CONTAGIOUS- something very easy to spread or pass
EPIDEMIOLOGY- Epi "upon" Demi " people" Ology "Study" The study of what is upon people
INFECTION- when a pathogen invades and begins growing within a host
PATHOGEN- Path "Disease" Gen "Begining" The begging of disease
PATIENT ZERO- The person from whom the disease originated
VIRULENT- Viru " Poison" how poisonous something is