Varicella-Zoster Virus: Atypical Presentations and Unusual Complications
John W. Gnann
0
1
Jr.
0
1
0
Financial support: GlaxoSmithKline (honoraria and research funding). abama at Birmingham, Div. of Infectious Diseases
,
845 S. 19th St., BBRB 220, Birmingham, AL 35294-2170
1
University of Alabama at Birmingham and Birmingham VA Medical Center
,
Birmingham, Alabama
Varicella-zoster virus (VZV) is the etiologic agent of varicella (primary infection) and herpes zoster (reactivation of latent infection). Although varicella is most often a relatively benign and self-limited childhood illness, the disease can be associated with a variety of serious and potentially lethal complications in both immunocompetent and immunocompromised persons. One complication of varicella that appears to be increasing in frequency is serious bacterial soft tissue infections caused by group A streptococci. Issues related to management of varicella become especially complex when varicella involves pregnant women or susceptible neonates. Herpes zoster can be associated with a variety of neurologic complications, including a syndrome of delayed contralateral hemiparesis. Neurologic complications of herpes zoster, including chronic encephalitis, occur with increased frequency in AIDS patients. VZV retinitis is a potentially sight-threatening complication that occurs in both immunocompetent and immunocompromised persons. Current knowledge regarding pathogenesis and antiviral therapy is reviewed.
-
Varicella-zoster virus (VZV) causes two clinically distinct
diseases. Primary infection results in varicella (chickenpox), a
common and extremely contagious acute infection that occurs in
epidemics among preschool and school-aged children, is
characterized by generalized vesicular rash. Like other
a-herpesviruses, VZV establishes latency in neural tissue following
primary infection. Reactivation of latent VZV from dorsal root
ganglia results in herpes zoster (shingles), a localized cutaneous
eruption accompanied by neuralgic pain that occurs most
commonly in older persons. The typical clinical presentations of
varicella and herpes zoster are distinctive and readily recognized
by most experienced clinicians. However, atypical clinical
presentations and uncommon complications of these diseases can
pose diagnostic and therapeutic challenges. This review will
address some less common manifestations of VZV infection
that can occur in otherwise healthy immunocompetent persons
and in special populations.
Varicella
Pneumonitis as a complication of varicella is rare in healthy
children but occurs with increased frequency in
immunocompromised persons of all ages and in immunocompetent
adolescents and adults [1, 2]. Among otherwise healthy adults with
varicella, 2.7%16.3% will have radiographic evidence of VZV
pneumonitis, but only about one-third of those with abnormal
chest radiographs will have respiratory symptoms [36]. As
discussed below, varicella pneumonia appears to be more
frequent and more severe in pregnant women [7]. The onset of
respiratory symptoms (including cough, dyspnea, and
sometimes hemoptysis) usually occurs within a few days of
development of the varicella rash. The chest radiograph reveals a
diffuse interstitial nodular infiltrate [2, 8]. Prior to the
availability of antiviral therapy, mortality rates of up to 30% were
reported for varicella pneumonia. However, with the advent of
antiviral treatment and intensive supportive care, the mortality
rate is now probably less than 10%. Although intravenous
acyclovir has not been evaluated in controlled trials for treatment
of varicella pneumonia, abundant clinical experience and
anecdotal reports indicate the drug is effective in this setting
[911].
Neurologic Complications
The incidence of neurologic complications associated with
varicella is estimated to be 13 per 10,000 cases [12]. The central
nervous system (CNS) manifestations that occur most
frequently with varicella are cerebellar ataxia and encephalitis
[1315]. Other rare neurologic complications include transverse
myelitis, aseptic meningitis, and Guillain-Barre syndrome
[1618]. Few data exist to help define the role of antiviral
therapy for neurologic complications of varicella.
Varicella with cerebellar ataxia. Symptomatic cerebellar
ataxia occurs in about 1 in 4000 varicella cases [12]. The
pathogenesis of this syndrome is incompletely understood, partly
because the illness is rarely fatal and few pathologic studies
have been reported. Possible mechanisms are direct viral
infection of the cerebellum or a parainfectious immunologically
mediated demyelinating process. VZV-specific antibodies and
antigens have been found in cerebrospinal fluid (CSF) of
patients with varicella-associated cerebellar ataxia, suggesting that
VZV replicates within the CNS [1921].
Ataxia may develop from several days before to 2 weeks after
the onset of varicella, although the neurologic symptoms most
often occur simultaneously with rash [16]. Ataxia is usually
accompanied by vomiting, headache, and lethargy; nuchal
r (...truncated)