Infectious mononucleosis (IM), also known as mono, kissing disease, or glandular fever, is an infection commonly caused by the Epstein–Barr virus (EBV). Most people are infected by the virus as children, when the disease produces little or no symptoms. In young adults, the disease often results in fever, sore throat, enlarged lymph nodes in the neck, and tiredness. Most people get better in two to four weeks; however, feeling tired may last for months.