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.
What is mononucleosis? Mononucleosis, also known as mono, is an infectious disease that is usually caused by the Epstein-Barr virus (a herpes virus). Other viruses can also cause mononucleosis. Mononucleosis is not considered a serious illness, but its symptoms may be severe enough to prevent a person from engaging in normal activities for several weeks.