Human metapneumovirus infection after allogeneic hematopoietic stem cell transplantation

Upper and/or Lower Respiratory Tract Infection Caused by Human Metapneumovirus After Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Human metapneumovirus (hMPV) epidemiology, clinical characteristics and risk factors for poor outcome after allogeneic stem cell transplantation (allo-HCT) remain a poorly investigated area.

METHODS

This retrospective multicenter cohort study examined the epidemiology, clinical characteristics, and risk factors for poor outcomes associated with human metapneumovirus (hMPV) infections in recipients of allo-HCT.

RESULTS

We included 428 allo-HCT recipients who developed 438 hMPV infection episodes between January 2012 and January 2019. Most recipients were adults (93%). hMPV infections were diagnosed at a median of 373 days after allo-HCT. The infections were categorized as upper respiratory tract disease (URTD) or lower respiratory tract disease (LRTD), with 60% and 40% of cases, respectively. Patients with hMPV LRTD experienced the infection earlier in the transplant course and had higher rates of lymphopenia, neutropenia, corticosteroid use, and ribavirin therapy. Multivariate analysis identified lymphopenia and corticosteroid use (>30 mg/d) as independent risk factors for LRTD occurrence. The overall mortality at day 30 after hMPV detection was 2% for URTD, 12% for possible LRTD, and 21% for proven LRTD. Lymphopenia was the only independent risk factor associated with day 30 mortality in LRTD cases.

CONCLUSIONS

These findings highlight the significance of lymphopenia and corticosteroid use in the development and severity of hMPV infections after allo-HCT, with lymphopenia being a predictor of higher mortality in LRTD cases.

Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances

Before the COVID-19 pandemic, common community-acquired seasonal respiratory viruses (CARVs) were a significant threat to the health and well-being of allogeneic hematopoietic cell transplant (allo-HCT) recipients, often resulting in severe illness and even death. The pandemic has further highlighted the significant risk that immunosuppressed patients, including allo-HCT recipients, face when infected with SARS-CoV-2. As preventive transmission measures are relaxed and CARVs circulate again among the community, including in allo-HSCT recipients, it is crucial to understand the current state of knowledge, gaps, and recent advances regarding CARV infection in allo-HCT recipients. Urgent research is needed to identify seasonal respiratory viruses as potential drivers for future pandemics.

Human metapneumovirus infection in haematopoietic stem cell transplant recipients: a case series

Human metapneumovirus (hMPV) is an enveloped virus that causes serious respiratory tract infection among immunocompromised populations especially haematopoietic stem cell transplant (HSCT) recipients. Here, we describe 3 cases of hMPV infection which led to mortality among post HSCT adults. 66 post HSCT adults enrolled between January 2017 and March 2019 at Dr. B. R. Ambedkar Institute Rotary Cancer Hospital, AIIMS, New Delhi, were followed up for a period varying from 16 days to 18 months for any episode of respiratory illness until March 2019. Real time reverse transcriptase polymerase chain reaction (rRT-PCR) was used to detect the virus from appropriate specimens when symptoms of acute respiratory infection appeared. Samples from 88 out of a total of 172 episodes of suspected acute respiratory infection could be tested by rRT-PCR. Of these, 9 episodes were positive for hMPV. Three patients with hMPV associated lower respiratory tract infection (LRTI) expired within 30 days of HSCT. The possible risk factors associated with mortality included LRTI, infection during early post-transplant period (first week following HSCT), absolute lymphocyte count less than 200/µl, absolute neutrophil count less than 500/µl, use of steroid within 30 days prior to infection and need for mechanical ventilation.

Viruses and atypical bacteria in the respiratory tract of immunocompromised and immunocompetent patients with airway infection

Respiratory tract infections (RTI) can take a serious course under immunosuppression. Data on the impact of the underlying pathogens are still controversial. Samples from the upper (n = 322) and lower RT (n = 169) were collected from 136 children and 355 adults; 225 among them have been immunocompromised patients. Exclusion criteria were presence of relevant cultivable microorganisms, C-reactive protein > 20 mg/dl, or procalcitonin > 2.0 ng/ml. Samples were tested by PCR for the presence of herpesviruses (HSV-1/-2; VZV; CMV; HHV6; EBV), adenoviruses, bocaviruses, entero-/rhinoviruses (HRV), parechoviruses, coronaviruses, influenza viruses (IV), parainfluenza viruses as well as for pneumoviruses (HMPV and RSV), and atypical bacteria (Mycoplasma pneumoniae, M.p.; Chlamydia pneumoniae, C.p.). Viral/bacterial genome equivalents were detected in more than two-thirds of specimens. Under immunosuppression, herpesviruses (EBV 30.9%/14.6%, p < 0.001; CMV 19.6%/7.9%, p < 0.001; HSV-1: 14.2%/7.1%, p = 0.012) were frequently observed, mainly through their reactivation in adults. Immunocompromised adults tended to present a higher RSV prevalence (6.4%/2.4%, p = 0.078). Immunocompetent patients were more frequently tested positive for IV (15.0%/5.8%, p = 0.001) and M.p. (6.4%/0.4%, p < 0.001), probably biased due to the influenza pandemic of 2009 and an M.p. epidemic in 2011. About 41.8% of samples were positive for a single pathogen, and among them EBV (19.9%) was most prevalent followed by HRV (18.2%) and IV (16.6%). HSV-2 and C.p. were not found. Marked seasonal effects were observed for HRV, IV, and RSV. Differences in pathogen prevalence were demonstrated between immunocompetent and immunocompromised patients. The exact contribution of some herpesviruses to the development of RTI remains unclear.

ACR Appropriateness Criteria® Acute Respiratory Illness in Immunocompromised Patients

The immunocompromised patient with an acute respiratory illness (ARI) may present with fever, chills, weight loss, cough, shortness of breath, or chest pain. The number of immunocompromised patients continues to rise with medical advances including solid organ and stem cell transplantation, chemotherapy, and immunomodulatory therapy, along with the continued presence of human immunodeficiency virus and acquired immunodeficiency syndrome. Given the myriad of pathogens that can infect immunocompromised individuals, identifying the specific organism or organisms causing the lung disease can be elusive. Moreover, immunocompromised patients often receive prophylactic or empiric antimicrobial therapy, further complicating diagnostic evaluation. Noninfectious causes for ARI should also be considered, including pulmonary edema, drug-induced lung disease, atelectasis, malignancy, radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, and pulmonary thromboembolic disease. As many immunocompromised patients with ARI progress along a rapid and potentially fatal course, timely selection of appropriate imaging is of great importance in this setting. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking, or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Community-Acquired Respiratory Viruses in Transplant Patients: Diversity, Impact, Unmet Clinical Needs

Patients undergoing solid-organ transplantation (SOT) or allogeneic hematopoietic cell transplantation (HCT) are at increased risk for infectious complications. Community-acquired respiratory viruses (CARVs) pose a particular challenge due to the frequent exposure pre-, peri-, and posttransplantation. Although influenza A and B viruses have a top priority regarding prevention and treatment, recent molecular diagnostic tests detecting an array of other CARVs in real time have dramatically expanded our knowledge about the epidemiology, diversity, and impact of CARV infections in the general population and in allogeneic HCT and SOT patients. These data have demonstrated that non-influenza CARVs independently contribute to morbidity and mortality of transplant patients. However, effective vaccination and antiviral treatment is only emerging for non-influenza CARVs, placing emphasis on infection control and supportive measures. Here, we review the current knowledge about CARVs in SOT and allogeneic HCT patients to better define the magnitude of this unmet clinical need and to discuss some of the lessons learned from human influenza virus, respiratory syncytial virus, parainfluenzavirus, rhinovirus, coronavirus, adenovirus, and bocavirus regarding diagnosis, prevention, and treatment.

Superinfection and cell regeneration can lead to chronic viral coinfections

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Clinical researchers have found that coinfection of the respiratory tract can cause distinct disease outcome, sometimes leading to long-lasting infection, compared to single viral infection.

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The impact of coinfections in human respiratory tract have not yet been evaluated in either theoretical or experimental studies on a large scale.

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A few experiments confirm that different respiratory viruses can infect the same cell (superinfection).

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Superinfection alone cannot cause long-lasting viral coinfections.

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The combined mechanism of superinfection and cell regeneration provides a plausible mechanism for chronic viral coinfections.

Molecular diagnostic techniques have revealed that approximately 43% of the patients hospitalized with influenza-like illness are infected by more than one viral pathogen, sometimes leading to long-lasting infections. It is not clear how the heterologous viruses interact within the respiratory tract of the infected host to lengthen the duration of what are usually short, self-limiting infections. We develop a mathematical model which allows for single cells to be infected simultaneously with two different respiratory viruses (superinfection) to investigate the possibility of chronic coinfections. We find that a model with superinfection and cell regeneration has a stable chronic coinfection fixed point, while superinfection without cell regeneration produces only acute infections. This analysis suggests that both superinfection and cell regeneration are required to sustain chronic coinfection via this mechanism since coinfection is maintained by superinfected cells that allow slow-growing infections a chance to infect cells and continue replicating. This model provides a possible mechanism for chronic coinfection independent of any viral interactions via the immune response.

Febrile Neutropenia in Transplant Recipients

Febrile neutropenic patients are at increased risk of developing infections. During the initial stages of neutropenia, most of these infections are bacterial. The spectrum of bacterial infections depends to some extent on whether or not patients receive antimicrobial prophylaxis when neutropenic. Since most transplant recipients do, Gram-positive organisms predominate, due to the fact prophylaxis is directed primarily against Gram-negative organisms. Staphylococcus species (often methicillin-resistant), Streptococcus species (viridans group streptococci, beta-hemolytic streptococci), and Enterococcus species (including vancomycin-resistant strains) are isolated most often. Therefore, potent empiric Gram-positive coverage is recommended by many in this setting. Escherichia coli, Pseudomonas aeruginosa, and Klebsiella species are the most common Gram-negative pathogens isolated. Non-fermentative Gram-negative bacilli (Stenotrophomonas maltophilia, Acinetobacter species) are emerging as important pathogens. Many of these organisms acquire multiple mechanisms of resistance that render them multidrug resistant. The administration of prompt, broad-spectrum, empiric, antimicrobial therapy is essential and is generally based on local epidemiology and susceptibility/resistance patterns. Response rate to the initial regimen is generally in the range of 75–85%. Fungal infections develop in patients with prolonged neutropenia (greater than 7–10 days). Candida species and Aspergillus species are the predominant fungal pathogens, although many other fungi are opportunistic pathogens in this setting. Fungal infections are seldom documented microbiologically or on histopathology, and the administration of empiric antifungal therapy, when such infections are suspected, is the norm. Therapy is often prolonged, and outcomes are still suboptimal. The importance of infection control and antimicrobial stewardship cannot be overemphasized.

Prophylactic and therapeutic approaches for human metapneumovirus

Human metapneumovirus (HMPV) is an important pneumovirus which causes acute respiratory disease in human beings. The viral infection leads to mild to severe respiratory symptoms depending on the age and immune status of the infected individual. Several groups across the world are working on the development of immunogens and therapy to manage HMPV infection with promising results under laboratory conditions but till date any virus specific vaccine or therapy has not been approved for clinical use. This minireview gives an overview of the prophylactic and therapeutic approaches to manage HMPV infections.

Viral pneumonia: etiologies and treatment

Viral pathogens are increasingly recognized as a cause of pneumonia, in immunocompetent patients and more commonly among immunocompromised. Viral pneumonia in adults could present as community-acquired pneumonia (CAP), ranging from mild disease to severe disease requiring hospital admission and mechanical ventilation. Moreover, the role of viruses in hospital-acquired pneumonia and ventilator-associated pneumonia as causative agents or as co-pathogens and the effect of virus detection on clinical outcome are being investigated.More than 20 viruses have been linked to CAP. Clinical presentation, laboratory findings, biomarkers, and radiographic patterns are not characteristic to specific viral etiology. Currently, laboratory confirmation is most commonly done by detection of viral nucleic acid by reverse transcription-PCR of respiratory secretions.Apart from the US Food and Drug Administration-approved medications for treatment of influenza pneumonia, the treatment of non-influenza respiratory viruses is limited. Moreover, the evidence supporting the use of available antivirals to treat immunocompromised patients is modest at best. With the widespread use of molecular diagnostics, an aging population, and advancement in cancer therapy, physicians will face a bigger challenge in managing viral respiratory tract infections. Emphasis on infection control measures to prevent the spread of respiratory viruses especially in healthcare settings is extremely important.

Community-Acquired Respiratory Paramyxovirus Infection After Allogeneic Hematopoietic Cell Transplantation: A Single-Center Experience

Background

Paramyxoviruses include respiratory syncytial virus (RSV), parainfluenza virus (PIV), and human metapneumovirus (MPV), which may cause significant respiratory tract infectious disease (RTID) and mortality after allogeneic hematopoietic cell transplantation (HCT). However, clinical data regarding frequency and outcome are scarce.

Methods

We identified all paramyxovirus RTIDs in allogeneic HCT recipients diagnosed by multiplex polymerase chain reaction between 2010 and 2014. Baseline characteristics of patients, treatment, and outcome of each episode were analyzed; ie, moderate, severe, and very severe immunodeficiency (verySID) according to HCT ≤6 months, T- or B-cell depletion ≤3 months, graft-versus-host disease, neutropenia, lymphopenia, or hypo-gammaglobulinemia.

Results

One hundred three RTID episodes in 66 patients were identified (PIV 47% [48 of 103], RSV 32% [33 of 103], MPV 21% [22 of 103]). Episodes occurred in 85% (87 of 103) at >100 days post-HCT. Lower RTID accounted for 36% (37 of 103). Thirty-nine percent (40 of 103) of RTID episodes required hospitalization and more frequently affected patients with lower RTID. Six percent progressed from upper to lower RTID. Overall mortality was 6% and did not differ between paramyxoviruses. Sixty-one percent (63 of 103) of episodes occurred in patients with SID, and 20.2% (19 of 63) of episodes occurred in patients with verySID. Oral ribavirin plus intravenous immunoglobulin was administered in 38% (39 of 103) of RTIDs, preferably for RSV or MPV (P ≤ .001) and for SID patients (P = .001). Patients with verySID frequently progressed to lower RTID (P = .075), required intensive care unit transfer, and showed higher mortality.

Conclusion

Paramyxovirus RTID remains a major concern in allogeneic HCT patients fulfilling SID and verySID, emphasizing that efficacious and safe antiviral treatments are urgently needed.

Intraoperative Acute Respiratory Failure in an Immunocompromised Patient with Human Metapneumovirus

Patient: Male, 31

Final Diagnosis: Pneumonia from Human Metapneumovirus pulmonary infection

Symptoms: Cough • fatigue

Medication: —

Clinical Procedure: Hernia repair

Specialty: Anesthesiology

Human Parainfluenza Virus Type 3 Infections in Patients with Hematopoietic Stem Cell Transplants: the Mode of Nosocomial Infections and Prognosis

There have been a few prospective and comprehensive surveillance studies on the respiratory viral infections (RVIs) among patients undergoing hematopoietic stem cell transplantation (HSCT). A 2-year prospective cohort surveillance study of symptomatic and asymptomatic RVIs was performed in hospitalized HSCT patients. Oropharyngeal (OP) swab samples were serially collected each week from 1 week before and up to 100 days after HSCT and were tested for virus isolation with cell culture-based viral isolation (CC-based VI) and a multiplex PCR (MPCR). A total of 2,747 OP swab samples were collected from 250 HSCT patients (268 HSCT procedures). Among these patients, 79 had RVIs (CC-based VI, n = 63; MPCR, n = 17). The parainfluenza virus type 3 (PIV3) accounted for 71% (57/80) of the cases of RVIs. Some PIV3 infections were asymptomatic and involved a longer virus-shedding period. The PIV3 was often cultured from samples taken before the onset of a respiratory disease. The PIV3 infections were attributed to the transmission of nosocomial infections. PIV3 infections before engraftment will more likely result in the development of lower respiratory tract infections and worse outcomes. A real-time monitoring of respiratory viral infections in the HSCT ward among patients with or without respiratory symptoms is required for the prevention of nosocomial RVIs, especially of PIV3 infections.

Immunologic Profiling of Human Metapneumovirus for the Development of Targeted Immunotherapy

Human metapneumovirus (hMPV) is a respiratory virus detected in ≥9% of allogeneic hematopoietic stem cell transplant (HSCT) recipients, in whom it can cause significant morbidity and mortality. Given the lack of effective antivirals, we investigated the potential for immunotherapeutic intervention, using adoptively transferred T cells. Thus, we characterized the cellular immune response to the virus and identified F, N, M2-1, M, and P as immunodominant target antigens. Reactive T cells were polyclonal (ie, they expressed CD4 and CD8), T-helper type 1 polarized, and polyfunctional (ie, they produced interferon γ, tumor necrosis factor α, granulocyte-macrophage colony-stimulating factor, and granzyme B), and they were able to kill autologous antigen-loaded targets. The detection of hMPV-specific T cells in HSCT recipients who endogenously controlled active infections support the clinical importance of T-cell immunity in mediating protective antiviral effects. Our results demonstrate the feasibility of developing an immunotherapy for immunocompromised patients with uncontrolled infections.

Update in the treatment of non-influenza respiratory virus infection in solid organ transplant recipients

INTRODUCTION

Despite the improved outcomes in solid organ transplantation with regard to prevention of rejection and increased patient and graft survival, infection remains a common cause of morbidity and mortality. Respiratory viruses are a frequent and potentially serious cause of infection after solid organ transplantation. Furthermore, clinical manifestations of respiratory virus infection (RVI) may be more severe and unusual in solid organ transplant recipients (SOTRs) compared with the non-immunocompromised population. Areas covered: This article reviews the non-influenza RVIs that are commonly encountered in SOTRs. Epidemiologic and clinical characteristics are highlighted and available treatment options are discussed. Expert opinion: New diagnostic tools, particularly rapid molecular assays, have expanded the ability to identify specific RVI pathogens in SOTRs. This is not only useful from a treatment standpoint but also to guide infection control practices. More data are needed on RVIs in the solid organ transplant population, particularly regarding their effect on rejection and graft dysfunction. There is also a need for new antiviral agents active against these infections as well as markers that can identify which patients would most benefit from treatment.

Burden of human metapneumovirus infections in patients with cancer: Risk factors and outcomes

BACKGROUND

Human metapneumovirus (hMPV) causes upper and lower respiratory tract infections (URIs and LRIs, respectively) in healthy and immunocompromised patients; however, its clinical burden in patients with cancer remains unknown.

METHODS

In a retrospective study of all laboratory‐confirmed hMPV infections treated at the authors’ institution between April 2012 and May 2015, clinical characteristics, risk factors for progression to an LRI, treatment, and outcomes in patients with cancer were determined.

RESULTS

In total, 181 hMPV infections were identified in 90 patients (50%) with hematologic malignancies (HMs), in 57 (31%) hematopoietic cell transplantation (HCT) recipients, and in 34 patients (19%) with solid tumors. Most patients (92%) had a community‐acquired infection and presented with URIs (67%), and 43% developed LRIs (59 presented with LRIs and 19 progressed from a URI to an LRI). On multivariable analysis, an underlying HM (adjusted odds ratio [aOR], 3.11; 95% confidence interval [CI], 1.12‐8.64; P = .029), nosocomial infection (aOR, 26.9; 95% CI, 2.79‐259.75; P = .004), and hypoxia (oxygen saturation [SpO2], ≤ 92%) at presentation (aOR, 9.61; 95% CI, 1.98‐46.57; P = .005) were identified as independent factors associated with LRI. All‐cause mortality at 30 days from hMPV diagnosis was low (4%), and patients with LRIs had a 10% mortality rate at day 30 from diagnosis; whereas patients with URIs had a 0% mortality rate.

CONCLUSIONS

hMPV infections in patients with cancer may cause significant morbidity, especially for those with underlying HM who may develop an LRI. Despite high morbidity and the lack of directed antiviral therapy for hMPV infections, mortality at day 30 from this infection remained low in this studied population. Cancer 2017;123:2329–2337. © 2017 American Cancer Society.

Human metapneumovirus infections in patients with cancer may cause significant morbidity, especially in those with underlying hematologic malignancies who may develop a lower respiratory infection. Despite high morbidity and the lack of directed antiviral therapy for human metapneumovirus infections, mortality from this infection at day 30 and day 90 remains low in the studied population.

Viral Pneumonia in Patients with Hematologic Malignancy or Hematopoietic Stem Cell Transplantation

Viral pneumonias in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation cause significant morbidity and mortality. Advances in diagnostic techniques have enabled rapid identification of respiratory viral pathogens from upper and lower respiratory tract samples. Lymphopenia, myeloablative and T-cell depleting chemotherapy, graft-versus-host disease, and other factors increase the risk of developing life-threatening viral pneumonia. Chest imaging is often nonspecific but may aid in diagnoses. Bronchoscopy with bronchoalveolar lavage is recommended in those at high risk for viral pneumonia who have new infiltrates on chest imaging.

Community acquired respiratory virus infections in cancer patients-Guideline on diagnosis and management by the Infectious Diseases Working Party of the German Society for haematology and Medical Oncology

BACKGROUND

Community acquired viruses (CRVs) may cause severe disease in cancer patients. Thus, efforts should be made to diagnose CRV rapidly and manage CRV infections accordingly.

METHODS

A panel of 18 clinicians from the Infectious Diseases Working Party of the German Society for Haematology and Medical Oncology have convened to assess the available literature and provide recommendations on the management of CRV infections including influenza, respiratory syncytial virus, parainfluenza virus, human metapneumovirus and adenovirus.

RESULTS

CRV infections in cancer patients may lead to pneumonia in approximately 30% of the cases, with an associated mortality of around 25%. For diagnosis of a CRV infection, combined nasal/throat swabs or washes/aspirates give the best results and nucleic acid amplification based-techniques (NAT) should be used to detect the pathogen. Hand hygiene, contact isolation and face masks have been shown to be of benefit as general infection management. Causal treatment can be given for influenza, using a neuraminidase inhibitor, and respiratory syncytial virus, using ribavirin in addition to intravenous immunoglobulins. Ribavirin has also been used to treat parainfluenza virus and human metapneumovirus, but data are inconclusive in this setting. Cidofovir is used to treat adenovirus pneumonitis.

CONCLUSIONS

CRV infections may pose a vital threat to patients with underlying malignancy. This guideline provides information on diagnosis and treatment to improve the outcome.

Metapneumovirus Infections and Respiratory Complications

Acute respiratory tract infections (ARTIs) are the most common illnesses experienced by people of all ages worldwide. In 2001, a new respiratory pathogen called human metapneumovirus (hMPV) was identified in respiratory secretions. hMPV is an RNA virus of the Paramyxoviridae family, and it has been isolated on every continent and from individuals of all ages. hMPV causes 7 to 19% of all cases of ARTIs in both hospitalized and outpatient children, and the rate of detection in adults is approximately 3%. Symptoms of hMPV infection range from a mild cold to a severe disease requiring a ventilator and cardiovascular support. The main risk factors for severe disease upon hMPV infection are the presence of a high viral load, coinfection with other agents (especially human respiratory syncytial virus), being between 0 and 5 months old or older than 65 years, and immunodeficiency. Currently, available treatments for hMPV infections are only supportive, and antiviral drugs are employed in cases of severe disease as a last resort. Ribavirin and immunoglobulins have been used in some patients, but the real efficacy of these treatments is unclear. At present, the direction of research on therapy for hMPV infection is toward the development of new approaches, and a variety of vaccination strategies are being explored and tested in animal models. However, further studies are required to define the best treatment and prevention strategies.

Human metapneumovirus (hMPV) infection in immunocompromised children

BACKGROUND

Human metapneumovirus (hMPV) is a major cause of upper and lower respiratory tract infection (URTI, LRTI) in children. The prognosis of hMPV is unclear in immunocompromised patients.

OBJECTIVES

To describe the characteristics of hMPV infection in immunocompromised pediatric patients and to review the literature.

STUDY DESIGN

This retrospective study included 39 immunocompromised children (age 0-18 years) with proven hMPV infection attending two tertiary pediatric medical centers in 2004-2014. Demographic, clinical, laboratory, and radiological data were collected from the medical files.

RESULTS

Median age was 6 years. Seven patients had primary immune deficiency and 32, secondary immune deficiency, including 9 patients who underwent hematopoietic stem cell transplantation (HSCT). Most cases (92%) occurred in January-May. Twenty patients (51%) had lower respiratory tract infection and 17 (44%), upper respiratory tract infection; 2 patients (5%) had fever only. Presenting symptoms were fever (70%), cough (54%), and rhinorrhea (35%). Severe lymphopenia (<1000lymphocytes/mL) was noted in 64% of patients and elevated liver enzyme levels in 49%. Seventeen patients had pneumonia: bilateral and alveolar in 13 patients, each. HSCT was not associated with more severe disease. Respiratory failure occurred in 6 patients, of whom 4 died (10% of cohort). All children who died had severe lymphopenia. On multivariate analysis, bacterial or fungal co-infection was the only major risk factor for death. Review of the literature showed variable clinical presentations and severity in pediatric patients with hMPV infection.

CONCLUSIONS

Infection with hMPV may be associated with relatively high morbidity and mortality in immunocompromised children. Death was associated with bacterial and fungal co-infection.

Human metapneumovirus infections in hematopoietic cell transplant recipients and hematologic malignancy patients: A systematic review

Over the past decade, reported incidence of human metapneumovirus (hMPV) has increased owing to the use of molecular assays for diagnosis of respiratory viral infections in cancer patients. The seasonality of these infections, differences in sampling strategies across institutions, and small sample size of published studies make it difficult to appreciate the true incidence and impact of hMPV infections. In this systematic review, we summarized the published data on hMPV infections in hematopoietic cell transplant recipients and patients with hematologic malignancy, focusing on incidence, hMPV-associated lower respiratory tract infection (LRTI), mortality, prevention, and management with ribavirin and/or intravenous immunoglobulins. Although the incidence of hMPV infections and hMPV-associated LRTI in this patient population is similar to respiratory syncytial virus or parainfluenza virus and despite lack of directed antiviral therapy, the mortality rate remains low unless patients develop LRTI. In the absence of vaccine to prevent hMPV, infection control measures are recommended to reduce its burden in cancer patients.

Human Metapneumovirus Infections Following Hematopoietic Cell Transplantation: Factors Associated With Disease Progression

BACKGROUND

Human metapneumovirus (HMPV) is a newly identified pulmonary pathogen that can cause fatal lower respiratory tract disease (LRD) in hematopoietic cell transplantation (HCT) recipients. Little is known about progression rates from upper respiratory tract infection (URI) to LRD and risk factors associated with progression.

METHODS

A total of 118 HCT recipients receiving transplantation between 2004 and 2014 who had HMPV detected in nasopharyngeal, bronchoalveolar lavage, or lung biopsy samples by real-time reverse transcription polymerase chain reaction were retrospectively analyzed.

RESULTS

More than 90% of the cases were identified between December and May. Among the 118 HCT patients, 88 and 30 had URI alone and LRD, respectively. Among 30 patients with LRD, 17 patients progressed from URI to LRD after a median of 7 days (range, 2-63 days). The probability of progression to LRD within 40 days after URI was 16%. In Cox regression analysis, steroid use ≥1 mg/kg prior to URI diagnosis (hazard ratio [HR], 5.10; P = .004), low lymphocyte count (HR, 3.43; P = .011), and early onset of HMPV infection after HCT (before day 30 after HCT; HR, 3.54; P = .013) were associated with higher progression to LRD. The median viral load in nasal wash samples was 1.1 × 10(6) copies/mL (range, 3.3 × 10(2)-1.7 × 10(9)) with no correlation between the viral load and progression.

CONCLUSIONS

Progression from URI to LRD occurred in up to 60% of HCT recipients with risk factors such as systemic corticosteroid use or low lymphocyte counts. Further studies are needed to define the role of viral load in the pathogenesis of progressive disease.

BCSH/BSBMT/UK clinical virology network guideline: diagnosis and management of common respiratory viral infections in patients undergoing treatment for haematological malignancies or stem cell transplantation

A joint working group established by the Haemato-oncology subgroup of the British Committee for Standards in Haematology, the British Society for Bone Marrow Transplantation and the UK Clinical Virology Network has reviewed the available literature and made recommendations for the diagnosis and management of respiratory viral infections in patients with haematological malignancies or those undergoing haematopoietic stem cell transplantation. This guideline includes recommendations for the diagnosis, prevention and treatment of respiratory viral infections in adults and children. The suggestions and recommendations are primarily intended for physicians practising in the United Kingdom.

Oral Ribavirin for the Treatment of Noninfluenza Respiratory Viral Infections: A Systematic Review

OBJECTIVE

To review clinical outcomes data for patients treated with oral ribavirin for noninfluenza respiratory viral infections (NIRVIs).

DATA SOURCES

MEDLINE, EMBASE, and PubMed Central (1972 to June 1, 2015) were queried with the following search term combinations: "Oral" AND "ribavirin" AND ("respiratory syncytial virus" OR "metapneumovirus" OR "parainfluenza" OR "coronavirus" OR "rhinovirus" OR "enterovirus" OR "adenovirus").

STUDY SELECTION AND DATA EXTRACTION

Included studies must have characterized the clinical outcomes of a cohort of patients treated with oral ribavirin for symptomatic NIRVIs. Case reports and series with <5 cases, conference abstracts, and articles written in languages other than English were excluded.

DATA SYNTHESIS

Of the 1256 unique reports, 15 met inclusion criteria: 12 retrospective, 3 prospective, and 3 comparative with untreated control groups. All studies except for 2 Middle East respiratory syndrome coronavirus (MERS-CoV) studies were in immunocompromised patients (9 malignancy/stem cell transplant, 4 lung transplant). The mortality rate ranged from 0% to 31% in malignancy/stem cell transplant recipients treated with oral ribavirin, and 1/108 (0.9%) ribavirin-treated lung transplant recipients died at 30 days. Three studies (one each for malignancy, lung transplant, and MERS-CoV) suggested a clinical outcomes benefit with oral ribavirin compared with supportive care alone; however, the nonrandomized design precludes efficacy determination. Hemolysis was the most common adverse reaction, occurring in 14% (54/375) of patients. Ribavirin was discontinued in 4% of patients secondary to adverse reactions.

CONCLUSIONS

Oral ribavirin should be considered for the treatment of NIRVI in immunocompromised adults (malignancy/stem cell transplant or lung transplant) or adults with MERS-CoV.

Human metapneumovirus pneumonia in patients with hematological malignancies

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25% of hematological patients with a positive HMPV test have pneumonia.

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HMPV pneumonia can occur in the course of several hematological conditions.

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HMPV can cause pneumonia as a single pathogen.

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Lung HRCT scan may be suggestive of HMPV pneumonia.

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The outcome of HMPV pneumonia is good despite no antiviral treatment.

Background

Human metapneumovirus (HMPV) has recently emerged as a cause of respiratory infections in hematological patients. Clinical data are lacking to guide the management of HMPV pneumonias.

Objectives

To characterize the clinical and radiographic presentation and outcome of HMPV pneumonias diagnosed in hematological patients.

Study design

We screened the patients with a positive HMPV respiratory test in two French teaching hospitals between 2007 and 2011. Among them, the medical charts from the hematological patients who presented with HMPV pneumonia were reviewed.

Results

Among the 54 patients with several underlying hematological conditions who were positive for HMPV, we found 13 cases of HMPV pneumonias. HMPV could be the cause of pneumonia as a single pathogen without associated upper respiratory infection. Centrilobular nodules were constant on lung computed tomography scans. No patients died despite the absence of administration of antiviral treatments.

Conclusions

Our data provide further insights in the diagnosis and management of HMPV pneumonias in this setting.

Life-threatening infection in transplant recipients

Modern post-transplant care pathways commonly encompass periods of critical care support. Infectious events account for many of these interactions making critical care physicians integral members of multidisciplinary transplant teams. Despite continuing advances in clinical care and infection prophylaxis, the morbidity and mortality attributable to infection post-transplant remains considerable. Emerging entities constantly add to the breadth of potential opportunistic pathogens. Individualized risk assessments, rapid and thorough diagnostic evaluation, and prompt initiation of appropriate antimicrobial therapies are essential. The approach to managing transplant recipients with infection in critical care is discussed and common and emerging opportunistic pathogens are reviewed.

Human metapneumovirus in adults

Human metapneumovirus (HMPV) is a relative newly described virus. It was first isolated in 2001 and currently appears to be one of the most significant and common human viral infections. Retrospective serologic studies demonstrated the presence of HMPV antibodies in humans more than 50 years earlier. Although the virus was primarily known as causative agent of respiratory tract infections in children, HMPV is an important cause of respiratory infections in adults as well. Almost all children are infected by HMPV below the age of five; the repeated infections throughout life indicate transient immunity. HMPV infections usually are mild and self-limiting, but in the frail elderly and the immunocompromised patients, the clinical course can be complicated. Since culturing the virus is relatively difficult, diagnosis is mostly based on a nucleic acid amplification test, such as reverse transcriptase polymerase chain reaction. To date, no vaccine is available and treatment is supportive. However, ongoing research shows encouraging results. The aim of this paper is to review the current literature concerning HMPV infections in adults, and discuss recent development in treatment and vaccination.