Caused by a common virus called herpes simplex (HSV-1), cold sores are contagious and can spread from person to person through skin-to-skin contact or by sharing items (such as eating utensils, lip balm, towels, cosmetics, and food), even when they aren't visible.
Infectious mononucleosis, or mono, refers to a group of symptoms usually caused by the Epstein-Barr virus (EBV). It typically occurs in teenagers, but you can get it at any age. People with mono often have a high fever, swollen lymph glands, and a sore throat.
Infectious mononucleosis (mono) is a contagious illness typically caused by the Epstein-Barr virus (EBV). This infectious disease can be spread by saliva, and the incubation period for mono is four to eight weeks. Using contaminated items, such as drinking glasses or toothbrushes, can spread the infection.