User:Cyclonenim/Workbook

This is where I'll copy and paste old, relevent sections which I might try and use in future when I'm majorly reforming an article. —Cyclonenim (talk · contribs · email) 16:49, 3 November 2008 (UTC)

Infecious mononucleosis

Signs and symptoms

• Fever—this varies, but is seen in nearly all cases.
• Enlarged and tender lymph nodes—particularly the posterior cervical lymph nodes.
• Sore throat—White patches on the tonsils and back of the throat are often seen
• Muscle weakness and Mental fatigue (sometimes extreme)

Additional symptoms include:

• Enlarged spleen (splenomegaly, which may lead to rupture) and/or liver (hepatomegaly)
• Petechial hemorrhage
• Abdominal pain - a possible symptom of a potentially fatal rupture of the spleen.
• Aching muscles
• Headache
• Loss of appetite
• Depression
• Diarrhea
• Dizziness or disorientation
• Inability to swallow, due to enlarged tonsils
• Dry cough
• Supra-orbital edema—the eyes become puffy and swollen—may occur in the early stages of 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.

Mononucleosis can cause the spleen to swell. Rupture may occur without trauma, but impact to the spleen is also a factor. Other complications include hepatitis (inflammation of the liver) causing elevation of serum bilirubin (in approximately 40% of patients), jaundice (approximately 5% of cases), and anemia (a deficiency of red blood cells). In rare cases, death may result from severe hepatitis or splenic rupture.

Although most cases of mononucleosis are caused by the E.B. virus, the condition is defined by the clinical presentation and laboratory findings. Cytomegalovirus can produce a similar illness, usually with less throat pain, and also generate atypical lymphocyte proliferation. In recent years, as precise virological and serological studies are more commonly done to identify the actual causative virus, some clinicians have taken to use "mononucleosis" to refer only to the E.B. virus cases. Symptoms similar to those of mononucleosis can also be caused by adenovirus, acute HIV infection and the protozoan Toxoplasma gondii.

Atypical presentations of mononucleosis/EBV infection

In small children, the course of the disease is frequently asymptomatic. Some adult patients suffer fever, tiredness, lassitude (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 (CFS), although CFS is a distinct condition from IM. Still, current studies suggest there is an association between infectious mononucleosis and CFS. 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. "Chronic fatigue states" as defined by the CDC criteria for CFS, appear to occur in 10% of those who contract mononucleosis. Chronic fatigue may then be a rather common side effect of infectious mononucleosis. On the other hand, studies conducted by the CDC and others have discounted a link between EBV and CFS.

Perhaps a majority of chronic post infectious "fatigue states" appear not to be caused by a chronic viral infection, but are 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. 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. Microglia may remain activated or "damaged" for months following infection, thereby causing a slowly dissipating fatigue. Secondary infections can occur. Such infections include mild swelling of the cartilage between the sternum and ribs occurring approximately one month after initial diagnosis.

Diagnosis

Peripheral blood smear (low power) showing lymphocytosis from a 16-year-old male with pharyngitis and positive monospot test.

Laboratory findings usually include an elevated white blood cell count and abnormal liver function tests. The white cell count elevation is predominantly in the lymphocyte portion, and of those the majority is often of the atypical form characteristic of the disease.

Specific tests for EBV include:

• A monospot test (positive for infectious mononucleosis)
• Epstein-Barr virus antigen by immunofluorescence (positive for EBV)
• Epstein-Barr virus antibody titers to help distinguish acute infection from past infection with EBV