Patient Zero (gg_adamski, c_ghost)

The world is facing a pandemic situation.  The virus begins to spread throughout the city. You need to be quick and check on people who have been infected, check the places in town where they attended during the turns, while trying to find out who is the Patient Zero, who's the only one immune to the disease. 

Find the patient and isolate him/her in order to develop a new vaccine and save people before it's too late.