E. Coli, Mononucleosis, Influenza, Meningitis, Pneumonia and Shingles (herpes zoster) are the most common infectious diseases. Regarding E. Coli, Dr. Stacey Baker, Infectious Disease Physician with Baptist Health South Florida, explains people may get it from contaminated food products. Mononucleosis is also called the kissing disease because it can be easily passed through oral secretions and it’s very common in teens and young people. Influenza alarms people of all ages. Meningitis can be caused by both, bacteria and viruses. It can be very concerning when it happens, the specialist says.