mono incubation period adults
1 Epstein-Barr virus (EBV) is a contagious infection that causes infectious mononucleosis. 2  The illness is spread by casual contact, usually via saliva. 3  Mono has an incubation period of 4 to 6 weeks. The illness is spread by casual contact, usually via saliva. 2  Mono has an incubation period of 4 to 6 weeks. 3  The vast majority of adults have antibodies against EBV, meaning they have been infected with the virus and are immune to mono.