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Third stage
Medicine
Lec-3
د
.
حسين
1/1/2014
Infectious mononucleosis (IM) and Epstein-Barr virus (EBV)
EBV is a gamma herpes virus.
In developing countries, subclinical infection in childhood is virtually universal.
In developed countries, primary infection may be delayed until early adult life.
The virus is acquired from asymptomatic excreters via saliva, by droplet infection, or by
kissing.
EBV is not highly contagious ,isolation is unnecessary.
IM is an acute viral illness characterised by fever , pharyngitis, cervical
lymphadenopathy, and lymphocytosis.
Whereas ~90% of cases of IM are due to EBV,
5–10% of cases are due to CMV.
CMV is the most common cause of heterophile-negative mononucleosis.
Less common causes ,Toxoplasma, HIV, herpesvirus, hepatitis viruses and drug
reactions.
Clinical features
IM has a prolonged and undetermined incubation period, followed by fever, headache
and malaise, followed by severe pharyngitis, which may include tonsillar exudates, and
non-tender cervical lymphadenopathy.
Palatal petechiae, periorbital oedema, splenomegaly, macular, petechial or erythema
multiforme rashes may occur.
In most cases fever resolves over 2 weeks, and fatigue and other abnormalities settle
over a further few weeks.
IM may present with jaundice ,PUO or complication .
Death is rare but can occur due to
1. Respiratory obstruction.
2. Haemorrhage from splenic rupture or thrombocytopenia.
3. Encephalitis .
Complications
Common
Severe pharyngeal oedema
Antibiotic-induced rash (80-90% with ampicillin)
Prolonged post-viral fatigue (10%)
Hepatitis (80%)
Jaundice (< 10%)
Uncommon
Neurological
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Cranial nerve palsies
Polyneuritis
Transverse myelitis
Meningoencephalitis
Haematological
Haemolytic anaemia
Thrombocytopenia
Renal
Interstitial nephritis
Cardiac
Myocarditis
ECG abnormalities
Pericarditis
Rare
Ruptured spleen
Respiratory obstruction
Agranulocytosis
X-linked lymphoproliferative syndrome
EBV-associated malignancy
Nasopharyngeal carcinoma
Burkitt's lymphoma
Primary CNS lymphoma
Hodgkin's disease
Lymphoproliferative disease in immunocompromised
Diagnosis
Outside the usual age in adolescence and young adulthood is difficult.
In children under 10 years the illness is mild and short-lived, but in adults over 30 years of
age it can be severe and prolonged.
Investigations
Atypical lymphocytes are common in EBV infection but also occur in other causes of IM, HIV
infection, viral hepatitis, mumps and rubella. The most commonly used diagnostic criteria is
the presence of 50% lymphocytes with at least 10% atypical lymphocytes.
A 'heterophile' antibody is present during the acute illness and convalescence, agglutinates
erythrocytes of other species, e.g. sheep and horse.
detected by the classical Paul-Bunnell titration or a more convenient slide test such as the
'Monospot'.
Specific EBV serology (immunofluorescence) can be used to confirm the diagnosis if
necessary.
1-Acute infection is characterised by IgM antibodies against the viral capsid, antibodies to
EBV early antigen and the initial absence of antibodies to EBV nuclear antigen (anti-EBNA).
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2-CNS infections may be diagnosed by detection of viral DNA in cerebrospinal fluid .
Management
largely symptomatic. If a throat culture yields
aβ-haemolytic streptococcus, a course of penicillin should be prescribed. ampicillin or
amoxicillin in this condition commonly causes an itchy macular rash, and should be
avoided .
When pharyngeal oedema is severe, a short course of corticosteroids, e.g.
prednisolone 30 mg daily for 5 days, may help.
Antivirals are not sufficiently active against EBV .
Return to work or school is governed by the patient's physical fitness. contact sports
should be avoided until splenomegaly has completely resolved because of the danger
of splenic rupture.
10% of patients with IM suffer a chronic relapsing syndrome .
Shingles (herpes zoster)
After initial infection VZV persists in latent form in the dorsal root ganglion of sensory
nerves and can reactivate in later life as a localised rash or with other clinical
manifestations.
Commonly seen in the elderly, shingles may also present in younger patients with immune
deficiency.
Chickenpox may be contracted from acase of shingles but not vice versa. It is not clear why
this happens.
Clinical features
Burning discomfort occurs in the affected dermatome, where discrete vesicles appear
3-4 days later, associated with a brief viraemia and can produce distant satellite
'chickenpox' lesions.
Severe disease, a prolonged duration of rash, multiple dermatomal involvement or
recurrence suggests underlying immune deficiency, including HIV.
Thoracic dermatomes are most commonly involved .
Ophthalmic division of the trigeminal nerve is also frequently affected; vesicles may appear
on the cornea and lead to ulceration. This condition can lead to blindness.
Bowel and bladder dysfunction occur with sacral nerve root involvement.
The virus occasionally causes myelitis or encephalitis.
Ramsay Hunt syndrome
Involvement of the Geniculat ganglion causes facial palsy, ipsilateral loss of taste and
buccal ulceration, plus a rash in the external auditory canal. This may be mistaken for Bell's
palsy.
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Post-herpetic neuralgia
Postherpetic neuralgia arises in approximately 20% of patients .Troublesome persistence of
pain for 1-6 months or longer, following healing of the rash. It is more common with
advanced age.
Management and prevention
Aciclovir has been shown to reduce both early- and late-onset pain. new drugs valaciclovir
and famciclovir demonstrate similar or superior efficacy and good safety and tolerability.
Post-herpetic neuralgia requires aggressive analgesia, along with agents such as
amitriptyline or gabapentin .
Capsaicin cream may be helpful.
Acyclovir for chickenpox/shingles
Aciclovir shortens symptoms in chickenpox by an average of 1 day. In shingles aciclovir
reduces pain by 10 days and the risk of post-herpetic neuralgia by 8%. Aciclovir is therefore
cost-effective in shingles but not chickenpox.'
Human VZ immunoglobulin (VZIG) is used to attenuate infection in people who have had
significant contact with VZV, are susceptible to infection (i.e. have no history of chickenpox
or shingles and are negative for serum VZV IgG) and are at risk of severe disease (e.g.
immunocompromised, steroid-treated or pregnant).
Ideally, VZIG should be given within 7 days of exposure, but it may attenuate disease even if
given up to 10 days afterwards.
A zoster vaccine (Zostavax)
Is a live, attenuated vaccine(virus was modified, or weakened, to produce produce
immunity in the body without causing illness). Is exceedingly safe
On March 24, 2011, the Food and Drug Administration (FDA) approved its use for the
prevention of shingles in individuals 50 to 59 years of age, including persons who have
already had an episode of shingles.
should not be given to individuals who have
A weakened immune system
Individuals with active, untreated tuberculosis.
Pregnant women should not receive this vaccine.