Infectious mononucleosis
provided by a.D.A.M., inc.
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definition
an acute viral infection causing high temperature, sore throat, and swollen lymph glands, especially in the neck. It is typically caused by the epstein-barr virus, but can also be caused by the cytomegalovirus (cmv).
Alternative names
mononucleosis - eb; epstein-barr viral syndrome; mono
causes, incidence, and risk factors
mononucleosis-like disease may be caused by the cytomegalovirus (cmv) as well as the classic mononucleosis of the epstein-barr virus (ebv). Both viruses are members of the herpes virus family.
Mononucleosis caused by ebv is the most frequently encountered type and is responsible for approximately 85% of infectious mononucleosis cases. The infection is often transmitted by saliva. While peak incidence occurs in 15- to 17-year-olds, the infection may occur in any age, being most often diagnosed between the ages of 10 and 35.
Infectious mononucleosis may begin slowly with fatigue, malaise, headache, and sore throat. The sore throat becomes progressively worse, often with enlarged tonsils covered with a whitish-yellow fibrinous exudate. The lymph nodes in the neck are frequently enlarged and painful. A pink measles-like rash may occur in approximately 1 out of 10 individuals with mono.
Four out of five patients with mononucleosis who are given ampicillin or amoxicillin for their "throat infection" will develop the rash, but it is significantly darker and denser than the rash in those not given medication. Symptoms of mononucleosis gradually subside over a period of weeks to a month. The disease is generally self-limited.
Risk factors other than age are not known. The incidence in the united states is 2 out of 1,000 in adolescents and young adults. It is significantly lower for the entire u.S. Population. Age of infection varies from country to country. For example, in africa most individuals have been infected by age 3 years, an age at which there are very few symptoms.
Chronic ebv infection may be associated with some types of malignancy. In africa, ebv is associated with burkitt's lymphoma, while in china and among the eskimos, ebv may be associated with cancers of the nose and throat (nasopharyngeal carcinoma). In organ transplant patients it can cause post-transplant lymphoproliferative disease (ptld), a type of lymphoma.
Prevention
infectious mononucleosis can be contagious when in close or intimate contact with an infected person. Since the infection is probably spread by saliva, kissing or other transfer of oral secretions should be avoided.
Symptoms
fever
sore throat
enlarged lymph nodes, especially in the neck and axilla (armpit)
facial swelling
general discomfort, uneasiness, or ill feeling (malaise)
drowsiness
loss of appetite
muscle aches or stiffness
enlarged spleen
rash
less frequently occurring symptoms include:
jaundice (yellow cast to skin)
headache
neck stiffness
sensitivity to light
cough
shortness of breath
chest pain
rapid heart rate
irregular heart rate
nosebleed
hives
fatigue
signs and tests
a physical examination reveals an enlarged liver and (or) enlarged spleen. The liver and spleen may be tender when they are gently pressed (palpation). There may be a skin rash present. Laboratory findings often include such characteristic findings as atypical lymphocytes, which are unusual appearing white blood cells that are seen when the blood is examined under a microscope. This sign may persist for 2 to 8 weeks. Abnormalities of liver function are also characteristic.
Common tests for eb include:
a monospot test (positive for infectious mononucleosis)
epstein-barr virus antigen by immunofluorescence (positive for ebv)
a cbc
shows decreased platelet count
shows atypical lymphocytes
a chemistry panel shows abnormal liver enzyme results
other tests that may reflect changes:
lymphocyte count (may become elevated)
rheumatoid factor (may become temporarily positive)
quantitative immunoglobulins (nephelometry)
leukocyte alkaline phosphatase
ldh isoenzymes
ldh
immunoelectrophoresis - serum
febrile/cold agglutinins
cryoglobulins
coombs' test, direct
blood differential
ast
anti-smooth muscle antibody
aldolase