Rates and risk factors of severe respiratory syncytial virus infection in 2008-2016 compared with 1986-1998.

AIM: Since the introduction in 1979 of rapid testing using immunofluorescence, we have collected information about children hospitalised for confirmed respiratory syncytial virus (RSV) infection in the northern Stockholm area. We here report hospitalisation rates, risk factors and complications in 2008-2016 compared with 1986-1998. METHODS: Microbiological laboratory reports and retrospective chart review. Comparison of the two periods was complicated by changing testing routines, with a more sensitive method and increased testing of older children in the late period. RESULTS: In infants, there was an 12.3% increase in the population-based rate of hospital admission for RSV infection from 12.2 to 13.7/1000. Including all children <5 years, there was a 48% increase from 2.7 to 4.0/1000. The median length of stay remained unchanged at 3 days. The need of intensive care decreased in healthy infants but remained high in older children with comorbidity. CONCLUSION: Considering the changed diagnosis routines, we believe that the rate of hospital admission of infants for RSV infection was unchanged throughout the observed years. The increased rates of older children with confirmed RSV likely resulted from increased testing of children with risk factors for a complicated course.

Outbreak of enterovirus D68 of the new B3 lineage in Stockholm, Sweden, August to September 2016.

We report an enterovirus D68 (EV-D68) outbreak in Stockholm Sweden in 2016. Between 22 August and 25 September EV-D68 was detected in 74/495 respiratory samples analysed at the Karolinska University Hospital. During the peak week, 30/91 (33%) samples were EV-D68 positive. Viral protein (VP)P4/VP2 sequencing revealed that cases were caused by B3 lineage strains. Forty-four (59%) EV-D68-positive patients were children aged ≤ 5 years. Ten patients had severe respiratory or neurological symptoms and one died.

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.

Children with multiple viral respiratory infections are older than those with single viruses.

AIM: To study the clinical impact of multiple viral respiratory infections compared to single infections. METHODS: Demographic data from 37 multiple infection periods in children <5 years of age were compared to data from 193 episodes with single infections. Clinical data derived from patient records of the multiple infection episodes were further compared to data from 93 matched control episodes with single infections. RESULTS: The mean age of patients with multiple viral findings was 12.7 months, compared to 5.7 months for those with single findings (p < 0.01). Wheezing was the most common diagnosis in both groups, except among children who were only infected with the coronavirus. No differences were found regarding duration of hospitalisation, oxygen treatment or admittance to the intensive care unit. CONCLUSION: Children with multiple viral findings in their respiratory secretions were older than those with a single detected virus. Otherwise, no major differences in comorbidity, presentation or clinical outcome were observed between the two groups.

Reduction of rotavirus as a cause of nosocomial diarrhoea in northern Stockholm after introducing the rotavirus vaccine.

Background: Vaccination against rotavirus was offered in Stockholm to children born on 1 March 2014 and onwards with 85% coverage after two years. We investigated changes in nosocomial diarrhoea 2010-2018 in children admitted to Astrid Lindgren Children's Hospital, Stockholm, Sweden. Methods: We retrospectively identified cases from diagnostic and virology department registers. Complications and chronic medical conditions were retrieved from the case records. Children <18 years of age who developed diarrhoea ≥48 h after admission for another diagnosis and had a faecal sample submitted to the virology department were included. Results: There were 474 episodes of nosocomial diarrhoea. Of these, 401 (85%) occurred in children with chronic medical conditions. In children <5 years the rates of nosocomial rotavirus gastroenteritis, with 95% confidence intervals, significantly decreased from 0.34 (0.25-0.45) per 100 admissions prevaccination to 0.09 (0.04-0.17) postvaccination and from 0,66 (0.48-0.88) to 0.16 (0.07-0.30) cases per 1000 hospital days. Postvaccination norovirus became the most frequent pathogen. Virus-positive cases were more common in young children and in winter months. Conclusions: Before the initiation of rotavirus vaccination, norovirus and rotavirus were equally common causes of nosocomial diarrhoea. Postvaccination, rotavirus was reduced by approximately 75% while the frequency of other viruses did not change.

All-cause gastroenteritis hospitalisations of children decreased after the introduction of rotavirus vaccine in Stockholm.

BACKGROUND: In Stockholm, Sweden, rotavirus vaccination was offered to children born after 1 March 2014. Our aim was to describe rates of hospitalisation due to community-acquired gastroenteritis before and after the introduction of the vaccine, and aetiology, underlying medical conditions and complications in admitted children. METHODS: We retrospectively included patients from our catchment area hospitalised with a diagnosis of gastroenteritis during ten infection seasons 2008/2009-2017/2018, whereof six seasons prevaccination and four seasons postvaccination. We studied virus detection data and the patients' medical records. RESULTS: We included 3718 episodes in 3513 children. In 2967 (80%), stools were tested with virus isolation, ELISA, PCR, or bacterial culture; 479 (16%) tested negative. The incidence rates, with 95% confidence intervals, for children <5 years hospitalised for rotavirus gastroenteritis were 2.9 (2.8-3.1) per 1000 person-years prevaccination and 0.65 (0.56-0.74) postvaccination, for a rate ratio (RR) of 0.22 (0.19-0.26, p < .001). The rates for all-cause gastroenteritis were 5.6 (5.4-5.9) prevaccination and 2.5 (2.3-2.7) postvaccination, RR 0.45 (0.42-0.50, p < .001). In 5-17-year-old children norovirus dominated with little change over time. Of patients <5 years, those with underlying conditions constituted a larger proportion postvaccination than prevaccination (30.7% vs. 24.2%, p < .001). A complication other than dehydration, most commonly seizures, arose in 8.8% of the patients <5 years prevaccination and 11.4% postvaccination (p < .05). CONCLUSIONS: Rotavirus vaccination reduced the number of children <5 years requiring hospital care for gastroenteritis. We saw no replacement of rotavirus by other viruses.

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.

Occurrence of pharyngeal Chlamydia trachomatis is uncommon in patients with a suspected or confirmed genital infection.

OBJECTIVE: To evaluate how common pharyngeal Chlamydia trachomatis (CT) is among mainly heterosexual women and men with a confirmed or a highly suspicious genital infection having had recent unprotected active oral sex. DESIGN: Prospective observational study. SETTING: Out-patient clinics for sexually transmitted infections in Stockholm. POPULATION: A total of 143 women and 138 men with a confirmed or suspected genital CT infection and a history of active oral sex. METHODS: Pharyngeal samples from men and women in the study population were analyzed for the presence of CT. MAIN OUTCOME MEASURES: Number of positive CT in pharyngeal samples in relation to positive CT in genital samples. RESULTS: Of the women, 9/128 (7.0%) were positive in the pharyngeal samples. None were exclusively positive in the pharynx. Three of 110 men (2.7%) had pharyngeal involvement. One man was positive in the pharynx as well as in the urine sample, and two men were exclusively pharyngeal CT positive. CONCLUSIONS: The finding of CT in the pharynx is not common in spite of the presence of a genital infection and a history of active oral sex.

Development and implementation of a molecular diagnostic platform for daily rapid detection of 15 respiratory viruses.

Acute respiratory tract infections are caused by a large number of viruses. Diagnostic methods have until recently been available only for a limited number of these viruses. With the objective to achieve sensitive assays for all respiratory viruses, a rational workflow in the laboratory, and a short turn-around time, a real-time PCR diagnostic platform for daily rapid detection of 15 respiratory viruses was developed. The system was evaluated on 585 stored nasopharyngeal aspirates from hospitalized children. Previous analysis by immunofluorescence and virus isolation identified viruses in 37% of the samples while the new PCR diagnostic panel detected 57% virus positive samples. The new platform was introduced in the laboratory in October 2007 and has then fully replaced the standard immunofluorescence assay for rapid detection of viruses and virus isolation.

Repeat infection with Chlamydia trachomatis: a prospective cohort study from an STI-clinic in Stockholm.

BACKGROUND: Infection with genital Chlamydia trachomatis (Ct) is the most common notifiable sexually transmitted infection (STI) in Sweden. A mutated Chlamydia, nvCT, has contributed to the increase. The occurrence of repeat infections is not investigated in Sweden. The current paper presents the study protocol for the first Swedish clinical investigation of repeat Chlamydial infection. The concern of the study is whether a Chlamydia infection at inclusion indicates an increased risk for Chlamydia at follow-up after 6-8 months, gender-specific risk factors for and clinical presentation of repeat infections. METHODS AND DESIGN: Sesam City is a drop-in clinic in the city centre of Stockholm. Patients 20 years and older are admitted. During 2007, the clinic had 15,000 visits, 60% made by men. In December 2007, a cohort study began, and data collection was finished in April 2009. A total of 2,813 study participants aged 20-39 years were recruited. Data collection included an anonymous self-administered paper-and-pen questionnaire on sexual behaviour, reproductive health and history of Chlamydia, and condom use. Chlamydia tests were performed by self-sampled specimens, analyzed by the ProbeTec (Becton Dickinson) method, Ct-positive specimens also analyzed with a nvCT-specific method. Data from medical records were summarized in clinical report forms. Patients positive for Chlamydia were retested 4 weeks after treatment. Contact tracing covered sexual contacts during the last 12 months. At follow-up 6-8 months after inclusion, Chlamydia tests were performed, and a new questionnaire and CRF completed. DISCUSSION: A STI-clinic-based prospective cohort study allowed us to survey 2813 adult patients. The collected data will provide gender-specific information on the occurrence of and risk for repeat Chlamydia infection, the occurrence of nvCT, and clinical data and information on sexual behaviour and reproductive health, risk-taking and condom use.

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.

Coexistence of two clades of enterovirus D68 in pediatric Swedish patients in the summer and fall of 2014.

In 2014, an outbreak of enterovirus D68 (EV-D68) was observed in North America, with cases of severe respiratory illness and a possible etiological link to cases of acute flaccid paralysis. EV-D68 has also been reported from European countries, but no data from Sweden are available. This study investigated respiratory specimens collected during July-October 2014 from 30 Swedish children aged 0-9 years who were positive for enterovirus and/or rhinovirus in routine clinical PCR. Seven samples were typed as EV-D68 by VP4/VP2 sequencing. Two genetically distinct EV-D68 variants coexisted. Six viruses belonged to clade B, the variant involved in the North American outbreak, and one virus belonged to clade A. Respiratory illness was the major symptom among EV-D68 infected patients and all fully recovered. This is the first report of EV-D68 in Sweden. Considering the current epidemiological situation, genotyping and specific EV-D68 testing should be considered in patients with severe respiratory illness who test positive for enterovirus or rhinovirus in routine diagnostics.

Clinical utility of PCR for common viruses in acute respiratory illness.

BACKGROUND: Acute respiratory illness (ARI) accounts for a large proportion of all visits to pediatric health facilities. Quantitative real-time polymerase chain reaction (qPCR) analyses allow sensitive detection of viral nucleic acids, but it is not clear to what extent specific viruses contribute to disease because many viruses have been detected in asymptomatic children. Better understanding of how to interpret viral findings is important to reduce unnecessary use of antibiotics. OBJECTIVE: To compare viral qPCR findings from children with ARI versus asymptomatic control subjects. METHODS: Nasopharyngeal aspirates were collected from children aged ≤5 years with ARI and from individually matched, asymptomatic, population-based control subjects during a noninfluenza season. Samples were analyzed by using qPCR for 16 viruses. RESULTS: Respiratory viruses were detected in 72.3% of the case patients (n = 151) and 35.4% of the control subjects (n = 74) (P = .001). Rhinovirus was the most common finding in both case patients and control subjects (47.9% and 21.5%, respectively), with a population-attributable proportion of 0.39 (95% confidence interval: 0.01 to 0.62). Metapneumovirus, parainfluenza viruses, and respiratory syncytial virus were highly overrepresented in case patients. Bocavirus was associated with ARI even after adjustment for coinfections with other viruses and was associated with severe disease. Enterovirus and coronavirus were equally common in case patients and control subjects. CONCLUSIONS: qPCR detection of respiratory syncytial virus, metapneumovirus, or parainfluenza viruses in children with ARI is likely to be causative of disease; detection of several other respiratory viruses must be interpreted with caution due to high detection rates in asymptomatic children.

Respiratory viruses in hospitalized children with influenza-like illness during the h1n1 2009 pandemic in Sweden [corrected].

BACKGROUND: The swine-origin influenza A(H1N1)pdm09 pandemic of 2009 had a slower spread in Europe than expected. The human rhinovirus (HRV) has been suggested to have delayed the pandemic through viral interference. The importance of co-infections over time during the pandemic and in terms of severity of the disease needs to be assessed. OBJECTIVE: The aim of this study was to investigate respiratory viruses and specifically the presence of co-infections with influenza A(H1N1)pdm09 (H1N1) in hospitalized children during the H1N1 pandemic. A secondary aim was to investigate if co-infections were associated with severity of disease. METHODS: A retrospective study was performed on 502 children with influenza-like illness admitted to inpatient care at a pediatric hospital in Stockholm, Sweden during the 6 months spanning the H1N1 pandemic in 2009. Respiratory samples were analyzed for a panel of 16 viruses by real-time polymerase chain reaction. RESULTS: One or more viruses were detected in 61.6% of the samples. Of these, 85.4% were single infections and 14.6% co-infections (2-4 viruses). The number of co-infections increased throughout the study period. H1N1 was found in 83 (16.5%) children and of these 12 (14.5%) were co-infections. HRV and H1N1 circulated to a large extent at the same time and 6.0% of the H1N1-positive children were also positive for HRV. There was no correlation between co-infections and severity of disease in children with H1N1. CONCLUSIONS: Viral co-infections were relatively common in H1N1 infected hospitalized children and need to be considered when estimating morbidity attributed to H1N1. Population-based longitudinal studies with repeated sampling are needed to improve the understanding of the importance of co-infections and viral interference.

Respiratory viruses, a common microbiological finding in neutropenic children with fever.

BACKGROUND: Febrile neutropenia is a common complication in children undergoing chemotherapy for malignancies. A microbial agent is only identified in 15-30% of the fever episodes and corresponds mostly to bacterial findings. OBJECTIVE: To investigate viral infections as possible etiologic agents in episodes of febrile neutropenia. STUDY DESIGN: Nasopharyngeal aspirates (NPAs) from patients presenting with neutropenic fever at two pediatric oncology wards in Sweden and Australia were analyzed with a conventional virus-diagnostic approach and RT-PCR. Coupled blood samples were analyzed for the detection of CMV, EBV, adenovirus and erythrovirus. Bacterial blood culture was performed routinely. RESULTS: Conventional virus-diagnostic approach coupled to routinely performed bacterial analyzes revealed an infectious agent in 29% compared to 60% when using PCR. By adding PCR, a viral pathogen was detected in 46% of the NPAs and in 4% of the blood samples collected. In half of the patients with bacteremia, respiratory tract viruses were co-detected. CONCLUSION: Respiratory viruses were frequently detected in NPAs suggesting a significant role of viral infections in children presenting with neutropenic fever. The meaning of these findings needs to be further evaluated but has the potential to individualize infection treatment and to reduce the extensive use of antibiotics in immunocompromised children with neutropenia.

High occurrence of a new variant of Chlamydia trachomatis escaping diagnostic tests among STI clinic patients in Stockholm, Sweden.

BACKGROUND: In 2006, a genetic variant of Chlamydia trachomatis not detectable with the most commonly used diagnostic tests was identified. Initial reports suggested that as many as 10% to 13% of all chlamydia cases would have remained undiagnosed. The aim of the study was to find the occurrence and clinical findings of this genetic variant among a high-risk population in Stockholm, Sweden. METHODS: Samples were analyzed using the Cobas TaqMan CT test (Roche Diagnostics). To detect the new variant, an additional PCR-analysis, artus C. trachomatis LC MOMP PCR Kit (Qiagen) was performed on all negative samples. Positive results in the artus test were confirmed by a mutant specific PCR. Clinical data were retrospectively collected from medical records. RESULTS: Among 1009 samples analyzed, 115 were positive for C. trachomatis and among those, 27 were found to belong to the genetic altered strain. This variant constituted 23% of all chlamydia cases diagnosed, and 29% were found in the age group 20 to 29 years. Women with the new variant were younger and had more often performed another chlamydia test within the previous 6 months compared with those infected with the wild type. CONCLUSION: These results indicate that a large number of sexually active individuals might be infected despite a negative chlamydia test, thus facilitating a rapid transmission of the new variant. Accordingly, it is of great importance to be aware of limitations of the diagnostic methods used.