|Mononucleosis, or mono, is a common illness usually caused by the Ebstein Barr virus. It typically infects teenagers and young adults, but also occurs in younger children, who have a much milder illness that is often not recognized as mono. Symptoms of mono consist of a high fever, sore throat, swollen tonsils with pus on them, fatigue, an enlarged spleen, and swollen glands that may be tender. Symptoms usually last for only one to two weeks, although the fatigue can last much longer.
Mono can be diagnosed by a 'monospot' blood test and by doing a blood count which will show atypical lymphocytes. However these tests may not be positive if done too early in the course of the infection, so most doctors will wait at least a week before doing these blood tests. It is also possible to test for antibodies in blood against the Ebstein Barr virus to see if there has been a recent or past infection.
There is no treatment for mononucleosis and most people get over it without problems. Rare complications include developing a ruptured spleen or an inflamed liver. To prevent an enlarged spleen from rupturing, children who have had mono are advised to avoid contact sports for at least two months after symptoms go away.
Mono is spread by having contact with the respiratory secretions, usually saliva, of someone who has mono. Symptoms usually do not develop until one to two months after being exposed to the virus. Infection with the Ebstein Barr virus is lifelong, although it usually does not cause any future problems. Mono is also rarely caused by other viruses, including the cytomegalovirus.