Mononucleosis history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Lakshmi Gopalakrishnan, M.B.B.S. [2]
Overview
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.
Symptoms
Initial Prodrome
- Common symptoms include:
- Fever: varies from mild to severe, but is seen in nearly all cases.
- Tender and enlarged/swollen lymph node, particularly the posterior cervical lymph nodes.
- Sore throat: white patches on the tonsils and back of the throat are often seen
- Muscle weakness and sometime extreme fatigue
- Some patients also display:
- Petechial hemorrhage
- Abdominal pain- a possible symptom of a potentially fatal rupture of the spleen.[1]
- Myalgia
- Headache
- Loss of appetite
- Depression
- Skin rash
- Diarrhea
- Dizziness or disorientation
- Uncontrolled shaking at times
- Unable to swallow due to enlarged tonsils
- Dry cough
Dormant Infection
- After an initial prodrome of 1-2 weeks, the fatigue of infectious mononucleosis often lasts from 1-2 months. The virus can remain dormant in the B cells indefinitely after symptoms have disappeared, and resurface at a later date. Many people exposed to the Epstein-Barr virus do not show symptoms of the disease, but carry the virus. This is especially true in children, in whom infection seldom causes more than a very mild cold which often goes undiagnosed. Children are typically just carriers of the disease. This feature, along with mono's long (4 to 6 week) incubation period, makes epidemiological control of the disease impractical. About 6% of people who have had infectious mononucleosis will relapse.
Recovery
- Usually, the longer the infected person experiences the symptoms, the more the infection weakens the person's immune system, and hence the longer time is required to recover.
- Cyclical reactivation of the virus, although rare in healthy people, is often a sign of immunological abnormalities in the small subset of organic disease patients in which the virus is active or reactivated.
Other diseases with similar presentation
- Although all cases of mononucleosis are caused by the EBV, cytomegalovirus can produce a similar illness, usually with less throat pain. Due to the presence of the atypical lymphocytes on the blood smear in both conditions, some physicians confusingly used to include both infections under the diagnosis of "mononucleosis," though EBV is by definition the infection that must be present for this illness.
- Symptoms similar to those of mononucleosis can be caused by adenovirus, acute HIV infection and the protozoan Toxoplasma gondii.
Atypical presentations
- In small children, the course of the disease is frequently asymptomatic. The course of the disease can also be chronic. Some patients suffer fever, tiredness, abnormal fatigue, depression, lethargy, and chronic lymph node swelling, for months or years. This variant of mononucleosis has been referred to as chronic EBV syndrome or chronic fatigue syndrome, although the most recent medical studies have discounted the link between chronic EBV infection and chronic fatigue syndrome. In case of a weakening of the immune system, a reactivation of the Epstein-Barr Virus is possible; in CFS there is evidence of immune activation also.
- Although studies conducted by the CDC and others have discounted a link between EBV and CFS, some patients anecdotally report that chronic fatigue lasting for years after mono is part of a CFS. This confusion seems to lie in the nature of the link (note any association does not prove or disprove causality) and possible misapprehension as to the syndromic nature of CFS. Current studies suggest there is an association between infectious mononucleosis and CFS [2]. "Chronic fatigue states" appear to occur in 10% of those who contract mononucleosis[3] Some confusion here may be due to the use of a new, broadened revision of the CFS research criteria, which has been criticised as overly inclusive. Although chronic fatigue may then be a rather common side effect of infectious mononucleosis, it should be noted that CFS is more than "chronic fatigue", requiring at least four other symptoms, and a number of findings have been published which are not typical of EBV infection, although some complications may be shared. Additionally some CFS patients do not describe fatigue as their worst problem.
- Perhaps a majority of chronic post infectious "fatigue states" appear not to be caused by a chronic viral infection, but be triggered by the acute infection. Direct and indirect evidence of persistent viral infection has been found in CFS, for example in muscle and via detection of an unusually low molecular weight RNase L enzyme, although the commonality and significance of such findings is disputed. Hickie et al contend that mononucleosis appears to cause a hit and run injury to the brain in the early stages of the acute phase, thereby causing the chronic fatigue state. This would explain why in mononucleosis, fatigue very often lingers for months after the Epstein Barr Virus has been controlled by the immune system. However, it has also been noted in several (although altogether rare) cases that the only "symptom" displayed by a mononucleosis sufferer is elevated moods and higher energy levels, virtually the opposite of CFS and comparable to hypomania. Just how infectious mononucleosis changes the brain and causes fatigue (or lack thereof) in certain individuals remains to be seen. Such a mechanism may include activation of microglia in the brain of some individuals during the acute infection, thereby causing a slowly dissipating fatigue
References
- ↑ Chapman AL, Watkin R, Ellis CJ (2002). "Abdominal pain in acute infectious mononucleosis". BMJ. 324 (7338): 660–1. doi:10.1136/bmj.324.7338.660. PMID 11895827.
- ↑ Hickie I, Davenport T, Wakefield D, Vollmer-Conna U, Cameron B, Vernon SD, Reeves WC, Lloyd A; Dubbo Infection Outcomes Study Group. Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study. BMJ. 2006 Sep 16;333(7568):575
- ↑ Hickie I, Davenport T, Wakefield D, Vollmer-Conna U, Cameron B, Vernon SD, Reeves WC, Lloyd A; Dubbo Infection Outcomes Study Group. Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study. BMJ. 2006 Sep 16;333(7568):575