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Infectious mononucleosis (IMN) is caused by infection
with Ebstein Barr virus (EBV). This virus enters through the pharyngeal
epithelium and replicates in B-lymphocytes causing them to proliferate.
Atypcial mononuclear cells appear in the blood and represent T-lymphocytes
reacting to the presence of infected B-lymphocytes. The virus maintains
a low level of replication throughout life. The spleen and lymph nodes
become intensely infiltrated with mononuclear cells.
EBV is transmitted by saliva and droplet infection
(airborne) with an incubation period of 2 weeks.
Symptoms and clinical picture of mononucleosis
The disease most commonly occurs in young adults and presents with
fever, headache, sore throat. Pharyngitis, often the most prominent
sign, can be accompanied by enlargement of the tonsils with an exudate
resembling that of streptococcal pharyngitis. Petechiae (tiny bleeding spots) may occur
in the soft palate.
A generalized lymph gland enlargement (particularly involving the posterior
neck lymph glands) and an enlargement of the spleen are common. They
are tender, symmetric but not fixed in place. Mild hepatitis is common.
A morbilliform or papular rash, usually on the arms or trunk,
develops in about 5% of cases. Most patients treated with ampicillin
develop a macular rash. Erythema nodosum and erythema multiforme have
also been described.
Other diseases related to EBV infection
- Burkitt's lymphoma
- Nasopharyngeal carcinoma
- X-linked combined variable immunodeficiency
- Lymphoid interstitial pneumonia in children with AIDS.
Diagnosis of mononucleosis
Atypical lymphocytes are seen in the blood film.
Paul ? Bunnel and monospot tests are used to detect heterophil antibodies
and are usually positive by the second week. Specific EBV IgM antibodies
indicate a recent infection by the virus.
Treatment of mononucleosis
The disease may resolve alone in healthy subjects.
Steroids (prednisolone) is advised when the condition is prolonged or
accompanied by complications.
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