Absence of Nosocomial Transmission of Imported Lassa Fever during Use of Standard Barrier Nursing Methods.

Nosocomial transmission of Lassa virus (LASV) is reported to be low when care for the index patient includes proper barrier nursing methods. We investigated whether asymptomatic LASV infection occurred in healthcare workers who used standard barrier nursing methods during the first 15 days of caring for a patient with Lassa fever in Sweden. Of 76 persons who were defined as having been potentially exposed to LASV, 53 provided blood samples for detection of LASV IgG. These persons also responded to a detailed questionnaire to evaluate exposure to different body fluids from the index patient. LASV-specific IgG was not detected in any of the 53 persons. Five of 53 persons had not been using proper barrier nursing methods. Our results strengthen the argument for a low risk of secondary transmission of LASV in humans when standard barrier nursing methods are used and the patient has only mild symptoms.

Investigation of a food-borne outbreak of gastroenteritis in a school canteen revealed a variant of sapovirus genogroup V not detected by standard PCR, Sollentuna, Sweden, 2016.

A food-borne outbreak of gastroenteritis with more than 650 suspected cases occurred in April 2016 in Sollentuna, Sweden. It originated in a school kitchen serving a total of 2,700 meals daily. Initial microbiological testing (for Campylobacter, Salmonella, Shigella, Yersinia, Giardia, Cryptosporidium, Entamoeba histolytica, adeno-, astro-, noro-, rota- and sapovirus) of stool samples from 15 symptomatic cases was negative, despite a clinical presentation suggestive of calicivirus. Analyses of the findings from both the Sollentuna municipality environmental team and a web-based questionnaire suggested that the source of the outbreak was the salad buffet served on 20 April, although no specific food item could be identified. Subsequent electron microscopic examination of stool samples followed by whole genome sequencing revealed a variant of sapovirus genogroup V. The virus was not detected using standard PCR screening. This paper describes the epidemiological outbreak investigation and findings leading to the discovery.

Respiratory viruses associated with community-acquired pneumonia in children: matched case-control study.

BACKGROUND: Community-acquired pneumonia (CAP) is the leading cause of death in children worldwide and a substantial proportion of childhood CAP is caused by viruses. A better understanding of the role of virus infections in this condition is needed to improve clinical management and preventive measures. The aim of the study was therefore to assess the association between specific respiratory viruses and childhood CAP. METHODS: A case-control study was conducted during 3 years in Stockholm, Sweden. Cases were children aged ≤5 years with radiological CAP. Healthy controls were consecutively enrolled at child health units during routine visits and matched to cases on age and calendar time. Nasopharyngeal aspirates were obtained and analysed by real-time PCR for 15 viruses. Multivariate conditional logistic regression was used to account for coinfections with other viruses and baseline characteristics. RESULTS: A total of 121 cases, of which 93 cases met the WHO criteria for radiological pneumonia, and 240 controls were included in the study. Viruses were detected in 81% of the cases (n=98) and 56% of the controls (n=134). Influenza virus, metapneumovirus and respiratory syncytial virus were detected in 60% of cases and were significantly associated with CAP with ORs >10. There was no association with parainfluenza virus, human enterovirus or rhinovirus and coronavirus and bocavirus were negatively associated with CAP. CONCLUSIONS: Our study indicates viral CAP is an underestimated disease and points out hMPV as a new important target for the prevention of childhood CAP.

Bacteremia in Swedish hematological patients with febrile neutropenia: bacterial spectrum and antimicrobial resistance patterns.

BACKGROUND: The etiology of bacteremia in hematological patients with febrile neutropenia differs geographically and changes over time. Since efficient empirical antibiotic treatment depends on relevant knowledge of the bacterial panorama, the aim of this study was to describe the prevalence of bacteremia, the bacterial spectrum, and the resistance patterns of the isolates in this group today. METHODS: In a cross-sectional study, routine blood cultures from febrile episodes occurring in adult patients with hematological disorders and neutropenia presenting to Karolinska University Hospital, Stockholm, Sweden during a 24-month period, were analyzed. RESULTS: A total of 142 febrile neutropenic episodes occurring in 124 hematological patients were included in the study. Bacteremia was documented in 27% of the episodes, and of these, 58% were due to Gram-positive pathogens. The most common isolates were viridans streptococci, coagulase-negative staphylococci, and Escherichia coli. Low levels of antibiotic resistance were detected. The underlying diagnosis of non-Hodgkin's lymphoma (NHL) was independently negatively associated with documented bacteremia (p < 0.01). CONCLUSIONS: The prevalence of bacteremia and the bacterial spectrum were consistent with recent Scandinavian reports. Substantially lower levels of antimicrobial resistance were registered compared to those found in other European centers. Patients with NHL were less likely to have documented bacteremia in this study.

Artemether-lumefantrine treatment failure despite adequate lumefantrine day 7 concentration in a traveller with Plasmodium falciparum malaria after returning from Tanzania.

Artemether-lumefantrine is currently first-line therapy of Plasmodium falciparum malaria in many countries. This report describes a treatment failure despite adequate drug concentrations in a traveller returning from sub-Saharan Africa. Genotyping confirmed recrudescence and suggested reduced sensitivity. Potential sub-optimal effect of artemether-lumefantrine highlights the need to follow non-immune individuals the weeks after treatment.

Characterization of early host responses in adults with dengue disease.

BACKGROUND: While dengue-elicited early and transient host responses preceding defervescence could shape the disease outcome and reveal mechanisms of the disease pathogenesis, assessment of these responses are difficult as patients rarely seek healthcare during the first days of benign fever and thus data are lacking. METHODS: In this study, focusing on early recruitment, we performed whole-blood transcriptional profiling on dengue virus PCR positive patients sampled within 72 h of self-reported fever presentation (average 43 h, SD 18.6 h) and compared the signatures with autologous samples drawn at defervescence and convalescence and to control patients with fever of other etiology. RESULTS: In the early dengue fever phase, a strong activation of the innate immune response related genes were seen that was absent at defervescence (4-7 days after fever debut), while at this second sampling genes related to biosynthesis and metabolism dominated. Transcripts relating to the adaptive immune response were over-expressed in the second sampling point with sustained activation at the third sampling. On an individual gene level, significant enrichment of transcripts early in dengue disease were chemokines CCL2 (MCP-1), CCL8 (MCP-2), CXCL10 (IP-10) and CCL3 (MIP-1α), antimicrobial peptide ß-defensin 1 (DEFB1), desmosome/intermediate junction component plakoglobin (JUP) and a microRNA which may negatively regulate pro-inflammatory cytokines in dengue infected peripheral blood cells, mIR-147 (NMES1). CONCLUSIONS: These data show that the early response in patients mimics those previously described in vitro, where early assessment of transcriptional responses has been easily obtained. Several of the early transcripts identified may be affected by or mediate the pathogenesis and deserve further assessment at this timepoint in correlation to severe disease.

Flocked nasal swab versus nasopharyngeal aspirate for detection of respiratory tract viruses in immunocompromised adults: a matched comparative study.

BACKGROUND: Several studies have compared nasal swabs to the more invasive nasopharyngeal aspirate (NPA) for detection of respiratory viruses. Mostly, the comparisons have been performed on immunocompetent children with upper respiratory tract symptoms. The results range from a relatively poor sensitivity for the swabs to an even higher sensitivity than for the NPA. We aimed to investigate the sensitivity of a flocked nasal swab (fNS) on immunocompromised adults with febrile neutropenia. METHODS: During 16 months, adults with a hematological disorder presenting with febrile neutropenia were enrolled in the study. Paired samples of the fNS and NPA were collected in the outer part of the nasal cavity and the nasopharynx, respectively. The samples were analyzed regarding a panel of 15 respiratory viruses by means of quantitative polymerase chain reaction. Furthermore, as an indirect measure of cell yield by either method, the copy number of the human beta actin gene was also determined. Cohen's kappa was calculated as a measure of agreement of the results obtained from either method. Wilcoxon signed-rank test was used for comparison of cell yield. RESULTS: A total of 98 paired samples from a total of 89 patients were collected. Twenty of the pairs had virus detected in at least one of the specimens; 11 in both, 7 in NPA only, and 2 in fNS only. For the fNS, the overall sensitivity for any virus and for rhinovirus only was 65% and 78%, respectively. NPA was significantly superior to the fNS in collecting epithelial cells. CONCLUSION: We found the overall sensitivity of 65% to be too low to replace NPA with this sampling technique in this patient category.

Parvovirus B19 infection in children with acute lymphoblastic leukemia is associated with cytopenia resulting in prolonged interruptions of chemotherapy.

BACKGROUND: Parvovirus B19 infection causes severe cytopenia and can mimic a leukemic relapse or therapy-induced cytopenia in patients with hematologic malignancies. We evaluated the complications of parvovirus B19 infection, including delays in the scheduled course of chemotherapy, in children with acute lymphoblastic leukemia (ALL). METHODS: Consecutive bone marrow samples were collected from 117 children with ALL and were analyzed for parvovirus B19 DNA by polymerase chain reaction. Clinical and laboratory data were collected from the Nordic Childhood Leukemia Registry and from medical records. RESULTS: Among the 117 children with ALL, 18 (15%) were found to be parvovirus B19 DNA positive. The infection was suspected on clinical grounds in only 1 of these 18 patients. Patients with viremia at diagnosis or during therapy for infection had lower viral loads (median viral load, 7 x 10(4) copies/mL) than did those who became viremic during maintenance therapy (median viral load, 2 x 10(8) copies/mL). The former group also had fewer clinical complications. Indeed, when parvovirus B19 DNA was present during the maintenance treatment, the number of complications (including cytopenia) increased, causing significantly longer periods without chemotherapy (median duration without chemotherapy, 59 days vs. 30 days; P < or = .05) and a higher number of blood transfusions (P = .018) in parvovirus B19 DNA-positive patients than in parvovirus B19 DNA-negative patients. CONCLUSIONS: Children with ALL who were infected with parvovirus B19 became cytopenic, leading to reduced treatment intensity and to complications during treatment. Screening for parvovirus B19 DNA by quantitative polymerase chain reaction in pediatric patients with ALL and unexplained cytopenia is suggested.

Complete Genome Sequence of a Sapporo Virus GV.2 Variant from a 2016 Outbreak of Gastroenteritis in Sweden.

During an outbreak of acute gastroenteritis in Sweden when laboratory routine diagnostics failed to detect a causative agent, Sapporo virus was detected in stool specimens using electron microscopy (M.-P. Hergens, J. Nederby Öhd, E. Alm, H. Hervius Askling, S. Helgesson, M. Insulander, N. Lagerkvist, B. Svennungsson, M. Tihane, T. Tolfvenstam, P. Follin, unpublished data). Whole-genome sequencing revealed a Sapporo virus variant clustering with genogroup V.

A genomics approach to understanding host response during dengue infection.

Dengue infection results in a wide clinical spectrum, ranging from asymptomatic, through fever (DF), to the life threatening complications haemorrhagic fever (DHF) and shock syndrome (DSS). Although we now understand that factors such as repeat infections and the type or magnitude of the host response are important in determining severity, the mechanisms of these actions remain largely unknown. Understanding this host-pathogen interaction may enable outcome prediction and new therapy options. Developments in biology now allow a 'systems approach' to be applied to this problem, utilizing whole genomes of both human and virus, in vitro and in vivo to enable a more complete picture of their interplay to be built up. We have developed a chip-based approach to viral sequencing, to increase efficiency and enable large numbers ofgenomes to be completed, together with a web-based interpretation tool. We have also applied human whole genome expression arrays (24000 genes) to characterize the types of host response made to infection and plan to investigate the role of host variation using human whole genome genetic association studies in the future. These technologies have identified novel host pathways involved in viral replication in vitro, and also host immune responses, such as the interferon signalling pathway, that are influenced by viral sequence. This data will be further refined through interlinking with similar data obtained from a large study of dengue patients, initiated in Singapore, that is able to look at the early host response to infection.

Early Dengue infection and outcome study (EDEN) - study design and preliminary findings.

INTRODUCTION: Dengue is a major public health problem in Singapore. Age-specific dengue morbidity rates are highest in the young adult population, unlike in many other Southeast Asian countries where dengue is mainly a paediatric disease. Hence, the World Health Organization (WHO) guidelines on dengue diagnosis and management which were developed using the paediatric experiences, may not be suitable for the management of adult dengue infections. MATERIALS AND METHODS: The Early DENgue (EDEN) infection and outcome study is a collaborative longitudinal study to investigate epidemiological, clinical, viral and host-specific features of early dengue-infected adults, in an effort to identify new early markers for prognostication. Patients presenting with early undifferentiated fever were included in the study. We carried out an interim analysis to look for early indicators of severe disease. RESULTS: During the period of this interim study analysis, 455 febrile patients were recruited. Of these, 133 were confirmed as acute dengue cases based on dengue-specific polymerase chain reaction (PCR) results. There were significant clinical and epidemiological differences between dengue and febrile non-dengue cases. Nine per cent of the dengue cases experienced persistent tiredness, drowsiness and loss of appetite beyond 3 weeks of illness. Quantitation of viral loads using the crossover (Ct) value of real-time RT-PCR correlated with the duration of symptoms. More than half of both primary and secondary dengue cases were hospitalised. There was no dengue-related mortality in this study. CONCLUSION: The duration of illness and prolonged symptom duration in 9% of the subjects indicate that the burden of dengue illness is substantially different from other non-dengue febrile illness in our study cohort. Our study also highlights the paucity of early prognostic markers for dengue fever in adults.

Frequent Respiratory Viral Infections in Children with Febrile Neutropenia - A Prospective Follow-Up Study.

OBJECTIVE: Febrile neutropenia is common in children undergoing chemotherapy for the treatment of malignancies. In the majority of cases, the cause of the fever is unknown. Although respiratory viruses are commonly associated with this condition, the etiologic significance of this finding remains unclear and is therefore the subject of this study. STUDY DESIGN: Nasopharyngeal aspirates were collected during 87 episodes of febrile neutropenia in children age 0-18 years, being treated at a children's oncology unit between January 2013 and June 2014. Real-time polymerase chain reaction was used to determine the presence of 16 respiratory viruses. Follow-up samples were collected from children who tested positive for one or more respiratory viruses. Rhinoviruses were genotyped by VP4/VP2 sequencing. Fisher's exact test and Mann-Whitney U test were used for group comparisons. RESULTS: At least one respiratory virus was detected in samples from 39 of 87 episodes of febrile neutropenia (45%), with rhinoviruses the most frequently detected. Follow-up samples were collected after a median of 28 days (range, 9-74 days) in 32 of the 39 virus-positive episodes. The respiratory viral infection had resolved in 25 episodes (78%). The same virus was detected at follow-up in one coronavirus and six rhinovirus episodes. Genotyping revealed a different rhinovirus species in two of the six rhinovirus infections. CONCLUSION: The frequency of respiratory viral infections in this group of patients suggests an etiologic role in febrile neutropenia. However, these findings must be confirmed in larger patient cohorts.

Discovery and Validation of Prognostic Biomarker Models to Guide Triage among Adult Dengue Patients at Early Infection.

BACKGROUND: Dengue results in a significant public health burden in endemic regions. The World Health Organization (WHO) recommended the use of warning signs (WS) to stratify patients at risk of severe dengue disease in 2009. However, WS is limited in stratifying adult dengue patients at early infection (Day 1-3 post fever), who require close monitoring in hospitals to prevent severe dengue. The aim of this study is to identify and validate prognostic models, built with differentially expressed biomarkers, that enable the early identification of those with early dengue infection that require close clinical monitoring. METHODS: RNA microarray and protein assays were performed to identify differentially expressed biomarkers of severity among 92 adult dengue patients recruited at early infection from years 2005-2008. This comprised 47 cases who developed WS after first presentation and required hospitalization (WS+Hosp), as well as 45 controls who did not develop WS after first presentation and did not require hospitalization (Non-WS+Non-Hosp). Independent validation was conducted with 80 adult dengue patients recruited from years 2009-2012. Prognostic models were developed based on forward stepwise and backward elimination estimation, using multiple logistic regressions. Prognostic power was estimated by the area under the receiver operating characteristic curve (AUC). RESULTS: The WS+Hosp group had significantly higher viral load (P<0.001), lower platelet (P<0.001) and lymphocytes counts (P = 0.004) at early infection compared to the Non-WS+Non-Hosp group. From the RNA microarray and protein assays, the top single RNA and protein prognostic models at early infection were CCL8 RNA (AUC:0.73) and IP-10 protein (AUC:0.74), respectively. The model with CCL8, VPS13C RNA, uPAR protein, and with CCL8, VPS13C RNA and platelets were the best biomarker models for stratifying adult dengue patients at early infection, with sensitivity and specificity up to 83% and 84%, respectively. These results were tested in the independent validation group, showing sensitivity and specificity up to 96% and 54.6%, respectively. CONCLUSIONS: At early infection, adult dengue patients who later presented WS and require hospitalization have significantly different pathophysiology compared with patients who consistently presented no WS and / or require no hospitalization. The molecular prognostic models developed and validated here based on these pathophysiology differences, could offer earlier and complementary indicators to the clinical WHO 2009 WS guide, in order to triage adult dengue patients at early infection.

Slow clearance of human parvovirus B19 viremia following acute infection.

Parvovirus B19 is a common, clinically significant pathogen. Reassessment of the viral kinetics after acute infection showed that the virus is not rapidly cleared from healthy hosts, despite early resolution of symptoms. These findings challenge our current conception of the virus' pathogenesis and have implications for the management of the infection.

Prolonged activation of virus-specific CD8+T cells after acute B19 infection.

BACKGROUND: Human parvovirus B19 (B19) is a ubiquitous and clinically significant pathogen, causing erythema infectiosum, arthropathy, transient aplastic crisis, and intrauterine fetal death. The phenotype of CD8+ T cells in acute B19 infection has not been studied previously. METHODS AND FINDINGS: The number and phenotype of B19-specific CD8+ T cell responses during and after acute adult infection was studied using HLA-peptide multimeric complexes. Surprisingly, these responses increased in magnitude over the first year post-infection despite resolution of clinical symptoms and control of viraemia, with T cell populations specific for individual epitopes comprising up to 4% of CD8+ T cells. B19-specific T cells developed and maintained an activated CD38+ phenotype, with strong expression of perforin and CD57 and downregulation of CD28 and CD27. These cells possessed strong effector function and intact proliferative capacity. Individuals tested many years after infection exhibited lower frequencies of B19-specific cytotoxic T lymphocytes, typically 0.05%-0.5% of CD8+ T cells, which were perforin, CD38, and CCR7 low. CONCLUSION: This is the first example to our knowledge of an "acute" human viral infection inducing a persistent activated CD8+ T cell response. The likely explanation--analogous to that for cytomegalovirus infection--is that this persistent response is due to low-level antigen exposure. CD8+ T cells may contribute to the long-term control of this significant pathogen and should be considered during vaccine development.

High frequency of parvovirus B19 DNA in bone marrow samples from rheumatic patients.

BACKGROUND: Human parvovirus B19 (B19) polymerase chain reaction (PCR) is now a routine analysis and serves as a diagnostic marker as well as a complement or alternative to B19 serology. The clinical significance of a positive B19 DNA finding is however dependent on the type of tissue or body fluid analysed and of the immune status of the patient. OBJECTIVES: To analyse the clinical significance of B19 DNA positivity in bone marrow samples from rheumatic patients. STUDY DESIGN: Parvovirus B19 DNA was analysed in paired bone marrow and serum samples by nested PCR technique. Serum was also analysed for B19-specific IgG and IgM antibodies and the results were compared with clinical and epidemiological data. RESULTS AND CONCLUSIONS: B19 IgG was found in 41 of 50 patients (82%) whereas none was B19 IgM positive. The serologic evaluation showed that none of the patients had acute B19 infection. However, B19 DNA was detected by PCR in 13 of 50 (26%) bone marrow samples from these patients indicating a high frequency of persistent infection compared with previous reports of patient groups and healthy controls. In the study, 22 patients had rheumatoid arthritis (RA) and 7 of these RA patients were B19 DNA positive in bone marrow. Rheumatoid factor was positive in 4 of the 7 B19 DNA positive RA patients as compared with Rheumatoid factor positivity in all of the 15 B19 DNA negative RA patients. Erosive arthritis in X-ray was less common in the B19 DNA positive group than in the B19 DNA negative group. A high frequency of parvovirus B19 DNA was thus detected in bone marrow samples in rheumatic patients. The clinical data does not support a direct association between B19 PCR positivity and rheumatic disease manifestation. Therefore, the clinical significance of B19 DNA positivity in bone marrow samples from rheumatic patients must be interpreted with caution.

Parvovirus B19 capsid protein VP2 inhibits hematopoiesis in vitro and in vivo: implications for therapeutic use.

OBJECTIVE: To evaluate the capacity of parvovirus B19 capsid protein VP2 to inhibit hematopoiesis in vitro and in vivo. If effective, a VP2-derived construct may have therapeutic and prophylactic utility in diseases associated to overproduction of hematopoietic cells. METHODS: The effect on hematopoiesis in vitro of recombinant VP2, intact and enzymatically fragmented, was evaluated in a colony formation assay, using cells from fetal liver and macaque bone marrow. VP2 was also administered intravenously in macaques and hematological parameters as well as the ex vivo colony formation were assayed during a follow-up period of 33 days. RESULTS: VP2 inhibited BFU-E colony formation by about 55%. CFU-GM and CFU-GEMM colony formation was also affected. Fragmented VP2 retained the inhibitory effect. The ex vivo colony-forming capacity of macaque bone marrow cells was lower in animals that received VP2 injections, and a drop in hematocrit values was noted in one animal. CONCLUSION: VP2 has an inhibitory effect on hematopoiesis in vitro and in vivo. An active region within VP2 is implied, which would be a strong candidate for use as a medicament in diseases such as polycytemia vera.

Active, fulminant, lethal myocarditis associated with parvovirus B19 infection in an infant.

We report a case of fulminant myocarditis in an 11-month-old female infant who had no other clinical signs of parvovirus infection. The patient presented with severe respiratory distress and died in sudden cardiac arrest 3 h after admission. The clinical presentation was similar to that of an asthmatic attack. Autopsy revealed signs of acute lymphocytic myocarditis. Parvovirus DNA was demonstrated by polymerase chain reaction (PCR) analysis of tissue sections obtained from the heart, lungs, liver, kidneys, and spleen. Transmission electron microscopy of myocardial tissue showed crystalline arrays with the appearance of parvovirus. The results of immunohistochemical analysis for the detection of parvovirus antigens were negative, and no viral inclusions were demonstrable. We suggest that the current diagnostic procedure underestimates the prevalence of parvovirus-associated myocarditis. PCR analysis should be used as a complement in suspected cases, to enhance the rate of detection of the infection and to reach a correct diagnosis.

Revised clinical presentation of parvovirus B19-associated intrauterine fetal death.

Adverse pregnancy outcome due to human parvovirus B19 (hereafter referred to as "parvovirus B19") has been characterized, in numerous reports, as an event that occurs during the first and second trimesters and is strongly associated with symptoms of fetal hydrops. Recent findings have indicated that parvovirus B19-associated intrauterine fetal death (IUFD) is also a problem in late gestation, although its clinical presentation is aberrant, lacking signs of fetal hydrops. We outlined the clinical presentation and assessed the frequency of parvovirus B19 infection in a retrospective analysis of 92 unselected cases of IUFD that occurred during or after gestational week 22. By polymerase chain reaction, parvovirus B19 DNA was detected in 13 (14%) of the 92 cases. Only 2 of the parvovirus B19 DNA-positive cases were hydropic, both representing early IUFDs. This finding indicates that parvovirus B19-associated IUFD in late gestation is a common finding and that hydropic presentation is rare. This knowledge may contribute to a reduction in the number of unexplained cases of IUFD.