 [ Symptoms ] how long is mono contagious [ Disease ] infectious mononucleosis or “mono” is caused by epstein barr virus ebv a member of the herpes virus family it is spread during close physical contact mostly through transmission of saliva that is pretty close earning mono its nickname “kissing disease ” ninety percent to 95 of people in the u s eventually are infected by ebv although not all of them develop full blown mononucleosis people can transmit ebv to other people for six months or longer after recovering from mononucleosis in studies many people continue to have ebv in their saliva for up to 18 months after symptoms of mono have resolved that is why most people who get mononucleosis do not remember being around or kissing someone with mono it is also possible to periodically shed ebv virus in one is saliva throughout life without having symptoms it is not clear if people commonly transmit the virus during these periods fever sore throat fatigue and swollen tonsils and lymph nodes are the usual symptoms of mono the worst of the symptoms go away in one to two weeks but fatigue can last for months vetsika ek expert reviews in molecular medicine 2004 vol 623 pp 1 16 fafi kremer s journal of infectious disease 2005 vol 1916 pp 985 989