Mononucleosis overview

Mononucleosis Microchapters
Home
Patient Information
Overview
Pathophysiology
Epidemiology and Demographics
Risk Factors
Causes
Differentiating Mononucleosis from other Diseases
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Mononucleosis overview On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Mononucleosis overview All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Mononucleosis overview
CDC on Mononucleosis overview
Mononucleosis overview in the news
Blogs on Mononucleosis overview
Directions to Hospitals Treating Mononucleosis
Risk calculators and risk factors for Mononucleosis overview

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. 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

Differential Diagnosis

Acute mononucleosis, acute cytomegalovirus infection and toxoplasma gondii infection have similar clinical presentations. In addition, since their management is much the same, it is not always helpful, or possible, to distinguish between infectious mononucleosis and cytomegalovirus infection. However, in pregnant women, it is imperative to differentiate mononucleosis from toxoplasmosis as toxo is associated with significant consequences in the fetus. Acute HIV infection can also mimic signs similar to those of infectious mononucleosis, and tests should be performed in pregnant women for the same reason as toxoplasmosis.

Natural History, Complications and Prognosis

Fatalities from mononucleosis are extremely rare in developed nations. However, chronic sub-clinical infection may persist secondary to the dormant virus within the B cells. Reactivation of the virus may occur in susceptible hosts under the appropriate environmental stressors. Similar such reactivation or chronic sub-clinical viral activity in susceptible hosts may trigger multiple host autoimmune diseases and cancers secondary to virus predilection to B lymphocytes and its ability to alter both lymphocyte proliferation and lymphocyte antibody production.

History and Symptoms

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.

Physical Examination

The classic initial presentation of mononucleosis include: fever, lymphadenoapthy, pharynigitis, rash and/or periorbital oedema. Occasionally, patients infected with EBV may also display splenomegaly, with subsequent life-threatening complication of splenic rupture and/or hepatomegaly.

Laboratory Findings

In most cases of infectious mononucleosis, the clinical diagnosis can be made from the characteristic triad of fever, pharyngitis, and lymphadenopathy lasting for 1 to 4 weeks.

Other Imaging Studies

Direct and indirect evidence of persistent viral infection long after recovery from acute illness has been found in patients with chronic fatigue syndrome. This is possibly due to the activation of microglia during the acute infection phase in such individuals. Lumbar puncture, EEG, CT scan and/or MRI may help to evaluate such patients with presumable CNS involvement.

Other Diagnostic Studies

Bilateral tender lymphadenopathy, particularly, the posterior posterior cervical lymph nodes are characteristic of mononucleosis. Therefore, lymph node biopsy if done may reveal atypical lymphocytosis.

Medical Therapy

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.

Surgery

Infectious mononucleosis is generally self-limiting and only symptomatic and/or supportive therapy may be required. However, in cases of life-threatening splenic rupture which may occur even without trauma, immediate surgery may be life-saving.

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

CDC Mononucleosis

References

Template:WikiDoc Sources