MONONUCLEOSIS
DEFINITION:
A syndrome caused by the Epstein Barr Virus (EBV) resulting in a
sore throat, fever, and fatigue.
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- peak incidence in adolescence (60-80% are seropositive)
- rare in children < 2 years of age
- risk factors:
PATHOGENESIS:
- a member of the herpes group of viruses
- routes of infection:
- primarily via oral secretions
- also parenterally (transfusions, organ transplants)
- sexual transmission
- incubation period: 30-50 days
- enters the body via oral mucosa cells -> targets
B-lymphocytes -> transformed into freely dividing B-cells (the
heterophile antibodies are directed towards these immortilized
cells)
- host responds to the EBV invasion by 2 populations of
T-Cells: Natural Killer Cells (the 'atypical lymphocytes') and
Lymphokines
- the clinical presentation of an EBV infection is primarily
a function of the age-dependent immunological response to the
virus
- poorly contagious with a low secondary attack rate
- immunosuppressed patients who are seropositive often
reactivate the EBV and 60% will shed the virus - other
infectious agents producing a mono-like illness:
- CMV, HIV, toxoplasmosis, hepatitis A, adenovirus,
rubella, mumps, diphtheria, group A beta-hemolytic
streptococcus
CLINICAL FEATURES:
- insidious onset with symptoms lasting 2-4 weeks followed by
a gradual recovery
- sore throat
- fever (39 C)
- fatigue, malaise, poor appetite
- headache
2. Signs
- pharyngitis
- exudative with palatal petechiae
- marked tonsillar enlargement +/- exudates
- lymphadenopathy
- non-tender
- unilateral or bilateral
- anterior and posterior cervical
- also epitrochlear and generalized
- splenomegaly (50%)
- +/- LUQ tenderness
- rubella-like rash (3-15%)
- develops in 80-90% of patients given ampicillin or
amoxicillin
- others
- hepatomegaly (33%)
- jaundice (5%)
- periorbital edema
2. Complications
- Aseptic Meningitis, Encephalitis, Cerebellitis
- Myelitis, Transverse Myelitis
- Guillain-Barre Syndrome, Peripheral Neuropathies, Bell
Palsy
- acute ataxia, chorea, seizures, nuchal rigidity
2. Respiratory
- acute upper airway obstruction (tonsillomegaly or
subglottic edema)
- interstitial pneumonitis
3. Cardiovascular
4. Gastrointestinal
- splenic rupture
- anicteric hepatitis (80%)
- pancreatitis
- parotitis
- Reye Syndrome
5. Genitourinary
6. Hematological
- autoimmune hemolytic anemia - I & II
- thrombocytopenic purpura
- pancytopenia, aplastic anemia
- Hemophagocytic Syndrome
7. Neoplastic
- Lymphoproliferative Syndrome (Duncan Disease)
- Burkitt Lymphoma
- Nasopharyngeal Carinoma
- ? Hodgkin's Lymphoma
INVESTIGATIONS:
- hemolytic anemia (positive Coombs test)
- leukocytosis (with 'atypical lymphocytosis [T-cells])
- neutropenia, thrombocytopenia
2. Serum
- mildly elevated AST, ALT, & bilirubin (anicteric hepatitis)
3. Antibodies
- a + test is pathognomonic
- Paul-Bunnell-Davidsohn test
- Monospot (Agglutination Test)
- the heterophil-antibody response is a function of age and
may be absent in infants & young children (thus a negative
monospot in a child <10 years of age should be followed up
with a specific EBV antibody test
2. Specific EBV
- positive Virus Capsid Antigen (VCA)-IgM
- positive anti-VCA-IgG
- negative Ebstein Barr Nuclear Antigen (EBNA)
MANAGEMENT:
- signs and symptoms resolve over 2-4 weeks followed by a
gradual recovery
- avoid activities that could lead to splenic rupture, i.e.,
contact sports, bike riding, skating, skiing, etc. until the
splenomegaly is no longer detected
2. Medical (for complications)
- indicated for upper airway obstruction due to tonsillar
enlargement
2. Systemic
- indicated for neurolgical and hematological
complications
2. Antibiotics
- use erythromycin or clindamycin for a secondary
infection and avoid ampicillin and amoxil
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