favor the Drain), with a delay of days or weeks will work. Unless mistaken, I think the 5th ed mentions something about using negative Combat Levels and using them against others but I'd go with the Drain.
ex. 4d6 Dex Drain, 1d6 Stun Drain, delay 1 week. Add 'Range' if concept fits.
Depending on the disease, you might want to add:
3d6 Int Drain, delay 1 week, only to lower skill rolls, to represent the increased difficulty in thinking.