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L7
HHV3
D. Haider
HHV3 (VARICELLA ZOSTER VIRUS):
Varicella-zoster virus (HHV-3) causes a primary infection (varicella, or chickenpox) and a
reactivation disorder (herpes zoster, or shingles). VZV establishes lifelong latency after the
initial infection.
Varicella in adults and immunocompromised persons of any age is associated with greater
morbidity and occasional mortality. Contact and airborne precautions should be used for
hospitalized patients with varicella.
Herpes zoster occurs most often in persons older than 60 years. Up to 4% of persons who have
had one episode of herpes zoster will experience a second episode; recurrence rates are increased
in immunocompromised patients.
Herpes zoster cannot be transmitted by contact with a person who has active herpes zoster
lesions. However, persons lacking VZV immunity may develop varicella from close contact
with viral particles in herpes zoster lesions. Hospitalized patients with herpes zoster must be
placed in contact isolation; airborne isolation is required for patients who are
immunocompromised.
Clinical Features and Diagnosis
• Varicella develops after an incubation period of 10 to 21 days following exposure. Fever,
malaise, and rash (often pruritic) subsequently develop. Classically, the exanthem begins
on the face and trunk and spreads centrifugally to the extremities.
• Oropharyngeal mucosa may also be involved. Characteristic lesions consist of macules,
papules, vesicles, and scabs in different stages of development at the same time
• Most infections resolve within 1 to 2 weeks. Complications, most often in adults, include
pneumonitis, acute cerebellar ataxia, encephalitis, hepatitis, and secondary bacterial skin
infections.
• Nonimmune pregnant women are especially prone to varicella pneumonitis during the
second and third trimesters, and perinatal infection may occur if infection presents
approximately 5 days before and up to 2 days after delivery.
Herpes Zoster
• Herpes zoster presents with pain or paresthesias in a specific dermatome; the
characteristic rash develops several days later ,In order of frequency, the thoracic,
trigeminal, lumbar, and cervical cutaneous dermatomes are most often involved. Lesions
are similar to varicella, and the rash does not cross the midline. Scattered lesions may
occur outside the affected dermatome, more commonly in immunocompromised patients.
• Pain due to acute neuritis and postherpetic neuralgia is the most debilitating complication.
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• Post herpetic neuralgia refers to pain that continues for more than 1 month after resolution
of the rash. More than 50% of cases occur in persons older than 60 years. Herpes zoster
ophthalmicus is a potentially serious sight threatening condition that may develop when
the first branch of the trigeminal nerve is involved
• Involvement of the geniculate ganglion may cause Ramsay Hunt syndrome (pain and
vesicles in the external ear canal, ipsilateral peripheral facial palsy, and altered or absent
taste).
• Other extra cutaneous complications include central nervous system involvement
(meningoencephalitis or encephalitis, transverse myelitis, Guillain-Barre syndrome, and
stroke), visceral disease (pneumonitis and hepatitis), and secondary bacterial skin
infections.
Diagnosis
Diagnosis of varicella is clinical and is based on characteristic skin lesions. The lesions may
sometimes be confused with disseminated HSV or enteroviral infections; direct fluorescent
antibody tests or PCR of samples from active vesicular lesions may be useful in differentiating
the infection. Serologic assays detecting IgG antibodies to VZV confirm both previous infection
and immunity.
Treatment
Acyclovir, valacyclovir, and famciclovir, if started within 72 hours of onset of VZV rash,
accelerate the resolution of lesions, decrease new lesion formation and viral shedding, and lessen
the severity of acute zoster pain.
Valacyclovir and famciclovir also decrease the duration of postherpetic neuralgia. Intravenous
acyclovir is indicated for hospitalized, immunocompromised patients and for patients with
severe neurologic complications. The addition of glucocorticoids to antiviral therapy is
controversial.
Mubark A. Wilkins