Definition
Mononucleosis, often called kissing disease, is an infectious disease that you can get it through kissing. The virus that causes mono is transmitted through saliva, which means you can also get it through a cough or sneeze, or by sharing a glass or food utensils with someone who has mono.
Causes
The Epstein-Barr virus is the most common cause among the viruses that cause mononucleosis. Most adults who have been exposed to the Epstein-Barr virus and have built up antibodies are immune and won't get mononucleosis again.