Mononucleosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Epstein-Barr virus, frequently referred to as EBV, is a member of the herpesvirus family and one of the most common human viruses.
Pathophysiology
Epstein-Barr virus, frequently referred to as EBV, is a member of the herpesvirus family that targets oro-pharyngeal epithelium and B cells. Transmission of the EBV through the air or blood does not normally occur. The incubation period, or the time from infection to appearance of symptoms, ranges from 4 to 6 weeks. Persons with infectious mononucleosis may be able to spread the infection to others for a period of weeks. However, no special precautions or isolation procedures are recommended, since the virus is also found frequently in the saliva of healthy people. In fact, many healthy people can carry and spread the virus intermittently for life. These people are usually the primary reservoir for person-to-person transmission. For this reason, transmission of the virus is almost impossible to prevent.
Epidemiology and Demographics
Majority of mononucleosis syndromes are caused by Epstein-Barr virus, and most people become infected with EBV sometime during their lives with an estimated 90%-95% of persons greater than 21 years of age demonstrating antibody to EBV.[1][2] In the United States, the disease occurs most often among older children and young adults; however, in certain socioeconomically depressed areas the infection affects young children who remain asymptomatic. Additionally, the dormant feature combined with long (4 to 6 week) incubation period of the disease, makes epidemiological control of the disease impractical.
Risk Factors
Majority of the population become infected with EBV at sometime during their lives with an estimated 90%-95% of adults demonstrating seropositivity by 21 years of age. Therefore, even individuals exposed to infected contacts have shown to be previously infected with EBV and hence are not at risk for the manifestation of mononucleosis. However, once infected, the patient carries the virus for the rest of their life with the virus typically residing dormantly in the B lymphocytes. Independent infections of mononucleosis may be contracted multiple times, regardless of whether the patient is already carrying the virus dormantly. Periodic reactivation of the virus may occur, during which time the patient is again infectious, but usually without any symptoms of illness. Therefore, in susceptible hosts under the appropriate environmental stressors, reactivation of the virus occurs to cause vague subclinical symptoms or remain mostly asymptomatic and diagnosed only by a positive serologic response. However, its imperative to note that during this phase the virus can spread to others.
Cause
Epstein-Barr virus is ubiquitous across the globe and the strongest causative agent for the manifestation of infectious mononucleosis. Commonly, a person is first exposed to the virus during or after adolescence. Though once deemed "The Kissing Disease", recent research has shown that transmission of mononucleosis not only occurs from intimate contact with infected saliva, but also from contact with the airborne virus.
For more information on the virus, click here
Diagnosis
Symptoms of infectious mononucleosis are fever, sore throat, and swollen lymph glands. Sometimes, a splenomegaly or hepatomegaly may develop. Heart problems or involvement of the central nervous system occurs only rarely, and infectious mononucleosis is almost never fatal. There are no known associations between active EBV infection and problems during pregnancy, such as miscarriages or birth defects. Although the symptoms of infectious mononucleosis usually resolve in 1 or 2 months, EBV remains dormant or latent in a few cells in the throat and blood for the rest of the person's life. Periodically, the virus can reactivate and is commonly found in the saliva of infected persons. This reactivation usually occurs without symptoms of illness.
Treatment
Infectious mononucleosis is generally self-limiting and only symptomatic and/or supportive treatments are used. However, severe tonsillar enlargement may cause life-threatening airway obstruction and therefore, close monitoring of such high-risk patients is essential. Glucocorticoids may be indicated in such cases of severe airway obstruction. Acyclovir has been tried as they decrease oropharyngeal viral shedding. Recently, valacyclovir has shown to lower or eliminate the presence of the Epstein-Barr virus in subjects afflicted with acute mononucleosis, leading to a significant decrease in the severity of symptoms.
Prognosis
- Although the symptoms of infectious mononucleosis usually resolve in 1 or 2 months, EBV remains dormant or latent in a few cells in the throat and blood for the rest of the person's life. Periodically, the virus can reactivate and is commonly found in the saliva of infected persons. This reactivation usually occurs without symptoms of illness.
- EBV also establishes a lifelong dormant infection in some cells of the body's immune system. A late event in a very few carriers of this virus is the emergence of Burkitt's lymphoma and nasopharyngeal carcinoma, two rare cancers that are not normally found in the United States. EBV appears to play an important role in these malignancies, but is probably not the sole cause of disease.
- Symptoms related to infectious mononucleosis caused by EBV infection seldom last for more than 4 months. When such an illness lasts more than 6 months, it is frequently called chronic EBV infection. However, valid laboratory evidence for continued active EBV infection is seldom found in these patients. The illness should be investigated further to determine if it meets the criteria for chronic fatigue syndrome. This process includes ruling out other causes of chronic illness or fatigue.
Resources
References
- ↑ Henle G, Henle W, Clifford P, Diehl V, Kafuko GW, Kirya BG, Klein G, Morrow RH, Munube GM, Pike P, Tukei PM, Ziegler JL (1969). "Antibodies to Epstein-Barr virus in Burkitt's lymphoma and control groups". Journal of the National Cancer Institute. 43 (5): 1147–57. PMID 5353242. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Pereira MS, Blake JM, Macrae AD (1969). "EB virus antibody at different ages". British Medical Journal. 4 (5682): 526–7. PMC 1630375. PMID 4902364. Unknown parameter
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