Blood Infection:
Roll on "Regions, Random determination of:" in the R-Section of the Basic Rules Book. When you have rolled up a random region, continue rolling until you are able to roll a random creature within one of the 8 Settings. If the creature rolled has blood, or blood-like bodily fluids, this will be the blood infection you have.
It will then be up to the Game Master to interpret what the blood infection means in the life of your newly created character.
G.M.: You may wish to keep this a secret from the player -- for suspence during game-play (i.e., this blood infection may manifest itself at a later time.
Next step: Character's Background