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 developsseveral 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. 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). Otherextra 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 beconfused 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 theresolution 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.