Influenza A and the virus associated haemophagocytic syndrome: cluster of three cases in children with acute leukaemia

Potential specific therapies in COVID-19

COVID-19 has grown into a global pandemic that has strained healthcare throughout the world. There is a sense of urgency in finding a cure for this deadly virus. In this study, we reviewed the empiric options used in common practice for COVID-19, based on the literature available online, with an emphasis on human experiences with these treatments on severe acute respiratory syndrome-associated coronavirus (SARS-COV-1) and other viruses. Convalescent blood products are the most promising potential treatment for use in COVID-19. The use of chloroquine or hydroxychloroquine (HCQ), remdesivir, and tocilizumab are some of the other promising potential therapies; however, they are yet to be tested in randomized clinical trials (RCTs). The use of lopinavir-ritonavir did not prove beneficial in a large RCT. The use of corticosteroids should be avoided in COVID-19 pneumonia unless used for other indications, based on the suggestion of harm in patients with SARS-COV-1 and Middle Eastern Respiratory Syndrome (MERS) infection. The reviews of this paper are available via the supplemental material section.

Macrophage Activation Syndrome

Hemophagocytic lymphohistiocytosis (HLH), or termed macrophage activation syndrome (MAS) when associated with rheumatic disorders, is a frequently fatal complication of infections, rheumatic disorders, and hematopoietic malignancies. Clinically, HLH/MAS is a life-threatening condition that is usually diagnosed among febrile hospitalized patients (children and adults) who commonly present with unremitting fever and a shock-like multiorgan dysfunction scenario. Laboratory studies reveal pancytopenia, elevated liver enzymes, elevated markers of inflammation (ESR, CRP), hyperferritinemia, and features of coagulopathy. In about 60% of cases, excess hemophagocytosis (macrophages/histiocytes engulfing other hematopoietic cell types) is noted on biopsy specimens from the bone marrow, liver, lymph nodes, and other organs. HLH/MAS has been hypothesized to occur when a threshold level of inflammation has been achieved, and genetic and environmental risk factors are believed to contribute to the hyperinflammatory state. A broad variety of infections, from viruses to fungi to bacteria, have been identified as triggers of HLH/MAS, either in isolation or in addition to an underlying inflammatory disease state. Certain infections, particularly by members of the herpesvirus family, are the most notorious triggers of HLH/MAS. Treatment for infection-triggered MAS requires therapy for both the underlying infection and dampening of the hyperactive immune response.

One-Year Prospective Study of Community Acquired Influenza and Parainfluenza Viral Infections in Hospitalized Egyptian Children with Malignancy: Single Center Experience

BACKGROUND

Respiratory viruses are widespread in the community and easily transmitted to immunocompromised patients.

AIMS

Assess the prevalence of community-acquired respiratory viral infections among children with cancer presenting with clinical picture suggestive of lower respiratory tract infections (LRTIs), and evaluate its risk factors and prognosis.

METHODS

Over a year, 90 hospitalized children with malignancy and LRTIs recruited, subjected to clinical assessment, investigated through hematology panel, blood culture, chest x-ray, CT chest and PCR for influenza A and B, parainfluenza (PIV) types 1 and 3 viruses, and respiratory syncytial virus (RSV), and prospectively followed up for the clinical outcome.

RESULTS

Viral pathogens were identified in 34 patients (37.7%), with a seasonal peak from April to May. The most frequently detected virus was influenza virus [type A (16 cases; 47%), type B (4 cases; 12%)] followed by parainfluenza virus [PIV1 (9 cases; 26%), PIV3 (3 cases; 15%)], and none had RSV. Bacteria were identified in 26 patients, fungi in four, mixed infections [bacterial/viral and bacterial/fungal] in 13, and 36 cases had unidentified etiology. The majority of patients with influenza and parainfluenza infections had hematological malignancy, presented with fever, and had mild self-limited respiratory illness. Five patients with mixed viral and bacterial infection had severe symptoms necessitating ICU admission. Six patients died from infection-related sequelae; two had mixed PIV and Staphylococcal infections.

CONCLUSIONS

Community acquired influenza and parainfluenza infections are common in pediatrics patients with malignancy, either as isolated or mixed viral/bacterial infections. Clinical suspicion is essential as hematological and radiological manifestations are nonspecific. Rapid diagnosis and management are mandatory to improve patients' outcome.

Immunogenicity of a 2009 pandemic influenza virus A H1N1 vaccine, administered simultaneously with the seasonal influenza vaccine, in children receiving chemotherapy

BACKGROUND

No examination of simultaneous vaccination against pandemic H1N1 and the seasonal influenza virus strains, in children with cancer receiving chemotherapy, are yet published. We investigated the immunogenicity of a whole-virion, inactivated, adjuvanted pandemic H1N1, and seasonal influenza vaccines administered simultaneously to children with cancer undergoing chemotherapy.

PROCEDURE

We prospectively enrolled 27 pediatric patients receiving therapy for various types of cancer. All received influenza vaccination once in a seasonal risk period. We checked hemaglutination-inhibition (HAI) antibody titers in the sera of patients before, and 21-28 days after vaccination. Seroprotective titer was defined as an antibody titer ≥ 40, and seroresponse as ≥ 4-fold increase in antibody titers after vaccination.

RESULTS

The pre- and post-vaccination seroprotective rates were H1N1: 33-48%, H3N2: 56-78%, B: 0-15% for seasonal influenza, and for pandemic H1N1: 15-37%. The seroresponse rates for seasonal influenza H1N1, H3N2, and B were 22%, 37%, and 22%, respectively, and 30% for the pandemic H1N1 vaccine.

CONCLUSIONS

Whole-virion, inactivated, adjuvanted vaccine for the pandemic H1N1 Influenza A virus and the seasonal influenza vaccines were found safe and partially immunogenic in children with cancer receiving chemotherapy. The only determinants of responsiveness were lymphocyte count and serum immunoglobulin-G. Only influenza B vaccine elicited significant differences in differences in pre- and post-vaccination seroprotective rates. The response to vaccination for pandemic H1N1 is as effective as other vaccines, however administration of a single vaccine during chemotherapy is more comfortable for pediatric cancer patients.

Safety of high dose trivalent inactivated influenza vaccine in pediatric patients with acute lymphoblastic leukemia

BACKGROUND

Although children with acute lymphoblastic leukemia (ALL) mount immune responses after vaccination with the trivalent influenza vaccine (TIV), these responses are lower compared to controls. Recently, a high dose (HD) TIV was found to increase the level of antibody response in elderly patients compared to the standard dose (SD) TIV. We hypothesized that the HD TIV would be well-tolerated and more immunogenic compared to the SD TIV in pediatric subjects with ALL.

PROCEDURE

This was a randomized, double-blind, phase I safety trial comparing the HD to the SD TIV in children with ALL. Our secondary objective was immunogenicity. Subjects were randomized 2:1 to receive either the HD (60 µg) or the SD (15 µg) TIV. Local and systemic reactions were solicited, hemagglutinin inhibition titers to influenza virus antigens were measured, and monitoring labs were collected prior to and/or after each vaccination.

RESULTS

Fifty subjects were enrolled (34 HD, 16 SD). Mean age was 8.5 years; 63% were male, and 80% were in maintenance therapy. There were no significant differences reported in local or systemic symptoms. No severe adverse events were attributed to vaccination. No significant differences between the HD and SD TIV groups were noted for immune responses.

CONCLUSIONS

No differences were noted between the HD and SD TIV groups for solicited systemic and local reactions. Since this study was not powered for immunogenicity, a phase II trial is needed to determine the immunogenicity of HD versus SD TIV in the pediatric ALL population.

A prospective study of chemotherapy immunologic effects and predictors of humoral influenza vaccine responses in a pediatric oncology cohort

BACKGROUND

Pediatric oncology patients represent a cohort of individuals uniquely at risk of complications from influenza, yet less likely to respond to the vaccine. It is not yet clear how to best protect this vulnerable population.

METHODS

We performed a prospective analysis of 177 pediatric oncology patients to define the predictors of influenza vaccine responses. Each variable was examined over three time points and a repeated measure analysis was performed.

RESULTS

Patients with ALL vaccinated during induction phase had superior influenza vaccine responses than those subjects vaccinated during post-induction or maintenance phases (P=0·0237). Higher aggregate HAI titer responses were associated with a higher baseline B-cell count (P=0·0240), and higher CD4 and CD8 influenza-specific T-cell responses, suggesting prior antigen exposure is a significant contributor. The solid tumor cohort had equivalent responses during all time frames of chemotherapy.

DISCUSSION

The optimal protection from influenza of pediatric patients on chemotherapy should include vaccination, but it is clear that not all patients produce high titers of antibodies after vaccination. This study identified biomarkers that could be used to individualize vaccine approaches. Immunologic predictors might have a role in targeting resources, as B-cell counts predicted of vaccine responses among the patients with ALL.

Influenza vaccination in children being treated with chemotherapy for cancer

BACKGROUND

Influenza infection is a potential cause of severe morbidity in children with cancer; therefore vaccination against influenza is recommended. However, data are conflicting regarding the immune response to influenza vaccination in children with cancer, and the value of vaccination remains unclear.

OBJECTIVES

1. To assess the efficacy of influenza vaccination in stimulating an immunological response in children with cancer during chemotherapy, compared with control groups.2. To assess the efficacy of influenza vaccination in preventing confirmed influenza and influenza-like illness and/or in stimulating immunological response in children with cancer treated with chemotherapy, compared with placebo, no intervention or different dosage schedules.3. To identify the adverse effects associated with influenza vaccines in children with cancer treated with chemotherapy, compared with other control groups.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to 2012) and EMBASE (1980 to 2012) up to August 2012. We also searched reference lists of relevant articles and conference proceedings of the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), the Infectious Diseases Society of America (IDSA), the Multinational Association of Supportive Care in Cancer (MASCC) and the International Society of Paediatric Oncology (SIOP).

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in which the serological response to influenza vaccination of children with cancer was compared with that of control groups. We also considered RCTs and CCTs that compared the effects of influenza vaccination on clinical response and/or immunological response in children with cancer being treated with chemotherapy, compared with placebo, no intervention or different dosage schedules.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed the methodological quality of included studies and extracted the data.

MAIN RESULTS

We included 1 RCT and 9 CCTs (total number of participants = 770). None of the included studies reported clinical outcomes. All included studies reported on influenza immunity and adverse reactions to vaccination. In five studies, immune responses to influenza vaccine were compared in 272 children receiving chemotherapy and 166 children not receiving chemotherapy. In four studies, responses to influenza vaccine were assessed in 236 children receiving chemotherapy compared with responses in 142 healthy children. Measures used to assess immune responses included a four-fold rise in antibody titre after vaccination, development of a haemagglutination inhibition (HI) titre > 32 and pre- and post-vaccination geometric mean titres (GMTs). Immune responses in children receiving chemotherapy were consistently weaker (four-fold rise of 38% to 65%) than those in children who had completed chemotherapy (50% to 86%) and in healthy children (53% to 89%). In terms of adverse effects, 391 paediatric oncology patients received influenza vaccine, and the adverse effects described included mild local reactions and low-grade fever. No life-threatening or persistent adverse effects were reported.

AUTHORS' CONCLUSIONS

Paediatric oncology patients receiving chemotherapy are able to generate an immune response to the influenza vaccine, but it remains unclear whether this immune response protects them from influenza infection or its complications. We are awaiting results from well-designed RCTs addressing the clinical benefit of influenza vaccination in these patients.

A case of novel swine influenza A (H1N1) pneumonia complicated with virus-associated hemophagocytic syndrome

Influenza related to complications such as pneumonia and encephalitis have sporadically been reported. However, influenza A (H1N1)-virus-associated hemophagocytic syndrome (VAHS) has rarely been reported. A 39-year old woman complained of high fever and was referred to us. Chest infiltrations in both lungs and a positive polymerase chain reaction (PCR) for novel swine-origin influenza A (H1N1) in bronchial alveolar lavage fluid (BALF) specimen was confirmed and she was diagnosed with influenza A (H1N1) pneumonia. Pancytopenia was found, and hemophagocytic syndrome (HPS) was diagnosed by bone marrow aspiration. Following intravenous administration of antiflu drug and combination therapy of steroid pulse and erythromycin IV, the patient’s respiratory dysfunction and lab data gradually improved and she was discharged on day 21. Whereas secondary HPS related to viral infections such as Epstein–Barr virus, cytomegalovirus, and human herpesvirus type 6 are commonly seen, H1N1 pneumonia complicated with secondary VAHS is rare.

Protecting pediatric oncology patients from influenza

Influenza is a common respiratory pathogen. Its severity can be unpredictable, but people with chronic illness are at increased risk of severe infection, complications, and death from influenza. This review examines evidence to support various strategies to protect pediatric oncology patients from influenza-related morbidity. Influenza vaccination should be considered standard. Additional evidence-supported measures include antiviral treatment, antiviral prophylaxis, cohorting of patients, and hospital infection control measures. Data from other high-risk populations support the vaccination of family members, double-dose or high-dose vaccination, and the use of barrier methods. These measures have the potential to optimize patient outcomes because there will be fewer treatment interruptions for acute illness. These strategies can also protect patients from prolonged hospitalizations and morbidity related to influenza.

Debate around infection-dependent hemophagocytic syndrome in paediatrics

Background

Hemophagocytic syndrome (HPS) is clinically defined as a combination of fever, liver dysfunction, coagulation abnormalities, pancytopenia, progressive macrophage proliferation throughout the reticuloendothelial system, and cytokine over-production, and may be primary or secondary to infectious, auto-immune, and tumoral diseases. The most consistent association is with viral infections but, as it is still debated whether any micro-organisms are involved in its pathogenesis, we critically appraised the literature concerning HPS and its relationship with infections.

Discussion

Infection-dependent HPS has been widely observed, but there are no data concerning its incidence in children. A better understanding of the pathophysiology of HPS may clarify the interactions between the immune system and the variously implicated potential infectious agents. Epstein-Barr virus (EBV) infection has been prominently associated with HPS, with clonal proliferation and the hyperactivation of EBV-infected T cells. However, a number of other viral, bacterial, fungal, and parasitic infections have been reported in association with HPS. In the case of low-risk HPS, corticosteroids and/or intravenous immunoglobulin or cyclosporine A may be sufficient to control the biological process, but etoposide is recommended as a means of reversing infection-dependent lymphohistiocytic dysregulation in high-risk cases.

Summary

HPS is a potential complication of various infections. A polymerase chain reaction search for infectious agents including EBV, cytomegalovirus and Leishmania is recommended in clinical settings characterised by non-remitting fever, organomegaly, cytopenia and hyperferritinemia.

Is Swine-origin Influenza a Predisposing Factor for Deep Vein Thrombosis?

Herein we report a sixteen-year-old female that developed deep vein thrombosis (DVT) while undergoing treatment for H1N1 pneumonia. To the best of our knowledge this is the first report of H1N1/09 infection complicated by DVT in an adolescent patient with no detected risk factors other than immobilization. Healthcare providers should be aware of the possibility of thrombosis in patients with swine-origin influenza, especially in those with additional risk factors.

Immune response to 2009 pandemic H1N1 influenza virus A monovalent vaccine in children with cancer

PURPOSE

This study investigated the immune response to 2009 pandemic H1N1 influenza monovalent vaccine in children with cancer receiving chemotherapy.

METHODS

We enrolled 25 pediatric patients. Ten patients younger than 10 years old received two vaccinations and the remaining 15 patients older than 10 years old received one. We checked hemagglutination-inhibition (HAI) antibody titers in sera of patients before and 3-4 weeks after vaccination. Seroprotective titer was defined as HAI antibody titer ≥ 40 and seroresponse as ≥ 4-fold increase in HAI antibody titers after vaccination.

RESULTS

The pre- and post-vaccination seroprotective rates were 52% and 72% (P = 0.24). Sixteen (64%) patients were possibly exposed to 2009 pandemic H1N1 influenza previously, and there was significant association between possible exposure and pre-vaccination seroprotective rate (P = 0.03). Post-vaccination seroresponse rate was 32%, and seroresponse was greater in patients without pre-vaccination seroprotective titer than those with pre-vaccination seroprotective titer (50% vs. 15%, P = 0.07). Children with lymphocyte counts above 1,500/µl during vaccination period had better seroresponse than those with lymphocyte counts below 1,500/µl (P = 0.008). Post-vaccination geometric mean titer (GMT) significantly increased in patients younger than 10 years receiving two vaccinations (pre- and post-vaccination GMT were 21.4 and 60.6, respectively; P = 0.025).

CONCLUSIONS

Monovalent vaccine for the 2009 pandemic H1N1 influenza A was found to be partially immunogenic in children with cancer, as evidenced by 32% of seroresponse rate. Immune response can be improved with vaccinations administered to patients whose absolute lymphocyte counts returned to a level of 1,500/µl or higher.

Virus-associated hemophagocytic syndrome as a major contributor to death in patients with 2009 influenza A (H1N1) infection

Introduction

Virus-associated hemophagocytic syndrome (VAHS) is a severe complication of various viral infections often resulting in multiorgan failure and death. The purpose of this study was to describe baseline characteristics, development of VAHS, related treatments and associated mortality rate of consecutive critically ill patients with confirmed 2009 influenza A (H1N1) infection and respiratory failure.

Methods

We conducted a prospective observational study of 25 critically ill patients with 2009 influenza A (H1N1) infection at a single-center intensive care unit in Germany between 5 October 2009 and 4 January 2010. Demographic data, comorbidities, diagnosis of VAHS, illness progression, treatments and survival data were collected. The primary outcome measure was the development of VAHS and related mortality. Secondary outcome variables included duration of mechanical ventilation, support of extracorporeal membrane oxygenation and duration of viral shedding.

Results

VAHS developed in 9 (36%) of 25 critically ill patients with confirmed 2009 influenza A (H1N1) infection, and 8 (89%) of them died. In contrast, the mortality rate in the remaining 16 patients without VAHS was 25% (P = 0.004 for the survival difference in patients with or without VAHS by log-rank analysis). The patients were relatively young (median age, 45 years; interquartile range (IQR), 35 to 56 years of age); however, 18 patients (72%) presented with one or more risk factors for a severe course of illness. All 25 patients received mechanical ventilation for severe acute respiratory distress syndrome and refractory hypoxemia, with a median duration of mechanical ventilation of 19 days (IQR, 13 to 26 days). An additional 17 patients (68%) required extracorporeal membrane oxygenation for a median of 10 days (IQR, 6 to 19 days).

Conclusions

The findings of this study raise the possibility that VAHS may be a frequent complication of severe 2009 influenza A (H1N1) infection and represents an important contributor to multiorgan failure and death.

The efficacy of influenza vaccination in a pediatric oncology population

There is little known about the impact of the timing of influenza vaccine administration on seroconversion in patients on chemotherapy. Recommendations for other vaccines state that the vaccines should be readministered several months after the completion of chemotherapy outside of the stem cell transplant setting. This is not often possible with the influenza vaccine because of its seasonal nature. To examine whether certain times during chemotherapy are more favorable for seroconversion, we examined vaccine responses in a cohort of children on chemotherapy. Pediatric patients on chemotherapy were recruited over the 2006 to 2008 influenza vaccine seasons. Sixty-eight acute lymphoblastic leukemia (ALL), 3 acute myeloid leukemia, and 18 sarcoma patients were evaluated. Clinical and laboratory features were recorded. The hemagglutination inhibition (HAI) assay was used to define serotype-specific responses. Seroconversion rates varied according to the type of chemotherapy during the vaccination period. In some cases, there was a late rise in titer, suggesting that a wild-type infection had occurred, leading to an estimate of vulnerability of this population. In patients with ALL, responses to the vaccine were greater when it was given early in the course of treatment. We conclude that seroconversion rates are well below the rates cited for the general population. The 3 acute myeloid leukemia patients had a particularly poor response to the vaccine. In the case of ALL patients, it may be possible to adjust the timing of the vaccine to optimize the response.

Viral infections associated with haemophagocytic syndrome

Haemophagocytic syndrome (HPS) or haemophagocytic lymphohistiocytosis (HLH) is a rare disease caused by a dysfunction of cytotoxic T cells and NK cells. This T cell/NK cell dysregulation causes an aberrant cytokine release, resulting in proliferation/activation of histiocytes with subsequent haemophagocytosis. Histiocytic infiltration of the reticuloendothelial system results in hepatomegaly, splenomegaly, lymphadenopathy and pancytopenia ultimately leading to multiple organ dysfunctions. Common clinical features include high fevers despite broad spectrum antimicrobials, maculopapular rash, neurological symptoms, coagulopathy and abnormal liver function tests. Haemophagocytic syndrome can be either primary, i.e. due to an underlying genetic defect or secondary, associated with malignancies, autoimmune diseases (also called macrophage activation syndrome) or infections. Infectious triggers are most commonly due to viral infections mainly of the herpes group, with EBV being the most common cause. HPS can be fatal if untreated. Early recognition of the clinical presentation and laboratory abnormalities associated with HPS and prompt initiation of treatment can be life saving. HPS triggered by viral infections generally does not respond to specific antiviral therapy but may be treated with immunosuppressive/immunomodulatory agents and, in refractory cases, with bone marrow transplantation. Copyright © 2010 John Wiley & Sons, Ltd.

Community acquired influenza requiring hospitalization: vaccine status is unrelated to morbidity in children with cancer

BACKGROUND

Community acquired influenza can be severe and there are few data regarding hospitalization for children with cancer and influenza. Association between prior vaccination and infection severity has not been studied, although vaccination is standard practice.

PROCEDURE

Patients with malignancy or prior stem cell transplant (SCT) were identified using a database of children with laboratory confirmed influenza (2000-2005). Other data collected included receipt of vaccine, absolute neutrophil count (ANC) and absolute lymphocyte count (ALC). These were compared with intensive care unit (ICU) stay, respiratory complications and hospital days.

RESULTS

There were 39 patients with laboratory-confirmed influenza with a median age of 6.9 years. Twenty-four (62%) were on cancer therapy at time of infection and 18 (46%) had received the influenza vaccination that season. Measures of immune status included ANC at time of infection (median 1,530 cells/microl; inter-quartile range, 315, 4347), presence of graft versus host disease 2 (5%) and steroid therapy 4 (10%) patients. All had a low ALC (median 448 cells/microl; IQR 189, 861). Respiratory complications occurred in 8 (20%), ICU admissions in 4 (10%) and death in 2 (5%) patients. Median hospital stay was 2 days. All ICU admissions occurred in unvaccinated patients (P = 0.1). Vaccine status, ANC (<1,000 cells/microl vs. >1,000) and ALC (<500 cells/microl vs. >500) were not associated with length of stay or respiratory complications.

CONCLUSIONS

Influenza infection can be severe in children with cancer and complications occur despite vaccination. Prospective evaluation of vaccine response is worthy of future study.

Influenza virus B-associated hemophagocytic syndrome and recurrent pericarditis in a patient with systemic lupus erythematosus

We report a 24-year-old male with systemic lupus erythematosus (SLE) who developed influenza virus B-associated hemophagocytic syndrome and cardiac tamponade. Although the patient's general condition improved after steroid pulse therapy and pericardiocentesis, pericardial effusion re-accumulated. Colchicine and aspirin were administered, together with prednisolone, after which no further relapses occurred. This was a rare case of severe influenza-associated hemophagocytic syndrome and steroid-resistant pericardial effusion in an SLE patient.

Influenza vaccination in children being treated with chemotherapy for cancer

BACKGROUND

Influenza infection is a potential cause of severe morbidity in children with cancer, therefore vaccination against influenza is recommended. However, there are conflicting data concerning the immune response to influenza vaccination in children with cancer and the value of vaccination remains unclear.

OBJECTIVES

1. To assess the efficacy of influenza vaccination in stimulating immunological response in children with cancer during chemotherapy, compared to control groups. 2. To assess the efficacy of influenza vaccination in preventing confirmed influenza and influenza-like illness and/or stimulating immunological response in children with cancer treated with chemotherapy, compared to placebo, no intervention or different dosage schedules. 3. To determine the adverse effects associated with influenza vaccination in children with cancer.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE (1966 to 2007) and EMBASE (1980 to 2007) up to February 2007. We also searched reference lists of relevant articles and conference proceedings of ICAAC, IDSA, MASCC and SIOP.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in which the serologic response to influenza vaccination of children with cancer was compared to other control groups. We also considered RCTs and CCTs comparing the effects of influenza vaccination on clinical response and/or immunological response in children with cancer, with placebo, no intervention or different dosage schedules.

DATA COLLECTION AND ANALYSIS

Two independent authors assessed the methodological quality of included studies and extracted data.

MAIN RESULTS

We included 1 RCT and 8 CCTs ( total number of participants=708). None of the included studies reported on clinical outcome. All included studies reported on influenza immunity and adverse reactions to vaccination. In five studies, immune responses to influenza vaccine were compared in 272 children on chemotherapy with 166 children not on chemotherapy. In three studies, responses to influenza vaccine were assessed in 204 children on chemotherapy compared with responses in 112 healthy children. The measures used to assess immune responses were: a four-fold rise in antibody titre after vaccination, development of haemagglutination inhibition (HI) titre > 32, and pre- and post-vaccination geometric mean titres (GMT). Immune responses in children receiving chemotherapy were consistently weaker (four-fold rise of 25% to 52%) than in those children who had completed chemotherapy (50% to 86%) and in healthy children (71% to 89%). Concerning adverse effects, 359 paediatric oncology patients received influenza vaccine and the side effects described were mild local reactions and low grade fever. No life-threatening or persistent adverse effects were reported.

AUTHORS' CONCLUSIONS

Paediatric oncology patients receiving chemotherapy are able to generate an immune response to the influenza vaccine, but it remains unclear whether this immune response protects them from influenza infection or its complications. We are awaiting results from well-designed RCTs addressing the clinical benefit of influenza vaccination in these patients.

Infections associated with haemophagocytic syndrome

Haemophagocytic syndrome or haemophagocytic lymphohistiocytosis is a rare disease that is often fatal despite treatment. Haemophagocytic syndrome is caused by a dysregulation in natural killer T-cell function, resulting in activation and proliferation of lymphocytes or histiocytes with uncontrolled haemophagocytosis and cytokine overproduction. The syndrome is characterised by fever, hepatosplenomegaly, cytopenias, liver dysfunction, and hyperferritinaemia. Haemophagocytic syndrome can be either primary, with a genetic aetiology, or secondary, associated with malignancies, autoimmune diseases, or infections. Infections associated with haemophagocytic syndrome are most frequently caused by viruses, particularly Epstein-Barr virus (EBV). We present a case of EBV-associated haemophagocytic syndrome in a young adult with no known immunosuppression. We briefly review haemophagocytic syndrome and then discuss its associated infections, particularly EBV and other herpes viruses, HIV, influenza, parvovirus, and hepatitis viruses, as well as bacterial, fungal, and parasitic organisms.

Hemophagocytic lymphohistiocytosis complicating influenza A infection

During the influenza A (H3N2) season of 2003-2004, several influenza-related complications and deaths were reported in children. Hemophagocytic lymphohistiocytosis complicating influenza A infection is very rare. We report a 3-year-old girl who presented with severe pneumonia and hemophagocytic lymphohistiocytosis associated with influenza A infection. Clinicians should be aware of hemophagocytic syndrome as a serious complication of influenza A infection.

Virus associated hemophagocytic syndrome accompanied by acute respiratory failure caused by influenza A (H3N2)

A 40-year-old Japanese woman was admitted to Oita University Hospital with progressive dyspnea, consciousness disturbance and severe cytopenias. Her chest roentgenogram showed diffuse bilateral infiltrates. She was therefore forced to receive mechanical ventilation. Bone marrow aspiration disclosed numerous hemophagocytic histiocytes, thus suggesting her condition to be hemophagocytic syndrome. In addition, she also developed myocarditis and renal failure. Pulsed methylprednisolone, gamma-globulin, granulocyte colony-stimulating factor and sivelestat sodium hydrate were administrated, and thereafter the patient recovered from cytopenia and organ failure. Afterwards, influenza A H3N2 was detected from bronchial extracts. We should recognize that an influenza A virus infection can induce hemophagocytic syndrome and acute respiratory failure as the initial manifestations of multiple organ failure.

Immune response after influenza vaccination in children with cancer

PURPOSE

To assess the immune response to inactivated trivalent split influenza vaccine in children with cancer.

PROCEDURES

Forty-four children with various types of malignancies received two doses of influenza vaccine 2-4 weeks apart. Hemagglutinin-inhibition (HI) antibody titers were determined in paired sera obtained just before the first vaccination and 4 weeks after the second vaccination.

RESULTS

Influenza vaccine was administered to all children without any serious adverse effects. Protective titer rates (proportion of patients achieving antibody titers > or =40 among those with pre-vaccination titers <40) and response rates (proportion of patients with fourfold or more antibody rise) were 72% and 65% for H1N1, 60% and 40% for H3N2, and 38% and 46% for influenza B, respectively. However, patients on chemotherapy showed a significantly lower immune response to influenza A than those having completed chemotherapy; protection titer rates were 42% versus 90% for H1N1 (P = 0.006) and 25% versus 83% for H3N2 (P = 0.019). For influenza B, patients with low IgG showed a lower response rate than those with high IgG (29% vs. 61%, P = 0.040). Multivariate analysis revealed that factors significantly associated with a lower immune response were low IgG (P < 0.001) and administration of chemotherapy (P = 0.003) for H1N1, administration of chemotherapy (P = 0.008) for H3N2, and low white blood cell (WBC) count (P = 0.030) and low IgG (P = 0.030) for influenza B.

CONCLUSIONS

Influenza vaccination given to children with cancer was safe and induced immune reaction comparable to healthy children, although patients on chemotherapy and/or with chemotherapy-related conditions had a limited ability to produce a sufficient immune response.

Influenza immunisation in children with solid tumours

We assessed response to immunisation with trivalent split virus influenza vaccine in children with non-leukaemic malignant disease. Children with solid tumours and lymphoma received one or two doses of influenza vaccine, according to current UK guidelines, in autumn 2001 and/or 2002. Children were currently receiving chemotherapy or were within 6 months of completing chemotherapy. Pre and post vaccination sera were assessed for antibodies to the prevalent influenza strains by haemagglutination inhibition (HI). Sixty six children were assessed prior to 69 episodes of vaccination. In 30% episodes, children were susceptible to all three circulating influenza viruses (65% to H1N1, 42% to H3N2 and 90% to B) and only one patient showed protective titres (HI32) against all three strains. Seroresponse rates (4-fold rise in HI) for H1N1, H3N2 and B were 52%, 33% and 51% in 65 episodes. Following immunisation protective titres to all three viruses were seen in 25 episodes (38%) and protective responses to one or two viruses were seen in a further 12 (19%) episodes. There was no significant difference in response rates among children on treatment and off treatment and by intensity of chemotherapy. Children with solid tumours and lymphoma are highly susceptible to influenza infection. Influenza vaccine was well tolerated in this patient group and children showed a significant response to immunisation. These findings support the recommendation for annual influenza vaccination in these children.

Immune responses to influenza immunization in children receiving maintenance chemotherapy for acute lymphoblastic leukemia

PURPOSE

To compare the immune responses to influenza vaccine in children with acute lymphoblastic leukemia (ALL) receiving maintenance chemotherapy with those in healthy children.

METHODS

Hemagglutinin-inhibition (HAI) antibody titers were determined before and after influenza vaccination in children with ALL and healthy controls. Immune responses were measured as geometric mean titers (GMT) and 4-fold rises in HAI titers.

RESULTS

Although post-immunization GMT were lower in children with ALL compared to healthy children for the H1N1 antigen (P<0.001), the H3N2 antigen (P=0.03), and for the influenza B antigen (P=0.003), at least 60% of children with ALL had at least a 4-fold rise in HAI titers to each of the influenza antigens.

CONCLUSIONS

While the GMT after trivalent influenza immunization in children with ALL were significantly lower than those seen in healthy children, the majority of children with ALL had 4-fold rises in HAI titers. Children receiving maintenance chemotherapy for ALL should receive yearly influenza vaccine.

Pathology of human influenza A (H5N1) virus infection in cynomolgus macaques (Macaca fascicularis)

Infection with influenza A (H5N1) virus, which has not been associated with respiratory disease in humans previously, caused clinical signs of acute respiratory distress syndrome and multiple-organ dysfunction syndrome with high mortality in humans in Hong Kong in 1997. To study the pathogenesis of this disease, we infected four cynomolgus monkeys (Macaca fascicularis) with 2.5 x 104 median tissue culture infectious dose (TCID50) of influenza virus A/Hong Kong/156/97 (H5N1) and euthanatized them 4 or 7 days after infection. The main lesion was a necrotizing broncho-interstitial pneumonia (4/4) similar to those found in primary influenza virus pneumonia in humans, with desquamation of respiratory epithelium (4/4), intra-alveolar hemorrhage (4/4), hyaline membrane formation (2/4), and infiltration with neutrophils and macrophages (4/4). Lesions in other organs consisted of a suppurative tonsillitis (2/4) and necrosis in lymphoid organs (1/4), kidney (1/4), and liver (1/4). By immunohistochemistry, influenza virus antigen was limited to pulmonary tissue (4/4) and tonsils (2/4). Based on these results, we suggest that the cynomolgus monkey is a suitable animal model for studying the pathogenesis of human H5N1 virus infection and that multiple-organ dysfunction syndrome in this disease may be caused by diffuse alveolar damage from virus replication in the lungs alone.

Response to influenza immunisation during treatment for cancer

AIMS

To assess the annual risk of influenza infection in children with cancer and the immunogenicity of a trivalent split virus influenza vaccine in these children.

METHODS

Eighty four children with cancer were tested for susceptibility to the circulating strains of influenza virus in autumn 1995 and 1996. Non-immunised children were reassessed the following spring for serological evidence of natural infection. Forty two patients received two doses of influenza vaccine. These children were receiving continuing chemotherapy for acute lymphoblastic leukaemia or were within six months of completing chemotherapy.

RESULTS

Among the 84 children tested for influenza virus susceptibility only 8% of patients were fully protected (antibody titres >/= 40) against all three of the prevalent influenza virus strains; 33% were susceptible to all three viruses. Evidence of acquired natural infection was seen in 30% of unimmunised patients. Among immunised susceptible patients, 66% made some protective response to the vaccine and 55% showed protective antibody titres to all three viral strains following vaccination. Older age was associated with increased response to the H1N1 and H3N2 vaccine components, but total white cell count or neutrophil count at immunisation, type of cancer, or length of time on treatment for acute lymphoblastic leukaemia did not affect response.

CONCLUSIONS

Most children with cancer studied were at risk of influenza infection. A significant response to immunisation was seen, supporting annual influenza vaccination for children being treated for cancer.

Pathology of fatal human infection associated with avian influenza A H5N1 virus

Eighteen cases of human influenza A H5N1 infection were identified in Hong Kong from May to December 1997. Two of the six fatal cases had undergone a full post-mortem which showed reactive hemophagocytic syndrome as the most prominent feature. Other findings included organizing diffuse alveolar damage with interstitial fibrosis, extensive hepatic central lobular necrosis, acute renal tubular necrosis and lymphoid depletion. Elevation of soluble interleukin-2 receptor, interleukin-6 and interferon-gamma was demonstrated in both patients, whereas secondary bacterial pneumonia was not observed. Virus detection using isolation, reverse transcription-polymerase chain reaction and immunostaining were all negative. It is postulated that in fatal human infections with this avian subtype, initial virus replication in the respiratory tract triggers hypercytokinemia complicated by the reactive hemophagocytic syndrome. These findings suggest that the pathogenesis of influenza A H5N1 infection might be different from that of the usual human subtypes H1-H3.

An outbreak of influenza A in a neonatal intensive care unit

OBJECTIVES

Investigation of an outbreak of influenza A in a neonatal intensive care unit (NICU) with examination of risk factors for infection and outcomes.

DESIGN

Retrospective cohort study of infants admitted to the unit during the outbreak period. Prospective survey of NICU staff and mothers of infants in the cohort study.

SETTING

Level III nursery in a university-affiliated tertiary referral center.

RESULTS

Nineteen infants in the NICU were infected with influenza A There were six symptomatic cases and one death who had evidence of virus-associated hemophagocytic syndrome at autopsy. Amantadine prophylaxis was offered to the NICU staff, and amantadine therapy was given to five of the six symptomatic infants. Mechanical ventilation, gestational age, birth weight, Clinical Risk Index for Babies score, and twin pregnancy were associated with acquisition of influenza A on univariate analysis. Mechanical ventilation (odds ratio [OR], 6.2; P=.02) and twin pregnancy (OR, 7.0; P=.04) remained as significant risk factors for infection on multiple logistic regression analysis. Only 15% of respondents to the NICU staff survey were vaccinated against influenza. There was no association between a history of an influenza-like illness during pregnancy and acquisition of influenza A by infants of mothers who responded to the maternal survey (OR, 0.91; P=1.0).

CONCLUSIONS

Influenza A is an important pathogen in the neonatal population and is readily transmissible in the NICU setting.

Haemophagocytic syndrome associated with infections

Haemophagocytic syndromes (HS) are the clinical manifestation of an increased macrophagic activity with haemophagocytosis. Pathophysiology is related to a deregulation of T-lymphocytes and excessive production of cytokines. The main clinicobiological features are fever, hepatosplenomegaly, adenopathies, skin rash, neurological features, cytopenias, hypertriglyceridaemia, hyperferritinaemia and coagulopathy. Diagnosis is based on examination of the bone marrow which shows benign histiocytes actively phagocytosing haemopoietic cells. Acquired HS are mostly associated with an underlying disease such as immunodeficiency, haematological neoplasias and autoimmune diseases. Infection-associated HS was originally described by Risdall in 1979, in viral disease. Since the initial description HS has also been documented in patients with bacterial, parasitic or fungal infections. Epstein-Barr virus (EBV) is the causative agent in most cases. In EBV-associated HS, which sometimes has a fatal course, unregulated T-cell reaction or uncontrolled B-cell proliferation may release cytokines. Management of HS consists of early diagnosis, careful screening for, and prompt treatment of, infections and detection and therapy of any underlying disease. Prognosis of infection-associated haemophagocytic syndrome (IAHS) is better than that in other types of secondary HS. Management of cytokine imbalance should be useful to improve the outcome and reduce the mortality rate in these cases.

Virus-associated haemophagocytic syndrome caused by rubella in an adult

Haemophagocytic syndrome is a systemic clinicopathological entity characterized by systemic proliferation of benign haemophagocytic histiocytes, fever, cytopenia, abnormal liver function and, frequently, coagulopathy and hepatosplenomegaly. Its occurrence has been documented in association with viral, bacterial, fungal and parasitic infections, a wide spectrum of malignant neoplasms, autoimmune diseases and drugs. We report a case of rubella virus-associated haemophagocytic syndrome in a previously healthy 29-year-old woman. Blood tests showed cytopenia, especially severe thrombocytopenia, liver dysfunction, hyperferritinaemia and hypercytokinaemia. Bone marrow examination showed many mature histiocytes with active haemophagocytosis. A skin biopsy from the rash revealed perivascular lymphohistiocytic infiltrates with haemophagocytic histiocytes in the upper and mid-dermis. The patient was treated with antibiotics and immunoglobulin, and by supportive measures including platelet transfusion, and recovered completely.

Biomarker and morphological characteristics of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis

BACKGROUND

Viruses may induce primary as well as secondary hemophagocytic lymphohistiocytosis (HLH), but it may not be possible to discriminate between these two in patients with a negative family history. Among these HLH cases, fulminant and fatal virus-associated hemophagocytic syndrome (VAHS) occurs mostly in relation to Epstein-Barr virus (EBV) infection. Although the immunological characteristics of EB-VAHS were previously reported, data on non-EB-VAHS were sporadic and fragmentary. This study has compared the clearly distinguishable groups of EBV-positive vs. EBV-negative HLH cases.

PROCEDURE

Among 26 patients with EBV-related HLH and 12 patients with non-EBV HLH, peripheral blood mononuclear cell (PBMC) subsets and serum concentrations of cytokines at the active phase of the disease were compared. Blood and bone marrow smears were also compared.

RESULTS AND CONCLUSIONS

The frequency of the CD3+HLADR+ subset in PBMC (median 34.3% vs. 4.8%), of serum concentrations of interferon (IFN)-gamma (median 105 U/ml vs. 2.4 U/ml), and of soluble interleukin-2-receptor (sIL-2R) (median 14,700 U/ml vs. 3,412 U/ml) were significantly different between these two groups. Morphological characteristics were noted for EBV-related HLH cases. Mortality also differed between these two groups, 9/26 vs. 0/12 (P = 0.05). Data indicate pronounced immunological imbalance and poor prognosis in EBV-related HLH cases. These parameters could be useful for determining an EBV involvement as well as risk factors in the early care and treatment of HLH patients.

The use of cyclosporin-A in the treatment of virus-associated hemophagocytic syndrome in adults

Virus-associated hemophagocytic syndrome (VAHS) is one of the categories of hemophagocytic syndrome (HPS) which is a clinicopathologic entity characterized by systemic proliferation of benign hemophagocytic cells of the monocyte-macrophage-histiocyte lineage, associated with fever, cytopenia, hepatosplenomegaly, lymphadenopathy, and coagulopathy. The disease affects children and adults after infection with various viruses. However, clinical manifestations are quite different between children and adults. Although the etiology of VAHS is not fully understood, accumulating evidence has revealed dysregulation of the immune system. Standard treatment of VAHS has not been established, yet, but successful trials aiming at immunomodulation have been reported. In this report, current concepts and clinical features of VAHS are reviewed, focusing on the recently introduced cyclosporin A therapy in VAHS in adults.

The presence of Epstein-Barr virus in multiple organs in a fatal case of virus-associated haemophagocytic syndrome

We describe a case report of a 21-year-old male with fatal Epstein-Barr virus-associated haemophagocytic syndrome. Virus is detected in multiple organs by polymerase chain reaction and in the tissue-specific cells of those organs by in situ hybridisation. It is suggested that organ failure may be a direct response to infection.

Virus-associated haemophagocytic syndrome: further evidence for a T-cell mediated disorder

A 16-year-old youth with life-threatening virus-associated haemophagocytic syndrome (VAHS) responded remarkably to treatment with cyclosporin A during two periods of active disease, the second of which was due to noncompliance with treatment. Our clinical observations support the hypothesis that VAHS is cytokine driven as a result of an aberrant T-cell response to infection.

Intravenously administered immune globulin for the treatment of infection-associated hemophagocytic syndrome

Infection-associated hemophagocytic syndrome is an unusual disease with a high mortality rate. A variety of treatment modalities have been used with limited success. We report three patients with infection-associated hemophagocytic syndrome successfully treated with intravenously administered immune globulin.

Hepatitis A causing a second episode of virus-associated haemophagocytic lymphohistiocytosis in a patient with Still's disease

A 20-year-old female with Still's disease who had contracted hepatitis A became critically ill 2 weeks after the onset of jaundice with pancytopenia, coagulopathy, deteriorating liver function tests, and hepatomegaly. The diagnosis of virus-associated haemophagocytic lymphohistiocytosis was made, and she improved slowly after supportive treatment with parenteral steroids and immunoglobulin. Twelve years earlier, at the onset of her arthritis, she had suffered a similar episode of haemophagocytic lymphohistiocytosis in association with Epstein-Barr virus infection.