Impact analysis of rotavirus vaccination in various geographic regions in Western Europe.

BACKGROUND: Universal mass vaccination (UMV) against rotavirus has been implemented in many but not all European countries. This study investigated the impact of UMV on rotavirus incidence trends by comparing European countries with UMV: Belgium, England/Wales and Germany versus countries without UMV: Denmark and the Netherlands. METHODS: For this observational retrospective cohort study, time series data (2001-2016) on rotavirus detections, meteorological factors and population demographics were collected. For each country, several meteorological and population factors were investigated as possible predictors of rotavirus incidence. The final set of predictors were incorporated in negative binomial models accounting for seasonality and serial autocorrelation, and time-varying incidence rate ratios (IRR) were calculated for each age group and country separately. The overall vaccination impact two years after vaccine implementation was estimated by pooling the results using a random effects meta-analyses. Independent t-tests were used to compare annual epidemics in the pre-vaccination and post-vaccination era to explore any changes in the timing of rotavirus epidemics. RESULTS: The population size and several meteorological factors were predictors for the rotavirus epidemiology. Overall, we estimated a 42% (95%-CI 23;56%) reduction in rotavirus incidence attributable to UMV. Strongest reductions were observed for age-groups 0-, 1- and 2-years (IRR 0.47, 0.48 and 0.63, respectively). No herd effect induced by UMV in neighbouring countries was observed. In all UMV countries, the start and/or stop and corresponding peak of the rotavirus season was delayed by 4-7 weeks. CONCLUSIONS: The introduction of rotavirus UMV resulted in an overall reduction of 42% in rotavirus incidence in Western European countries two years after vaccine introduction and caused a change in seasonal pattern. No herd effect induced by UMV neighbouring countries was observed for Denmark and the Netherlands.

Detection of norovirus infections in Denmark, 2011-2018.

Norovirus (NoV) infections occur very frequently yet are rarely diagnosed. In Denmark, NoV infections are not under surveillance. We aimed to collect and describe existing laboratory-based NoV data. National NoV laboratory data were collected for 2011-2018, including information on patient identification number, age and sex, requesting physician, analysis date and result. We defined positive patient-episodes by using a 30-day time window and performed descriptive and time series analysis. Diagnostic methods used were assessed through a survey. We identified 15 809 patient-episodes (11%) out of 142 648 tested patients with an increasing trend, 9366 in 2011 vs. 32 260 in 2018. This corresponded with a gradual introduction of polymerase chain reaction analysis in laboratories. The highest positivity rate was in patients aged <5 years (15%) or >85 years (17%). There was a large difference in test performance over five Danish geographical regions and a marked seasonal variation with peaks from December to February. This is the first analysis of national NoV laboratory data in Denmark. A future laboratory-based surveillance system may benefit public health measures by describing trend, burden and severity of seasons and possibly pinpoint hospital outbreaks.

A European multicentre evaluation of detection and typing methods for human enteroviruses and parechoviruses using RNA transcripts.

Polymerase chain reaction (PCR) detection has become the gold standard for diagnosis and typing of enterovirus (EV) and human parechovirus (HPeV) infections. Its effectiveness depends critically on using the appropriate sample types and high assay sensitivity as viral loads in cerebrospinal fluid samples from meningitis and sepsis clinical presentation can be extremely low. This study evaluated the sensitivity and specificity of currently used commercial and in-house diagnostic and typing assays. Accurately quantified RNA transcript controls were distributed to 27 diagnostic and 12 reference laboratories in 17 European countries for blinded testing. Transcripts represented the four human EV species (EV-A71, echovirus 30, coxsackie A virus 21, and EV-D68), HPeV3, and specificity controls. Reported results from 48 in-house and 15 commercial assays showed 98% detection frequencies of high copy (1000 RNA copies/5 µL) transcripts. In-house assays showed significantly greater detection frequencies of the low copy (10 copies/5 µL) EV and HPeV transcripts (81% and 86%, respectively) compared with commercial assays (56%, 50%; P = 7 × 10-5 ). EV-specific PCRs showed low cross-reactivity with human rhinovirus C (3 of 42 tests) and infrequent positivity in the negative control (2 of 63 tests). Most or all high copy EV and HPeV controls were successfully typed (88%, 100%) by reference laboratories, but showed reduced effectiveness for low copy controls (41%, 67%). Stabilized RNA transcripts provide an effective, logistically simple and inexpensive reagent for evaluation of diagnostic assay performance. The study provides reassurance of the performance of the many in-house assay formats used across Europe. However, it identified often substantially reduced sensitivities of commercial assays often used as point-of-care tests.

Effectiveness of maternal immunization with trivalent inactivated influenza vaccine in pregnant women and their infants.

BACKGROUND: In randomized trials, it has been found that maternal influenza vaccination reduces influenza infections in both women and their infants. However, these trials have been performed in low-resource settings, and evidence from high-resource settings is limited. METHODS: Nested within a register-based cohort of all women giving birth in Denmark between 2010 and 2016 (n = 357 810 births), we conducted two case-control studies using a test-negative design of all pregnant women and their infants, respectively, tested for influenza virus with reverse transcriptase-polymerase chain reaction. Influenza virus-positive cases were matched (1:1) with influenza virus-negative controls for calendar time and (gestational or infant) age at testing. The effectiveness of maternal immunization with trivalent inactivated influenza vaccine was estimated from the odds ratios of vaccination among cases versus controls using logistic regression with adjustment for potential confounders. RESULTS: Among 313 pregnant women positive for influenza virus, 16 (5.1%) were vaccinated; by comparison, 34 (10.9%) pregnant women were vaccinated among 313 matched influenza virus-negative controls. The effectiveness of vaccination against laboratory-confirmed influenza infection in pregnant women was 63.9% [95% confidence interval (CI), 29.1 to 81.6]. Among 460 infants positive for influenza virus, 23 (5.0%) were offspring of women vaccinated during pregnancy; by comparison, 52 (11.3%) infants were the offspring of women vaccinated during pregnancy among 460 matched influenza virus-negative controls. The effectiveness of maternal vaccination against laboratory-confirmed influenza infection in infants younger than 6 months of age was 56.8% (95% CI, 25.0 to 75.1). CONCLUSIONS: Seasonal trivalent inactivated influenza vaccination in pregnancy was associated with a statistically significant reduced risk of laboratory-confirmed influenza infections in pregnant women and their infants in a high-resource setting.

No evidence of enteric viral involvement in the new neonatal porcine diarrhoea syndrome in Danish pigs.

BACKGROUND: The aim of this study was to investigate whether the syndrome New Neonatal Porcine Diarrhoea Syndrome (NNPDS) is associated with a viral aetiology. Four well-managed herds experiencing neonatal diarrhoea and suspected to be affected by NNPDS were included in a case-control set up. A total of 989 piglets were clinically examined on a daily basis. Samples from diarrhoeic and non-diarrhoeic piglets at the age of three to seven days were selected for extensive virological examination using specific real time polymerase chain reactions (qPCRs) and general virus detection methods. RESULTS: A total of 91.7% of the animals tested positive by reverse transcription qPCR (RT-qPCR) for porcine kobuvirus 1 (PKV-1) while 9% and 3% were found to be positive for rotavirus A and porcine teschovirus (PTV), respectively. The overall prevalence of porcine astrovirus (PAstV) was 75% with 69.8% of the PAstV positive pigs infected with PAstV type 3. No animals tested positive for rotavirus C, coronavirus (TGEV, PEDV and PRCV), sapovirus, enterovirus, parechovirus, saffoldvirus, cosavirus, klassevirus or porcine circovirus type 2 (PCV2). Microarray analyses performed on a total of 18 animals were all negative, as were eight animals examined by Transmission Electron Microscopy (TEM). Using Next Generation de novo sequencing (de novo NGS) on pools of samples from case animals within all herds, PKV-1 was detected in four herds and rotavirus A, rotavirus C and PTV were detected in one herd each. CONCLUSIONS: Our detailed analyses of piglets from NNPDS-affected herds demonstrated that viruses did not pose a significant contribution to NNPDS. However, further investigations are needed to investigate if a systemic virus infection plays a role in the pathogenesis of NNPDS.

Emergence of enterovirus D68 in Denmark, June 2014 to February 2015.

From June 2014 through February 2015, respiratory samples from 130 Danish patients were screened for enterovirus D68 (EV-D68). Fourteen EV-D68 cases were detected, of which 12 presented with respiratory symptoms, and eight had known underlying disease. The median age of EV-D68 cases was three years (interquartile range: 0­30 years). Acute flaccid paralysis (AFP) was not detected although Danish EV-D68 strains showed > 98% nt identity with EV-D68-strains from AFP cases from the United States and France.

Evaluation of the impact of a simple hand-washing and water-treatment intervention in rural health facilities on hygiene knowledge and reported behaviours of health workers and their clients, Nyanza Province, Kenya, 2008.

Many clinics in rural western Kenya lack access to safe water and hand-washing facilities. To address this problem, in 2005 a programme was initiated to install water stations for hand washing and drinking water in 109 health facilities, train health workers on water treatment and hygiene, and motivate clients to adopt these practices. In 2008, we evaluated this intervention's impact by conducting observations at facilities, and interviewing staff and clients about water treatment and hygiene. Of 30 randomly selected facilities, 97% had water stations in use. Chlorine residuals were detectable in at least one container at 59% of facilities. Of 164 interviewed staff, 79% knew the recommended water-treatment procedure. Of 298 clients, 45% had received training on water treatment at a facility; of these, 68% knew the recommended water-treatment procedure. Use of water stations, water treatment, and client training were sustained in some facilities for up to 3 years.

Emergence of enterovirus 71 C4a in Denmark, 2009 to 2013.

Enterovirus (EV) 71 has emerged as a primary cause of severe neurologic enterovirus infection in the aftermath of the global polio eradication effort. Eleven subgenotypes of EV71 exist, the C4 subgenotype being associated with large outbreaks in Asia with high mortality rates. This subgenotype has rarely been reported in Europe. In the period between 1 January 2009 and 31 December 2013 a total of 1,447 EV positive samples from 1,143 individuals were sent to the Statens Serum Institute (SSI), and 938 samples from 913 patients were genotyped at the Danish National World Health Organization Reference laboratory for Poliovirus at SSI. Echovirus 6 (E06) (n=141 patients), echovirus 30 (E30) (n=114), coxsackievirus A6 (CA06) (n=96) and EV71 (n=63) were the most prevalent genotypes. We observed a shift in circulating EV71 subgenotypes during the study period, with subgenotype C4 dominating in 2012. A total of 34 EV71 patients were found to be infected with strains of the C4 subgenotype, and phylogenetic analysis revealed that they belonged to the C4a lineage. In our study, the proportions of cases with cerebral and/or sepsis-like symptoms were similar in those affected by C4a (19/34) and those with C1 and C2 (15/35). The majority (n=30) of the 34 EV71 C4 cases were children≤5 years of age, and males (n=22) were over-represented. Continued EV surveillance is required to monitor the spread of EV71 C4 in Denmark and the rest of Europe.

Human group A rotavirus infections in children in Denmark: detection of reassortant G9 strains and zoonotic P[14] strains.

One of the leading causes of severe childhood gastroenteritis are group A rotaviruses, and they have been found to be associated with ∼40% of the annual gastroenteritis-associated hospitalizations in young Danish children <5years of age (Fischer et al., 2011). In this study, we investigated the diversity of rotavirus strains circulating among young children <5years of age, presenting with gastroenteritis disease either at the general practitioner or in the hospital, during the period 2009-2013. A total of 831 rotavirus positive stool samples were genotyped in the study period, and the majority of samples (74%) were from hospitalized children. G and P genotypes were successfully determined for 826 of samples, with G1P[8] being the most commonly detected genotype. Detection of G1 showed a decreasing trend over time, and an inverse trend was seen for the emerging G9P. The common human genotypes (G1/G3/G4/G9P[8] and G2P[4]) were detected in the majority of samples (n=733, 88.2%). Rare genotype combinations such as G6P[14] were detected in <1% of samples. Rare genotype strains and strains which failed to amplify in genotyping RT-PCR were subjected to genetic characterization by sequencing one or all of the following genes; VP7, VP4, VP6 and NSP4. Sequences of sufficient length and quality were available for all 4 genes for 28 strains. Phylogenetic analysis revealed that reassortant G9P[4] strains circulated with 3 different genotype combinations. As rotavirus vaccines are not widely used in Denmark or its neighboring countries, the diversity of rotavirus strains identified in this study most likely reflects naturally occurring selection pressures and viral evolution.

Emergence of a new recombinant Sydney 2012 norovirus variant in Denmark, 26 December 2012 to 22 March 2013.

We report here new recombinants between the norovirus II.4 Sydney 2012 and the II.4 New Orleans 2009 variants. This demonstrates that the II.4 Sydney 2012 variant is undergoing further diversification and suggests a potential for rapid evolution. We also provide primers, which allow the amplification and sequencing of both the current New Orleans 2009 and Sydney 2012 variants and the new II.4 New Orleans 2009/II.4 Sydney 2012 recombinants for more accurate surveillance and transmission tracking.

Low vaccine effectiveness against influenza A(H3N2) virus among elderly people in Denmark in 2012/13--a rapid epidemiological and virological assessment.

In Denmark, the 2012/13 influenza season has been dominated by influenza A(H3N2). We estimated the vaccine effectiveness (VE) of the trivalent influenza vaccine by linking national registers in a test-negative case-control study of patients tested for influenza aged ≥65 years. The adjusted VE against laboratory-confirmed influenza A and B was -11% (95% CI: -41 to 14) and 69% (95% CI: 26 to 87), respectively. Genetic characterisation of the influenza A(H3N2) viruses indicated genetic drift, with seven substitutions at key antigenic sites.

Characterization of rotavirus strains in a Danish population: high frequency of mixed infections and diversity within the VP4 gene of P[8] strains.

We characterized the G and P types from 162 rotavirus-positive stool specimens collected from 162 persons in Denmark (134 children and 28 adults) with acute diarrhea in 1998, 2000, and 2002. Samples were obtained during outpatient consultations (73%) and from hospitalized patients (27%). Although more than 20 different G-P combinations were identified, only 52% represented the globally most common types G1P[8], G2P[4], and G4P[8]. The G9 genotype, which is emerging worldwide, was identified in 12% of all samples. Twenty-one percent of the samples were of mixed genotypic origin, which is the highest frequency reported in any European population. The standard reverse transcription-PCR methods initially failed to identify a considerable fraction of the rotavirus P strains due to mutations at the VP4 primer-binding sites of P[8] strains. The application of a degenerate P[8] primer resulted in typing of most VP4 strains. There was considerable year-to-year variation among the circulating G-P types, and whereas G1P[8] was predominant in 1998 (42% of samples) and 2002 (26%), G2P[4] was the strain that was most frequently detected in 2000 (26% of samples). Our findings might implicate challenges for rotavirus vaccine implementation in a European population and underscore the importance of extensive strain surveillance prior to, during, and after introduction of any vaccine candidate.

Serum levels of soluble urokinase plasminogen activator receptor is associated with parasitemia in children with acute Plasmodium falciparum malaria infection.

Serum levels of soluble urokinase plasminogen activator receptor (suPAR) are significantly elevated and of prognostic value in patients suffering from serious infectious diseases such as HIV and tuberculosis. Our objective was to investigate suPAR levels during symptomatic malaria infection and 7 days after treatment. Children younger than 6 years who presented with fever or other symptoms compatible with malaria were enrolled. Blood films and samples were collected on day 0 and day 7. Twenty-five children were allocated to each of three groups according to the amount of Plasmodium falciparum detected in their initial blood film. Children in group 1 had parasite densities in excess of 20 parasites per 200 leucocytes. The median plasma suPAR level was 6.49 ng/mL (interquartile range [IQR]: 4.90-7.61) and correlated to parasitemia (Spearman 0.43, P < 0.0001). Blood was obtained from 20 children in group 1 after 7 days of treatment. All became malaria negative in their blood slides and all decreased in suPAR level to median 3.48 ng/mL (IQR: 3.08-3.91) (P < 0.0001). Group 2 consisted of 25 children with 1-20 parasites in their blood slide. The suPAR level was median 2.91 ng/mL (IQR: 2.27-4.40) and decreased with median 0.5 ng/mL following treatment (P = 0.0002). Group 3 showed to be negative in their blood slides and most received antibiotic treatment. suPAR decreased from median 3.26 ng/mL (IQR: 2.77-4.46) to median 2.47 ng/mL (IQR: 2.01-3.75), on day 7 (P = 0.006). This study demonstrates an important association between suPAR and acute malaria infection in humans.

Characterization of incompletely typed rotavirus strains from Guinea-Bissau: identification of G8 and G9 types and a high frequency of mixed infections.

Among 167 rotavirus specimens collected from young children in a suburban area of Bissau, Guinea-Bissau, from 1996 to 1998, most identifiable strains belonged to the uncommon P[6], G2 type and approximately 50% remained incompletely typed. In the present study, 76 such strains were further characterized. Due to interprimer interaction during the standard multiplex PCR approach, modifications of this procedure were implemented. The modified analyses revealed a high frequency of G2, G8, and G9 genotypes, often combined with P[4] and/or P[6]. The Guinean G8 and G9 strains were 97 and 98%, respectively, identical to other African G8 and G9 strains. Multiple G and/or P types were identified at a high frequency (59%), including two previously undescribed mixed infections, P[4]P[6], G2G8 and P[4]P[6], G2G9. These mixed infections most likely represent naturally occurring reassortance of rotavirus strains. Detection of such strains among the previously incompletely typed strains indicates a potential underestimation of mixed infections, if only a standard multiplex PCR procedure is followed. Furthermore cross-priming of the G3 primer with the G8 primer binding site and silent mutations at the P[4] and P[6] primer binding sites were detected. These findings highlight the need for regular evaluation of the multiplex primer PCR method and typing primers. The high frequency of uncommon as well as reassortant rotavirus strains in countries where rotavirus is an important cause of child mortality underscores the need for extensive strain surveillance as a basis to develop appropriate rotavirus vaccine candidates.