Mononucleosis or glandular fever or Kissing disease is a kind of infection mostly caused by a kind of virus known as the Epstein-Barr virus (EBV) or the Human Herpesvirus number 4. This infection causes symptoms like fever, sore throat, enlargement of the lymph nodes on the neck, fatigue, and so on; lasting for about 2-4 weeks and may even progress to cause complications like liver or spleen swellings. The signs and symptoms of this infection vary with age.
In kids, this infection may just produce flu-like symptoms or may not produce any symptoms at all.
In teenagers or young adults, this infection commonly produces three major symptoms which include; Fever- mild and lasting about 14 days, Sore throat- severe for 3-5 days and resolves in about 7-10 days, Swollen glands- usually found at the back of the neck and sometimes throughout the body. Other symptoms include; tiredness, headaches, nausea, abdominal pain, etc. These symptoms may disappear after 2-4 weeks but the infected person may continue to feel unwell for several months.
In older adults, this infection is most likely going to progress to liver enlargement and jaundice. Their symptoms are prolonged and more serious than in adolescents.
Epstein-Barr Virus Infection
This virus is a member of the Herpesviridae family of DNA viruses.  Most cases of infectious mononucleosis are caused by this virus. This virus is transmitted mainly through direct contact with an infected person’s saliva through kissing, toothbrush sharing, etc. this is why this infection is usually called the Kissing disease. A large percentage of the population must have been exposed to this virus by the age of 40 but not everyone who has been exposed to the virus gets infected. Just about 40% of exposed adults actually get infected with the virus.