Infectious Mononucleosis
What is infectious mononucleosis?
What causes infectious mononucleosis? Who gets infectious mononucleosis? How does EBV cause disease? What are the common findings? How is infectious mononucleosis diagnosed? How is infectious mononucleosis treated? What are the complications? How can infectious mononucleosis be prevented? What research is being done? What is infectious mononucleosis?Infectious mononucleosis, also known as "kissing disease," mononucleosis, or, sometimes, just "mono," is an illness characterized by many complaints, but primarily by fever, fatigue, tiredness, enlarged lymph nodes ("lymphadenopathy"), and a sore throat. This disease was originally described in the late nineteenth century as "glandular fever," and it is still known by that name in Europe.
What causes infectious mononucleosis?The Epstein-Barr Virus (EBV), a DNA virus that is a member of the herpesvirus family of viruses, causes approximately 90% of cases of infectious mononucleosis. Approximately 10% of cases of infectious mononucleosis-like illnesses are caused by primary infection with cytomegalovirus, Toxoplasma gondii, Human Immunodeficiency Virus (HIV), adenovirus, viral hepatitis, and rubella virus.
Who gets infectious mononucleosis?EBV is found throughout the world and infects more than 98% of the world's population. In underdeveloped and developing countries, and in socio-economically disadvantaged populations of the United States, up to 100% of children are infected with EBV by 2 to 4 years of age. In more affluent populations in the United States, initial EBV infection also occurs more often in young children, but approximately 50% of infection occurs during adolescence and young adulthood. Because initial EBV infection in young children tends to be without any symptoms, most cases of what is diagnosed as infectious mononucleosis occurs in adolescence and young adulthood, even though EBV infection is more common in young children.
How does EBV cause disease?EBV and the other causes of infectious mononucleosis are transmitted from person-to-person by direct contact or by contaminated secretions of the nose and the mouth. EBV then causes infection in the throat that results in the symptoms of a sore throat and swollen lymph nodes in the neck. The virus then spreads to the white blood cells in the blood stream and causes enlarged lymph nodes in other places throughout the body. The virus, like all other herpesviruses, establishes lifelong infection in the affected person. However, this lifelong infection generally does not cause any symptoms.
What are the common findings?six weeks. Initial infection in young children is often without any symptoms, or with only mild symptoms. Primary infection in approximately 50% of adolescents and adults appears as fever, fatigue and tiredness, swollen lymph nodes, a sore throat, and, sometimes, an enlarged spleen and liver. Symptoms typically develop over several days and persist for a variable period of days, with gradual spontaneous resolution. The total duration of the disease usually is two to three weeks without complications.
How is infectious mononucleosis diagnosed?Initially, infectious mononucleosis can be diagnosed in an adolescent or adult on the basis of the typical symptoms-fever, fatigue and malaise, swollen lymph nodes, and a sore throat. The complete blood count may show an uncommon type of white blood cells ("atypical lymphocytes"), which can suggest infectious mononucleosis. The diagnosis is confirmed by checking for antibodies to the virus. If one of the many other causes of infectious mononucleosis is considered, specific blood tests for those causes are available.
How is infectious mononucleosis treated?There is no specific treatment for infectious mononucleosis. Antibiotics usually are not helpful because the primary cause, EBV, is a virus. Viruses cannot be treated with antibiotics. Antiviral therapy with acyclovir has been shown to decrease viral growth and shedding of EBV from the mouth, but this treatment does not affect the severity of symptoms, the duration of the clinical course, or the eventual outcome.
What are the complications?The great majority of patients with infectious mononucleosis recover uneventfully without complications. Some chronic conditions have been suggested to be associated with infectious mononucleosis, but this has not been proved. At present, there is no evidence to support the association of EBV infection with chronic fatigue syndrome or chronic immune dysfunction.
How can infectious mononucleosis be prevented?There is no vaccine for EBV or the other causes of infectious mononucleosis. There is very little information on how to prevent it. Outbreaks are uncommon. Minimizing exposure to the oral secretions of infected persons can prevent the spread of infectious mononucleosis. Most healthy adults excrete EBV from the mouth periodically throughout their lives, with approximately 20% of the healthy adult population excreting EBV at any given time.
What research is being done?There is much research into the molecular events that are important in the control of EBV after the initial infection resolves. There is interest in developing a vaccine because almost everybody is infected with EBV in childhood and because of the association of EBV with several types of cancer.
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