Postexposure Prophylaxis Against Varicella-Zoster Virus Infection Among Recipients of Hematopoietic Stem Cell Transplant: Unresolved Issues

Management of a major varicella zoster exposure in a pediatric oncology population

Management of the exposure of pediatric oncology patients to varicella zoster virus (VZV) is controversial. We report the exposure of 56 patients to a single child with chicken pox at a pediatric cancer housing facility and describe our strategic approach for their management. We reviewed the immune and clinical status of 56 children with cancer receiving ongoing treatment at Memorial Sloan Kettering Cancer Center (MSK) who, while living at a pediatric cancer housing facility, were exposed to the index patient. The management of patients exposed included: (1) determination of immune status, (2) availability of vaccination history or VZV disease prophylaxis, (3) exposure status and subsequent isolation during the period of incubation, and (4) VZV disease prophylaxis. In addition to the 56 patients exposed to the index case, eight children with cancer treated at other facilities and 11 healthy siblings living in the facility were exposed. Of the 56 MSK patients, 21 were classified as immunosuppressed and received varicella zoster immune globulin (human), intravenous standard immune globulin, or acyclovir based on serostatus and immune function. The cohort was followed for 4 weeks after the exposure and no secondary infections were diagnosed. We performed a risk assessment and created a management plan to control and prevent further exposure and development of disease. No secondary cases developed. This strategic approach could serve as a model for the management of VZV exposure for other pediatric oncology centers.

Varicella zoster virus in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the diagnosis, prevention, and management of varicella zoster virus (VZV) in the pre- and post-transplant period. Primary varicella is an uncommon complication post-solid-organ transplant (SOT), except among pediatric transplant patients and those seronegative for VZV. As the majority of SOT recipients are seropositive for VZV, herpes zoster (HZ) occurs frequently following SOT, particularly among recipients who are older (≥65 years of age) and those receiving more intensive immunosuppression. Transplant providers should aware of the increased risk for HZ-related complications such as dissemination, organ-specific involvement, and post-herpetic neuralgia. Treatment for localized zoster is primarily given as oral regimens, but those with more complicated presentations or those at risk for dissemination should be treated initially with IV therapy. Available antiviral prophylaxis regimens and vaccination strategies for varicella and HZ among these immunosuppressed patients remain a mainstay for prevention in the pre-and post-transplant periods. Finally, we discuss important approaches to addressing post-exposure prophylaxis and infection control practices for those SOT patients with documented VZV infections.

Prevention of Infections in Patients with Hematological Malignancies

Infection is a major complication of patients with hematological malignancies. Prophylaxis is a key element in the management of these patients, and is composed by two main components: infection control measures and antimicrobial chemoprophylaxis. Infection control measures are safe, but not always effective. Antimicrobial prophylaxis is usually effective but may increase resistance rates, toxicity, and cost. Therefore, a careful evaluation of the actual risk for infection, the pathogens that predominate in a particular setting, and the periods at risk are important in order to define the most appropriate strategy. In this chapter we review the most important parameters to assess the risk on an individual basis, and the evidences and recommendations supporting infection control measures and antimicrobial prophylaxis against bacteria, fungi, viruses, and parasites.

Chicken pox infection in patients undergoing chemotherapy: A retrospective analysis from a tertiary care center in India

There is paucity of data on the incidence, severity and management of chicken pox in patients receiving active chemotherapy for cancer. From October 2010 to October 2011, patients were included in this study if they developed a chicken pox infection during their chemotherapy. The details of patients' cancer diagnosis and treatment along with clinical and epidemiological data of the chicken pox infections were assessed from a prospectively maintained database. Twenty-four patients had a chicken pox infection while receiving chemotherapy and/or radiotherapy. The median age of the patients was 21 years, and two-thirds of the patients had solid tumor malignancies. Overall, eight (33%) patients had complications, six (25%) patients had febrile neutropenia, four (17%) had diarrhea/mucositis, and four (17%) had pneumonia. The median time for recovery of the infection and complications in the patients was 9.5 days (5-29 days), whereas for neutropenic patients, it was 6.5 days (3-14 days). The median time for recovery from chicken pox infections in neutropenic patients was 10 days (5-21 days), compared with 8.5 days (0-29 days) in non-neutropenic patients (P=0.84). The median time for recovery from infections was 8.5 days in patients with comorbidities (N=4), which was the same for patients with no comorbidities. The clinical presentation and complication rates of chicken pox in cancer patients, who were on active chemotherapy, are similar to the normal population. The recovery from a varicella infection and complications may be delayed in patients with neutropenia. The varicella infection causes a therapy delay in 70% of patients. Aggressive antiviral therapy, supportive care and isolation of the index cases remain the backbone of treatment.

Live virus vaccines in transplantation: friend or foe?

Solid organ and hematopoietic stem cell transplant recipients may be exposed to diseases which may be prevented through live attenuated virus vaccines (LAVV). Because of their immunosuppression, these diseases can lead to severe complications in transplant recipients. Despite increasing evidence regarding the safety and effectiveness of certain LAVV, these vaccines are still contraindicated for immunocompromised patients, such as transplant recipients. We review the available studies on LAVV, such as varicella zoster, measles-mumps-rubella, influenza, yellow fever, polio, and Japanese encephalitis vaccines in transplant patients. We discuss the current recommendations and the potential risks, as well as the expected benefits of LAVV immunization in this population.

An Outbreak of Varicella with Likely Breakthrough Disease in a Population of Pediatric Cancer Patients

Background.

Varicella is highly contagious, and immunocompromised patients are at increased risk of severe illness, including disseminated disease, pneumonia, and encephalitis. We describe an outbreak of varicella with likely breakthrough disease in a population of pediatric cancer patients in October 2004.

Setting.

A 250-bed tertiary care pediatric facility with a 33-bed oncology unit, outpatient clinics, and affiliated group housing and schoolroom spaces.

Methods.

We defined varicella as an acute illness with a maculopapulovesicular rash, without other apparent cause. We defined breakthrough disease as varicella with onset more than 42 days after vaccination. Cancer patients were considered to be nonimmune if serologic test results were negative for varicella-zoster virus. Family members were considered to be nonimmune if they had no history of infection with wild-type varicella-zoster virus or of varicella vaccination.

Results.

In a period of approximately 16 days, varicella was detected in 7 children (the index case, 5 secondary cases, and 1 tertiary case). Of the 7 identified cases, 4 appeared to be cases of breakthrough disease in previously vaccinated children. The outbreak resulted in the exposure of 82 families at a pediatric group housing facility; 28 children at the schoolroom; and 77 patients, 150 family members, and 9 staff members at 3 outpatient clinics.

Conclusions.

This outbreak highlights the important role that breakthrough varicella can play in healthcare centers with affiliated group housing. Formal recommendations on the management of exposed individuals who have been vaccinated should be made in such settings, especially if immunocompromised hosts are present.

Prevention of Infections in Patients with Hematological Malignancies

Infection is a frequent complication and a leading cause of morbidity and mortality in patients with hematological malignancies. Problems associated with the management of infections in these patients include difficulties in early diagnosis because the clinical signs of infection are subtle, the low performance of diagnostic tests, and suboptimal response to treatment because recovery of host defenses is a key factor for resolution of infection. Preventing these infections relies on infection control measures and antimicrobial chemoprophylaxis. While infection control measures are safe (but not always effective), the use of antimicrobial agents for prophylaxis of infection is not devoid of problems. Its wide use may increase the possibility of the development of resistance, select for resistant organisms, and increase toxicity and cost. Therefore, any attempt to administer an antimicrobial agent should be accompanied by a reflection of the potential benefits and risks of prophylaxis.

Varicella-zoster immunization in pediatric liver transplant recipients: safe and immunogenic

Varicella can have a severe course in immunosuppressed patients. Although prevention is fundamental, live-attenuated varicella-zoster (VZV) vaccine is not currently recommended in transplant recipients. Our aims were to (1) evaluate VZV immunity in pediatric liver transplant (LT) recipients; (2) immunize (two doses) seronegative patients post-LT; (3) monitor vaccine safety, (4) assess B and T cell vaccine responses. All patients followed at the Swiss National Pediatric LT Center were approached and 77/79 (97.5%) were enrolled (median age 7.8 years). Vaccine safety was monitored by standardized diary cards and phone calls. VZV-specific serology and CD4(+) T cells were assessed before and after immunization. Thirty-nine patients (51.1%) were seronegative including 14 children immunized pre-LT. Thirty-six of 39 seronegative patients were immunized post-LT (median 3.0 years post LT). Local (54.8%) and systemic (64.5%) reactions were mild and transient. The frequency of VZV-specific CD4(+) T cells and antibody titers increased significantly (respectively from 0.085% to 0.16%, p = 0.04 and 21.0 to 1134.5 IU/L, p < 0.001). All children reached seroprotective titers and 31/32 (97%) patients assessed remained seroprotected at follow-up (median 1.7 years). No breakthrough disease was reported during follow-up (median 4.1 years). Thereby, VZV vaccine appears to be safe, immunogenic and provide protection against disease in pediatric LT patients.

Molecular diagnosis and management of viral infections in hematopoietic stem cell transplant recipients

Viral infections after allogeneic hematopoietic stem cell transplantation (HSCT) are important complications associated with high morbidity and mortality. In this setting, reactivations of persisting latent viral pathogens from donor and/or recipient cells play a central role whereas the sterile environment of transplant units renders new infections less likely. The viruses currently regarded as most relevant in the HSCT setting include particularly the herpes virus family--specifically cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV-6)--as well as human adenoviruses (AdVs) and the polyoma virus BK (BKV). Timely detection and monitoring of virus copy numbers are prerequisites for successful preemptive treatment approaches. Pre- and post-transplant surveillance by sensitive and quantitative molecular methods has therefore become an essential part of the diagnostic routine. In this review, we discuss diagnostic aspects and the clinical management of the most important viral infections in HSCT recipients, with a focus on pediatric patients.

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.

Nosocomial infections in patients with cancer

Nosocomial infections are those that become evident 48 h or more after a patient is admitted for treatment in a hospital or in another health-care setting. These infections cause substantial morbidity and mortality in patients who are immunosuppressed. Over the past few decades, understanding of host vulnerability has improved and more rigorous management and infection-control practices have been adopted for treating susceptible populations. Despite efforts, outbreaks continue to occur. In this Review, we outline current knowledge of the incidence and microbiology of various nosocomial infections in patients with cancer-a large, immunosuppressed population.

Management of HSV, VZV and EBV infections in patients with hematological malignancies and after SCT: guidelines from the Second European Conference on Infections in Leukemia

These guidelines on the management of HSV, VZV and EBV infection in patients with hematological malignancies and after SCT were prepared by the European Conference on Infections in Leukemia following a predefined methodology. A PubMed search was conducted using the appropriate key words to identify studies pertinent to management of HSV, VZV and EBV infections. References of relevant articles and abstracts from recent hematology and SCT scientific meetings were also reviewed. Prospective and retrospective studies identified from the data sources were evaluated, and all data deemed relevant were included in this analysis. The clinical and scientific background was described and discussed, and the quality of evidence and level of recommendation were graded according to the Centers for Disease Control criteria.

Viral Infections in Patients with Hematological Malignancies

Viral infections are important causes of morbidity and mortality for patients with a hematological malignancy. However, the true incidence and consequences of viral infections for these patients who undergo conventional nontransplant therapy are poorly defined. The difference in incidence and outcome of viral infections among patient groups is wide, but dependent upon the intensity and duration of T-cell–mediated immune suppression. Infections caused by cytomegalovirus (CMV), herpes simplex virus (HSV), varicella-zoster virus (VZV), respiratory syncytial virus (RSV), parainfluenza viruses and influenza viruses have been intensely studied, yet newly recognized aspects of these viral infections including late CMV infection; the emergence of new viral pathogens (human herpesvirus-6, BK virus, adenovirus, and human metapneumovirus); the development of molecular diagnostic techniques, and the potential of new agents for viral prophylaxis (maribavir), or preemptive therapy (valganciclovir) form the basis of this review. Well-designed prospective studies are needed to better clarify the spectrum of these viral infections and develop effective prevention and treatment strategies. Yet the increased use of agents like alemtuzumab that induce profound T-cell depletion demands that we develop a better understanding of viral infections that occur in patients with hematological malignancy who receive nontransplant therapy.

New agents for the prevention of opportunistic infections in haematopoietic stem cell transplant recipients

Over the past three decades, autologous and allogeneic haematopoietic stem cell transplants (HSCTs) have become effective treatments for a variety of malignant and nonmalignant conditions. Patients who undergo HSCT receive high doses of chemotherapy and/or radiation that induce a prolonged period of profound immunodeficiency, placing them at high risk for infection from a panoply of opportunistic organisms. Although supportive treatment for these patients has markedly improved, 10-20% of allogeneic HSCT recipients will ultimately succumb to infection. Joint guidelines to prevent opportunistic infection were released in 2000 by the Centers for Disease Control, the Infectious Diseases Society of America, and the American Society of Blood and Marrow Transplantation; however, treatment decisions for these patients are often based on limited studies or depend on institution-specific transplant protocols and antibiotic resistance patterns. This paper will discuss new agents for preventing bacterial, fungal and viral infections in HSCT recipients.