Acyclovir therapy of chickenpox in immunosuppressed children--a collaborative study

Case Report: Neonatal Varicella Acquired From Maternal Zoster

The incidence of neonatal varicella has decreased dramatically since the introduction of the varicella vaccination. Although the varicella zoster virus is often associated with a mild infection, it may cause severe morbidity and mortality, particularly in the neonatal period and immunocompromised hosts. We report a case of neonatal varicella acquired from maternal zoster in a mother on biological immunosuppressive therapy. Following the diagnosis, the baby improved on antiviral therapy without any neurological sequelae. This case highlights the limited published data on neonatal varicella following herpes zoster reactivation to inform practice. This includes the role of varicella zoster immunoglobulin in neonates exposed to maternal zoster, the degree of trans-placental immunity and optimum antiviral dosing and duration.

The Influence of Cyclosporin Immunosuppression on the Efficacy of Famciclovir or Valaciclovir Chemotherapy Studied in a Murine Herpes Simplex Virus Type 1 Infection Model

Mice with or without immunosuppression by cyclosporin (Cy) were inoculated with herpes simplex virus type 1 in the ear pinna. Without immunosuppression, 20% of the mice died; clinical signs resolved in survivors and infectious virus was cleared by 7 to 10 days post-inoculation (p.i.). With Cy, mortality was 50%, clinical signs increased and infectious virus persisted. Mice were treated with either valaciclovir (VACV) or famciclovir (FCV) from days 1–5 or 5–10 p.i. and both compounds moderated the disease, but only FCV led to rapid restoration of body weight and complete protection from mortality. Resolution of clinical signs was more marked with immunosuppression. On cessation of VACV therapy, infectious virus recurred on individual days. Without immunosuppression, recurrence was detected in neural tissues only, but with Cy, infectious virus also recurred in skin. No recurrences of infectious virus were observed in any FCV-treated mice.

Varicella zoster virus infection

Infection with varicella zoster virus (VZV) causes varicella (chickenpox), which can be severe in immunocompromised individuals, infants and adults. Primary infection is followed by latency in ganglionic neurons. During this period, no virus particles are produced and no obvious neuronal damage occurs. Reactivation of the virus leads to virus replication, which causes zoster (shingles) in tissues innervated by the involved neurons, inflammation and cell death - a process that can lead to persistent radicular pain (postherpetic neuralgia). The pathogenesis of postherpetic neuralgia is unknown and it is difficult to treat. Furthermore, other zoster complications can develop, including myelitis, cranial nerve palsies, meningitis, stroke (vasculopathy), retinitis, and gastroenterological infections such as ulcers, pancreatitis and hepatitis. VZV is the only human herpesvirus for which highly effective vaccines are available. After varicella or vaccination, both wild-type and vaccine-type VZV establish latency, and long-term immunity to varicella develops. However, immunity does not protect against reactivation. Thus, two vaccines are used: one to prevent varicella and one to prevent zoster. In this Primer we discuss the pathogenesis, diagnosis, treatment, and prevention of VZV infections, with an emphasis on the molecular events that regulate these diseases. For an illustrated summary of this Primer, visit: http://go.nature.com/14xVI1.

Ocular herpes: the pathophysiology, management and treatment of herpetic eye diseases

Herpesviruses are a prominent cause of human viral disease, second only to the cold and influenza viruses. Most herpesvirus infections are mild or asymptomatic. However, when the virus invades the eye, a number of pathologies can develop and its associated sequelae have become a considerable source of ocular morbidity. The most common culprits of herpetic eye disease are the herpes simplex virus (HSV), varicella zoster virus (VZV), and cytomegalovirus (CMV). While primary infection can produce ocular disease, the most destructive manifestations tend to arise from recurrent infection. These recurrent infections can wreck devastating effects and lead to irreversible vision loss accompanied by a decreased quality of life, increased healthcare usage, and significant cost burden. Unfortunately, no method currently exists to eradicate herpesviruses from the body after infection. Treatment and management of herpes-related eye conditions continue to revolve around antiviral drugs, although corticosteroids, interferons, and other newer therapies may also be appropriate depending on the disease presentation. Ultimately, the advent of effective vaccines will be crucial to preventing herpesvirus diseases altogether and cutting the incidence of ocular complications.

Varicella zoster: an update on current treatment options and future perspectives

INTRODUCTION

Varicella zoster virus is a highly contagious virus that causes a primary infection known as varicella (chickenpox) that may reactivate years later to cause herpes zoster (HZ or shingles). After shingles heal, patients may develop post-herpetic neuralgia (PHN), neuropathic pain syndrome that can cause significant suffering for years and is often refractory to treatment.

AREAS COVERED

The wide range of treatment and management options for varicella, HZ and PHN are reviewed and discussed. PubMed was the database used for the literature search.

EXPERT OPINION

Antiviral therapy effectively treats acute varicella and HZ. However, PHN is still difficult to manage, especially with the numerous treatment measures that do not work consistently in all patients. The best approach is to prevent the complication from occurring in the first place by preventing HZ with the HZ vaccine, which have decreased the burden of illness caused by VZ and the incidence of HZ. Unlike the varicella vaccine, the uptake for the HZ vaccine is very low and thereby more patients over the age of 50 years should be encouraged to receive the vaccine to reduce the risk of developing HZ. Initiating treatment with gabapentin and antiviral concomitantly as soon as the rash develops may reduce the severity of complications but there is a lack of data showing these medications preventing the development of PHN.

Varicella zoster virus infections in Canadian children in the prevaccine era: A hospital-based study

OBJECTIVE

To describe the clinical course of children admitted for varicella zoster virus (VZV) infections to a pediatric hospital before the release of VZV vaccine in Canada.

DESIGN

Retrospective case series.

SETTING

Tertiary pediatric hospital. Population studied was children aged 18 years or younger admitted to hospital between 1983 and 1992 who were discharged with a diagnosis of varicella or zoster. Of the 201 children who were identified, 36 were excluded, leaving 165 for analysis.

RESULTS

There was a male:female ratio of 1.5:1 and a median age of 5.3 years (range two weeks to 18 years). The group included those who were previously healthy (70, 42.4%), immunocompromised (60, 36.4%), and those with nonimmunocompromising conditions (35, 21.2%). Comparison of immunocompetent and immunocompromised children revealed that complication of VZV infection was a more common reason for admission among the former (86 of 105, 81.9%, P<0.001), whereas treatment with acyclovir to limit dissemination was the most common reason in the latter (53 of 60, 88.3%, P<0.001). Skin and soft tissue infections were the most common complications in immunocompetent children (36 of 98) and those younger than five years (26 of 53), whereas pulmonary complications predominated among immunocompromised patients (eight of 98) and neurological complications in five- to 10-year-olds (16 of 36). Only one death (0.6%) occurred in an immunocompetent patient. Group A beta-hemolytic streptococci and Staphylococcus aureus caused equal numbers of secondary infections (92% of all isolates).

CONCLUSIONS

Complications of VZV infections and secondary prophylactic antiviral treatment of immunocompromised children explain the majority of hospitalizations in this institution, and can be monitored after VZV vaccine introduction. Complications vary significantly with underlying healthy status and age.

Preventing varicella in children with malignancies: what is the evidence?

PURPOSE OF REVIEW

The prevention of varicella in children with cancer is generally agreed to be an important goal, because of their elevated risk of varicella zoster virus (VZV)-associated morbidity and mortality. However, there is a lack of consensus on the best means of achieving this. Here, we review the existing evidence in relation to postexposure prophylaxis against varicella in this group and summarize data regarding the role of active vaccination.

RECENT FINDINGS

Death from varicella during treatment for cancer is now rare, but VZV disease and its prevention remain significant problems in paediatric oncology practice. Measures to reduce VZV exposure amongst seronegative individuals are often neglected. When exposure is known to have occurred, early administration of varicella zoster immune globulin (VZIG) is generally protective against severe and complicated varicella. However, many centres in the UK and Japan use an oral antiviral agent, aciclovir, in place of VZIG. Published evidence for the efficacy of aciclovir as postexposure prophylaxis (PEP) relates mostly to healthy children, with no controlled studies in the immunocompromised.

SUMMARY

Good evidence already supports the administration of varicella vaccine to healthy susceptible family contacts of children with malignancy, but not to patients themselves. Further data are urgently needed to inform the choice of PEP against VZV in the immunocompromised.

The pediatrician and medical care of the child with cancer

The child's pediatrician is an important resource for families regarding a host of issues such as infections, complications and side effects of chemotherapy, school issues, and psychosocial stressors that are common in families of children with life-threatening illness. This article provides guidance for caring for children with malignancies in the primary care setting.

Clinical manifestations of varicella-zoster virus infection

Infections by VZV, the virus that causes chickenpox and herpes zoster, usually are diagnosed by the classic clinical presentations. In immunocompromised patients, however, the atypical presentation can make the diagnosis more challenging. Although varicella typically follows an uncomplicated course in children, adults and immunocompromised patients can develop complications involving several organs; some complications may be fatal. Prevention of disease with the vaccine is ideal. When varicella or zoster infection does occur, proper treatment should be initiated, depending on the age and immune status of the patient.

Antiviral therapy for varicella and herpes zoster

Varicella-zoster virus (VZV) causes 2 clinical illnesses, varicella (chickenpox) and herpes zoster (shingles). The purpose of this review is to describe the role of antiviral therapy in the treatment of VZV infections in healthy and immunocompromised children. Acyclovir is the drug of choice for varicella and herpes zoster. The route of administration may be intravenous or oral, depending on the immunocompetence of the host. The clinical impact of acyclovir therapy is related directly to its use early in the clinical course and to the likely susceptibility of the patient to severe or life-threatening VZV infection. Patients who have the most clinical benefit are otherwise healthy adolescents with varicella infection and high-risk populations of immunocompromised children who have varicella or herpes zoster. The morbidity and mortality of VZV infections are reduced substantially by initiating acyclovir treatment early in the course of the disease.

Varicella in a pediatric heart transplant population on nonsteroid maintenance immunosuppression

OBJECTIVE

Varicella-zoster virus has been reported to produce serious, often life-threatening, disease in immunosuppressed patients with a variety of diagnoses. The impact of this virus on the young child after heart transplantation has not been reported.

METHODS

We reviewed the charts of 28 children who were <10 years of age at heart transplantation and had at least 1 year of follow-up. The median follow-up period was 7 years (1.4-13.0 years). All were seronegative for varicella-zoster virus before transplantation. Fourteen (50%) developed varicella at a median time posttransplantation of 3.3 years. The first 7 were admitted for intravenous acyclovir for 3 days followed by oral acyclovir for 7 days. The last 7 were treated as outpatients with oral valacyclovir for 7 days (n = 6) or with oral acyclovir for 10 days (n = 1).

RESULTS

Intravenous and oral regimens both were well tolerated and were without complications. No patient was receiving steroids at the time that they developed their initial episode of varicella. One patient was receiving steroids for therapy of posttransplantation lymphoproliferative disease when she developed recurrent varicella or generalized zoster. No episodes of rejection were attributed to the varicella-zoster virus infection. There were no episodes of localized zoster. All patients experienced seroconversion from undetectable to detectable antibody titers early after varicella, and 12 of the 14 patients continued to have persistent detectable titers in late follow-up. Two of the 14 who received chemotherapy or enhanced immunosuppression after retransplantation transiently lost detectable varicella-zoster virus antibodies but currently have detectable titers.

CONCLUSIONS

Primary varicella-zoster infection was well tolerated in our young pediatric heart transplant recipients, with no serious complications. We now reserve inpatient/intravenous therapy for those who are unable to tolerate oral medications or those who are receiving enhanced immunosuppression.

Controlled trial of acyclovir for chickenpox evaluating time of initiation and duration of therapy and viral resistance

BACKGROUND

Chickenpox is prevalent in the US despite the availability of an effective vaccine. Acyclovir treatment is limited by concerns about efficacy if given after the first day of rash and by concerns about induction of viral resistance.

OBJECTIVE

Evaluate initiation and duration of acyclovir treatment of chickenpox and its effect on viral resistance.

STUDY DESIGN

Randomized, placebo-controlled, double blind trial in immunocompetent patients who were stratified by age at enrollment (children, 2 to 11 years; adolescents, > or = 12 to 18 years; adults, > or = 19 years) and duration of rash (< or = 24 h vs. >24 to 48 h). Lesions were staged, counted and cultured; temperatures and symptoms were recorded daily.

INTERVENTION

Subjects presenting within 24 h of rash onset (Group A) were randomly assigned to 5 or 7 days of oral acyclovir treatment, 80 mg/kg/day up to a maximum of 3,200 mg/day in four divided doses. Subjects whose rash was >24 to 48 h old were randomized to receive 5 days of acyclovir treatment beginning on the first (Group B1) or second study day (Group B2). Matching placebos were used to ensure that subjects uniformly received 28 doses of study compound.

RESULTS

Of the 177 subjects recruited Group A patients who were treated on the first day of rash had the greatest number of significantly shortened event times with 5 days of therapy being equivalent to 7 days. There also were some shorter times to events for Group B1 patients who began therapy on the second day of rash vs. Group B2 patients who started acyclovir on the third. These included: time to maximum lesion formation (adolescents, P = 0.007; children, P = 0.03); 50% healing in adolescents (P = 0.005); and residual facial lesions in adults (P = 0.047). The probability of viral shedding was significantly reduced for Group A subjects vs. Group B1 subjects (P = 0.006). Viruses shed during therapy remained susceptible to acyclovir and retained normal thymidine kinase function.

CONCLUSIONS

Immunocompetent children, adolescents and adults with chickenpox displayed a gradation in their clinical responses to acyclovir that correlated with the time from onset of rash to initiation of therapy. Five days of therapy is sufficient because a 7-day course provided no additional benefit. The susceptibility to acyclovir of viruses shed during treatment did not change; however, the effect of therapy on resistance of latent virus was not assessed.

Pediatric oncology nursing: providing care through decades of change

Pediatric oncology nursing practice has evolved over the years as new technology and trends in health care have precipitated change. Three pediatric oncology nursing leaders share their perspectives on nursing practice as it relates to treatment of a child with leukemia during four different points in time. Their comments illustrate the challenges, resources, and rewards. Their reflections, combined with a survey of the literature over the past half a century, show the dramatic impact of advances in supportive care on the practice of caring for a child with cancer. It is also evident that as the cure rate has increased, so have the efforts to improve quality of life. What has transcended time is the delivery of consistent and compassionate care, the education of patients and families, and the dedication to advocacy and support.

Management of varicella-zoster virus infections in children

The introduction of varicella vaccine for immunization of healthy children is expected to have a gradual impact on the incidence of VZV infections in the population but antiviral therapy remains an important intervention in clinical practice. The efficacy of aciclovir for treatment of primary and recurrent VZV infections in children has reduced the morbidity and mortality of these illnesses in immunocompromised children dramatically. Oral aciclovir is an effective and useful for the management of varicella in healthy children and adolescents.

Assessment of acyclovir intraindividual pharmacokinetic variability during continuous hemofiltration, continuous hemodiafiltration, and continuous hemodialysis

The use of intravenous acyclovir can be particularly complicated in pediatric patients with evolving renal impairment, because of intraindividual pharmacokinetic variability linked to the patient's clinical condition. The objective of this study was to use therapeutic drug monitoring data to assess acyclovir intraindividual pharmacokinetic variability during several types of renal replacement therapy. Bayesian adaptive control of acyclovir dosage regimen was performed in a pediatric patient with bone marrow transplant who developed severe renal impairment. Acyclovir pharmacokinetic parameter values corresponding to the different techniques and periods of renal replacement therapy were estimated using USCPACK PC Clinical Programs and therapeutic drug monitoring data. Results showed a wide intraindividual pharmacokinetic variability during CAVH, CAVHDF, and CVVHD, reflecting not only the performance of each dialysis technique but also the difficulty in making use of each one. The acyclovir elimination rate constant was higher during CVVHD compared to CAVH or CAVHDF. Bayesian method appears to be valuable in assessing intraindividual pharmacokinetic variability, as it allows the clinician to deal with sparse routine patient data.

Varicella zoster virus

Because of its ability to produce two clinically distinct disease entities (chickenpox and shingles), varicella zoster virus (VZV) is an unusual etiologic agent. Although in the past viral exanthems were mostly only of academic interest to the practitioner, the development of antiviral agents and the newly approved varicella (OKA) vaccine have increased the clinical significance. Also, with the increasing seroprevalence of HIV infection, more patients will be stricken with zoster (at a younger age) and disseminated varicella. In this review, the history, incidence, pathogenesis, clinical manifestations, and treatment options (of VZV infection and postherpetic neuralgia) will be discussed.

High-dose acyclovir prophylaxis reduces cytomegalovirus disease in liver transplant patients

Cytomegalovirus (CMV) is still a major pathogen in liver transplantation (LTX). The clinical efficacy of prophylactic high-dose acyclovir therapy (800 mg qid) was assessed for the prevention of CMV infection and disease in liver recipients. Fifty-five patients were enrolled in a prospective, randomised, double-blind and placebo-controlled trial; 28 on acyclovir vs. 27 on placebo. The therapy was given for 12 weeks. The patients were followed for 24 weeks. CMV infection was diagnosed in 60% (16 on acyclovir, 17 on placebo) and CMV disease developed in 38% (7 on acyclovir, 14 on placebo) of the patients. The total mortality was 27% (6 on acyclovir, 10 on placebo). Acyclovir delayed 32% of the CMV infections and prevented 59% of the CMV disease cases which occurred in the placebo cohort. The time to CMV disease was significantly prolonged in patients on acyclovir as compared to patients on placebo (P=0.013). Adverse events included neurotoxicity which occurred in 5 cases in the acyclovir, but none in the placebo arm, and nephrotoxicity which was detected in 6 patients in the acyclovir and 5 in the placebo arm, respectively. We conclude that acyclovir prophylaxis significantly reduced the incidence of CMV disease, and delayed the onset of CMV infection in liver transplant patients.

Current pharmacological approaches to the therapy of varicella zoster virus infections: a guide to treatment

Varicella zoster virus (VZV), a member of the herpesvirus family, is responsible for both primary (varicella, chickenpox) as well as reactivation (zoster, shingles) infections. In immunocompetent patients, the course of varicella is generally benign. For varicella zoster, post-herpetic neuralgia is the most common complication. In immunocompromised patients (particularly those with AIDS), transplant recipients and cancer patients, VZV infections can be life-threatening. For these patients and also for immunocompetent patients at risk such as pregnant women or premature infants, the current treatment of choice is based on either intravenous or oral aciclovir (acyclovir). The low oral bioavailability of aciclovir, as well as the emergence of drug-resistant virus strains, have stimulated efforts towards the development of new compounds for the treatment of individuals with VZV infections. Among these new compounds, penciclovir, its oral prodrug form famciclovir and the oral pro-drug form of aciclovir (valaciclovir), rank among the most promising. As with aciclovir itself, all of these drugs are dependent on the virus-encoded thymidine kinase (TK) for their intracellular activation (phosphorylation), and, upon conversion to their triphosphate form, they act as inhibitors/alternative substrate of the viral DNA polymerase. Therefore, cross-resistance to these drugs may be expected for those virus mutants that are TK-deficient and thus resistant to aciclovir. Other classes of nucleoside analogues dependent for their phosphorylation on the viral TK that have been pursued for the treatment of VZV infections include sorivudine, brivudine, fialuridine, fiacitabine and netivudine. Among oxetanocins, which are partially dependent on viral TK, lobucavir is now under clinical evaluation. Foscarnet, which does not require any previous metabolism to interact with the viral DNA polymerase, is used in the clinic when TK-deficient VZV mutants emerge during aciclovir treatment. TK-deficient mutants are also sensitive to the acyclic nucleoside phosphonates (i.e. [s]-1-[3-hydroxy-2-phosphonylmethoxypropyl]cytosine; HPMPC); these agents do not depend on the virus-encoded TK for their phosphorylation but depend on cellular enzymes for conversion to their diphosphoryl derivatives which then inhibit viral DNA synthesis. Vaccination for VZV has now come of age. It is recommended for healthy children, patients with leukaemia, and patients receiving immunosuppressive therapy or those with chronic diseases. The protection induced by the vaccine seems, to some extent, to include zoster and associated neuralgia. Passive immuniatin based on specific immunoglobulins does not effectively prevent VZV infection and is therefore restricted to high risk individuals (i.e. immunocompromised children and pregnant women).

Sequential use of intravenous and oral acyclovir in the therapy of varicella in immunocompromised children

BACKGROUND

Immunocompromised children are at risk for disseminated varicella infections. Standard management involves hospitalization and intravenous acyclovir for 7 to 10 days. This approach is expensive, is inconvenient and may not be necessary. We undertook a pilot study to assess the safety and efficacy of an alternative approach that utilized a combination of intravenous (i.v.) followed by oral (p.o) acyclovir in a cohort of immunocompromised children.

METHODS

The cohort consisted of 26 immunocompromised children between the ages of 1.5 and 12.7 years (mean, 6.3). Therapy was commenced with i.v. acyclovir (1500 mg/m2/day in 3 divided doses). Concurrent management included holding or reducing immunosuppressive therapy (by 50%) and administering varicella-zoster immunoglobulin in 69% (11 of 16) of cases where exposure to chickenpox was recognized. Patients were eligible to switch to p.o therapy after receiving a minimum of 48 h of i.v. acyclovir therapy provided they were afebrile; had no new lesions for 24 h; had no internal organ involvement and were able to tolerate oral medications. Patients were observed in hospital for a further 24 h and then discharged provided they remained well. Oral acyclovir was continued for a total of 7 to 10 days (i.v. plus p.o).

RESULTS

Of the 26 patients 25 were successfully switched from i.v. to p.o after 4.1 +/- 1.2 days (mean +/- SD) (range, 2.3 to 6) Children had fever for a mean of 2.0 +/- 1.6 days (range, 0 to 5) and developed new lesions for 2.9 +/- 0.7 days (range, 2 to 4). All 25 patients switched to p.o therapy had resolution of their disease and no patient required resumption of i.v. therapy.

CONCLUSIONS

The sequential use of i.v. followed by p.o acyclovir is feasible in the treatment of varicella in immunocompromised children and results in a reduction in duration of intravenous therapy and hospitalization.

Antiviral prophylaxis and treatment in chickenpox. A review prepared for the UK Advisory Group on Chickenpox on behalf of the British Society for the Study of Infection

Prophylactic intervention with varicella-zoster immunoglobulin early in the incubation period can prevent or attenuate the disease manifestations of varicella in susceptible contacts at high risk from this infection. Detailed guidelines are issued in the UK Department of Health publication on Immunization against Infectious Disease. Sensitive immunoassays are available for investigation of antibody status and subclinical seroconversion. Live attenuated varicella vaccine, which has been used successfully post-exposure as well as electively elsewhere, is at present not generally available in the UK. Effective protocols for prophylaxis against varicella with the antiviral agent aciclovir are not yet established. The nucleoside analogue aciclovir (syn: acyclovir, Zovirax) is effective in inhibiting replication of VZV when given at a dosage higher than that required for treatment of HSV, and is currently the only available and approved treatment for varicella in the U.K. Intravenous aciclovir therapy for 5-10 days is effective for varicella in neonates and the immunocompromised, and for varicella pneumonia or other complications in adults and children, if begun early. Oral aciclovir is only effective if begun with 24 h of onset of rash. With that proviso. it is recommended for treatment of varicella in otherwise healthy adults and adolescents, but not for routine use in children under 13 years of age unless they are sibling contacts or have other medical conditions. Aciclovir has a high therapeutic index and good safety profile, but caution is advised with use in pregnancy.

Varicella zoster infection in the immunocompromised child

PURPOSE

To describe varicella zoster virus infection in the immunocompromised child and provide guidelines to decrease the risk of infection and complications for these children.

POPULATION

Children infected with varicella zoster virus, particularly those with a compromised immune system.

CONCLUSIONS

Varicella zoster virus infection can have serious consequences for children with malignancies and infection with the human immunodeficiency virus, as well as children on chronic steroid therapy.

PRACTICE IMPLICATIONS

The advanced practice nurse often is responsible for identifying those children at increased risk for VZV infection and its complications and for planning and implementing interventions to decrease the risks to the immunocompromised child.

Review of 26 years' hospital admissions for chickenpox in North London

The epidemiology of chickenpox admissions to an Infectious Diseases Unit was studied over 26 years. Risk factors, markers of disease severity, and complications were analysed in patients admitted during the last 5 years. Some 613 patients were admitted with chickenpox over three 5-year periods between 1968 and 1993. There was a 2.23-fold increase in the number of adults admitted from home between the first and last period. Patients of European origin showed a three-fold increase. The mean age of adults rose from 26.2 to 34.3 years. Some 23% of adults had varicella pneumonitis. Smokers were six times more susceptible to pneumonitis than were non-smokers. Adult asthmatics were not at increased risk, whereas 42% of asthmatic children had chest complications. Seventeen of the 18 immunocompromised patients had a relatively uncomplicated course. Of the children, 32% had secondary skin infections, with no excess complications among those with eczema. Thrombocytopenia and elevated aspartate transaminases were four times and twice, more frequent in adults than children, respectively. These features occurred mostly in males. The male-to-female admission ratio was 2:1 in adults, and 1.2:1 in children. Males in both age groups showed a trend to more severe disease and more primary complications than did females. Our data showed an increase in adult chickenpox admissions. We have identified asthma as a risk factor for pulmonary complications in children, but not adults, and male gender as an independent risk factor for severe chickenpox.

Analysis of United Kingdom wild-type strains of varicella-zoster virus: differentiation from the Oka vaccine strain

In Japan and the United States, where vaccination against varicella-zoster virus (VZV) infection with the live attenuated Oka strain of varicella is routine, cases of chickenpox or shingles occurring in vaccinees can be caused by either wild-type or vaccine virus. Differentiating such cases is important epidemiologically and can be achieved only using molecular typing methods. In the United Kingdom, the Oka vaccine is being considered for use in groups at risk of severe primary varicella, such as seronegative immunocompromised patients and women who may be considering pregnancy. In addition, seronegative health workers who may be occupationally exposed to VZV infection might also be offered vaccination. We analysed 249 U.K. wild-type VZV strains, 105 from cases of chickenpox and 144 from shingles cases, to determine whether they could be distinguished from Oka by the genotyping systems used in Japan and the United States. Four polymorphic loci were examined, a Pst 1 restriction site in gene 38, a Bgl 1 restriction site in gene 54, the R5 repeat region, and the R2 repeat region. The results suggest that U.K. strains of VZV are more similar to U.S. strains than to Japanese strains. All the U.K. wild-type viruses were positive for the Pst 1-1 restriction site, unlike Oka, which is negative. However, one of thirty strains was indistinguishable from Oka at all other loci.

Live attenuated varicella vaccine

Varicella-zoster virus (VZV) is a ubiquitous human pathogen that causes varicella, commonly called chicken pox; establishes latency; and reactivates as herpes zoster, referred to as shingles. A live attenuated varicella vaccine, derived from the Oka strain of VZV has clinical efficacy for the prevention of varicella. The vaccine induces persistent immunity to VZV in healthy children and adults. Immunization against VZV also has the potential to lower the risk of reactivation of latent virus. The varicella vaccine may eventually reduce or eliminate herpes zoster, which is a serious problem for elderly and immunocompromised individuals.

Varicella-zoster virus

Varicella-zoster virus (VZV) is a ubiquitous human alphaherpesvirus that causes varicella (chicken pox) and herpes zoster (shingles). Varicella is a common childhood illness, characterized by fever, viremia, and scattered vesicular lesions of the skin. As is characteristic of the alphaherpesviruses, VZV establishes latency in cells of the dorsal root ganglia. Herpes zoster, caused by VZV reactivation, is a localized, painful, vesicular rash involving one or adjacent dermatomes. The incidence of herpes zoster increases with age or immunosuppression. The VZV virion consists of a nucleocapsid surrounding a core that contains the linear, double-stranded DNA genome; a protein tegument separates the capsid from the lipid envelope, which incorporates the major viral glycoproteins. VZV is found in a worldwide geographic distribution but is more prevalent in temperate climates. Primary VZV infection elicits immunoglobulin G (IgG), IgM, and IgA antibodies, which bind to many classes of viral proteins. Virus-specific cellular immunity is critical for controlling viral replication in healthy and immunocompromised patients with primary or recurrent VZV infections. Rapid laboratory confirmation of the diagnosis of varicella or herpes zoster, which can be accomplished by detecting viral proteins or DNA, is important to determine the need for antiviral therapy. Acyclovir is licensed for treatment of varicella and herpes zoster, and acyclovir, valacyclovir, and famciclovir are approved for herpes zoster. Passive antibody prophylaxis with varicella-zoster immune globulin is indicated for susceptible high-risk patients exposed to varicella. A live attenuated varicella vaccine (Oka/Merck strain) is now recommended for routine childhood immunization.

Acyclovir for the prevention and treatment of varicella zoster in children, adolescents and pregnancy

Varicella causes a mild, self-limiting childhood disease that may reactivate years later as shingles. In immunocompromised patients with altered cell mediated immunity, and rarely in healthy individuals, varicella results in a life-threatening infection. The antiviral drug, acyclovir, substantially reduces the mortality and risk of severe disease in these groups of patients. Early commencement of acyclovir is recommended for children with both varicella and altered cell mediated immunity, newborns during the first 2 weeks of life, preterm infants in the neonatal nursery, and severe varicella or shingles (including ocular zoster) in any patient, as well as during pregnancy. Acyclovir may be considered in children with serious cardiopulmonary disease or chronic skin disorders where varicella may exacerbate the underlying disease or increase the risk of secondary bacterial sepsis. Acyclovir, however, is not recommended for healthy individuals without severe disease, as a prophylactic agent against varicella, for asthmatics receiving aerosolized or low-dose oral steroids and/or as treatment of the post-varicella syndromes. When acyclovir is prescribed it should be given intravenously to those with severe disease, those at risk of dissemination and in children younger than 2 years of age.

The frequency and consequences of varicella exposure and varicella infection in children receiving maintenance therapy for acute lymphoblastic leukemia

PURPOSE

The frequency and cost of varicella and varicella exposure were determined in children receiving maintenance chemotherapy for acute lymphocytic leukemia, and the cost of a preventative strategy using the varicella vaccine was estimated.

PATIENTS AND METHODS

Retrospective analysis of clinic and hospital records for 472 children at 12 sites who were receiving maintenance chemotherapy on Protocol 105 of the Childrens Cancer Group.

RESULTS

During a mean maintenance period of 2 1/2 years there were 120 exposures to varicella among susceptible children (10/100 patient-years). During the same period there were 60 cases of varicella (4.6/100 patient-years). Half of the cases of varicella occurred without a known exposure. Exposures and varicella resulted in significant omission or delay in chemotherapy. Total medical charges for varicella-related events were $492,000 ($470 per varicella exposure; $7,450 per case of varicella). A proposed preventative strategy using varicella vaccine after 6 months of maintenance therapy would theoretically reduce varicella-related charges by 80%.

CONCLUSIONS

Varicella exposure and varicella are common in this patient population. The use of varicella vaccine during the early maintenance period should be considered to prevent these events. This strategy is likely to be safe, and will save significant medical charges, drug omission, disease-related morbidity, hospitalization, and work and school disruption.

Varicella in immunocompetent children in the first two years of life: role of treatment with oral acyclovir. Italian Acyclovir-Chickenpox Study Group

An open multicenter study has been carried out to evaluate efficacy and tolerability of oral acyclovir in the treatment of varicella in immunocompetent patients in the first two years of life. Fifty-three children aged 3-24 months received acyclovir at 80 mg/Kg/day in four divided doses for 4 to 6 days; 24 of them were treated in the first 24 hours following disease onset, while the remaining 29 patients were enrolled within 48 hours. The assessment of evolution of disease signs and symptoms showed a rapid resolution of fever, itching and other constitutional symptoms, with interruption of vesicle formation and acceleration of cutaneous healing processes. No statistically significant differences have been demonstrated as to disease progression between patients treated in the first 24 hours, when compared with subjects receiving acyclovir in the following 24 hours. Acyclovir confirmed its excellent clinical and laboratory safety profile. By acting favorably on both the duration and severity of disease signs and symptoms, acyclovir treatment should be recommended in young children and infants with varicella, since a higher incidence of severe and complicated disease has been observed in these patient groups.