Search

The incidence of respiratory syncytial virus (RSV) in adults is inadequately defined and the impact of SARS-CoV-2-related non-pharmaceutical interventions (NPIs) is underexplored. Using laboratory data, we described the detection rate of RSV in adults ≥16 years in Western Australia (WA) between 2017 and 2023. With the exception of 2020, RSV detections rose annually between 2017 and 2023, reaching 50.7 per 100,000 in 2023 (95% confidence interval [CI], 47.9–53.8). RSV testing expanded considerably across the study period, with the testing in 2023 more than five times the 2017 total. The detection rate was highest in adults ≥60 years between 2017 and 2019, particularly those ≥75 years. Following 2020, the detections in all age groups increased, with the highest detection rate in 2023 in those ≥75-years (199.5 per 100,000; 95% CI, 180.5–220). NPIs significantly impacted RSV seasonality; the preceding winter pattern was disrupted, resulting in an absent 2020 winter season and two major summer seasons in 2020/21 and 2021/22. The RSV season began to realign in 2022, reverting to a winter seasonal pattern in 2023 and the largest season in the study period. Ongoing surveillance will be required to understand the stability of these increases and to delineate the impact of new immunisation strategies. [ABSTRACT FROM AUTHOR]

Mosquitoes harbor a wide diversity of microorganisms, including viruses that are human pathogens, or that are insect specific. We used metatranscriptomics, an unbiased high-throughput molecular approach, to describe the composition of viral and other microbial communities in six medically important mosquito species from across Western Australia: Aedes vigilax, Culex annulirostris, Cx. australicus, Cx. globocoxitus, Cx. pipiens biotype molestus, and Cx. quinquefasciatus. We identified 42 viral species, including 13 novel viruses, from 19 families. Culex mosquitoes exhibited a significantly higher diversity of viruses than Aedes mosquitoes, and no virus was shared between the two genera. Comparison of mosquito populations revealed a heterogenous distribution of viruses between geographical regions and between closely related species, suggesting that geography and host species may play a role in shaping virome composition. We also detected bacterial and parasitic microorganisms, among which Wolbachia bacteria were detected in three members of the Cx. pipiens complex, Cx. australicus, Cx. pipiens biotype molestus, and Cx. quinquefasciatus. In summary, our unbiased metatranscriptomics approach provides important insights into viral and other microbial diversity in Western Australian mosquitoes that vector medically important viruses. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) reinfection in children is poorly understood. We examined the incidence, characteristics, and outcomes of hospital-attended RSV reinfections in children <16 years in Western Australia between 2012 and 2022. Individuals with repeat RSV detections ≥56 days apart were identified using laboratory data. The incidence of reinfection in the first five years of life was estimated using the total birth population from 2012 to 2017. Clinical data on a subset of reinfection episodes were obtained from two metropolitan pediatric centers. A total of 466 children with hospital-attended reinfections were identified. The median interval between RSV detections was 460 days (interquartile range: 324, 812), with a reinfection rate of 95 per 100,000 individuals (95% confidence interval: 82, 109). Reinfection was most common in children who experienced their first RSV detection <6 months of age. Predisposing factors were identified in 56% of children; children with predisposing factors were older at first and second detections, were more likely to be admitted, and had a longer length of stay. This study highlights the significant burden of hospital-attended RSV reinfections in children with and without predisposing factors. Expanded surveillance with in-depth clinical data is required to further characterize the impact of RSV reinfection. [ABSTRACT FROM AUTHOR]

Background The association between early-life respiratory syncytial virus (RSV) infections and later respiratory morbidity is well established. However, there is limited evidence on factors that influence this risk. We examined sociodemographic and perinatal factors associated with later childhood respiratory morbidity requiring secondary care following exposure to a laboratory-confirmed RSV episode in the first 2 years. Methods We used a probabilistically linked whole-of-population-based birth cohort including 252 287 children born in Western Australia between 2000 and 2009 with follow-up to the end of 2012. Cox proportional hazards models estimated adjusted hazard ratios (aHRs) of the association of various risk factors with the first respiratory episode for asthma, wheezing, and unspecified acute lower respiratory infection beyond the age of 2 years. Results The analytic cohort included 4151 children with a confirmed RSV test before age 2 years. The incidence of subsequent respiratory morbidity following early-life RSV infection decreased with child age at outcome (highest incidence in 2–<4-year-olds: 41.8 per 1000 child-years; 95% CI, 37.5–46.6), increased with age at RSV infection (6–<12-month-olds: 23.6/1000 child-years; 95% CI, 19.9–27.8; 12–<24-month-olds: 22.4/1000 child-years; 95% CI, 18.2–22.7) and decreasing gestational age (50.8/1000 child-years; 95% CI, 33.5–77.2 for children born extremely preterm, <28 weeks gestation). Risk factors included age at first RSV episode (6–<12 months: aHR, 1.42; 95% CI, 1.06–1.90), extreme prematurity (<28 weeks: aHR, 2.22; 95% CI, 1.40–3.53), maternal history of asthma (aHR, 1.33; 95% CI, 1.04–1.70), and low socioeconomic index (aHR, 1.76; 95% CI, 1.03–3.00). Conclusions Our results suggest that in addition to preterm and young infants, children aged 12–<24 months could also be potential target groups for RSV prevention to reduce the burden of later respiratory morbidities associated with RSV. [ABSTRACT FROM AUTHOR]

Aim: Western Australian laboratory data demonstrated a decrease in human metapneumovirus (hMPV) detections through 2020 associated with SARS‐CoV‐2‐related non‐pharmaceutical interventions (NPIs), followed by a subsequent surge in metropolitan region in mid‐2021. We aimed to assess the impact of the surge in hMPV on paediatric hospital admissions and the contribution of changes in testing. Methods: All respiratory‐coded admissions of children aged <16 years at a tertiary paediatric centre between 2017 and 2021 were matched with respiratory virus testing data. Patients were grouped by age at presentation and by ICD‐10 AM codes into bronchiolitis, other acute lower respiratory infection (OALRI), wheeze and upper respiratory tract infection (URTI). For analysis, 2017–2019 was utilised as a baseline period. Results: hMPV‐positive admissions in 2021 were more than 2.8 times baseline. The largest increase in incidence was observed in the 1–4 years group (incidence rate ratio (IRR) 3.8; 95% confidence interval (CI): 2.5–5.9) and in OALRI clinical phenotype (IRR 2.8; 95% CI: 1.8–4.2). The proportion of respiratory‐coded admissions tested for hMPV in 2021 doubled (32–66.2%, P < 0.001), with the greatest increase in wheeze (12–75% in 2021, P < 0.001). hMPV test percentage positivity in 2021 was higher than in the baseline period (7.6% vs. 10.1% in 2021, P = 0.004). Conclusion: The absence and subsequent surge underline the susceptibility of hMPV to NPIs. Increased hMPV‐positive admissions in 2021 can be partially attributable to testing, but test‐positivity remained high, consistent with a genuine increase. Continued comprehensive testing will help ascertain true burden of hMPV respiratory diseases. [ABSTRACT FROM AUTHOR]

Background: Respiratory syncytial virus (RSV) seasonality is dependent on the local climate. We assessed the stability of RSV seasonality prior to the SARS‐CoV‐2 pandemic in Western Australia (WA), a state spanning temperate and tropical regions. Method: RSV laboratory testing data were collected from January 2012 to December 2019. WA was divided into three regions determined by population density and climate: Metropolitan, Northern and Southern. Season threshold was calculated per region at 1.2% annual cases, with onset the first of ≥2 weeks above this threshold and offset as the last week before ≥2 weeks below. Results: The detection rate of RSV in WA was 6.3/10,000. The Northern region had the highest detection rate (15/10,000), more than 2.5 times the Metropolitan region (detection rate ratio 2.7; 95% CI, 2.6–2.9). Test percentage positive was similar in the Metropolitan (8.6%) and Southern (8.7%) regions, with the lowest in the Northern region (8.1%). RSV seasons in the Metropolitan and Southern regions occurred annually, with a single peak and had consistent timing and intensity. The Northern tropical region did not experience a distinct season. Proportion of RSV A to RSV B in the Northern region differed from the Metropolitan region in 5 of the 8 years studied. Conclusions: Detection rate of RSV in WA is high, especially in the Northern region, where climate, an expanded at‐risk population and increased testing may have contributed to greater numbers. Before the SARS‐CoV‐2 pandemic, RSV seasonality in WA was consistent in timing and intensity for the Metropolitan and Southern regions. [ABSTRACT FROM AUTHOR]

Non-pharmaceutical interventions (NPIs) to reduce SARS-CoV-2 transmission disrupted respiratory virus seasonality. We examined the unusual return of human metapneumovirus (hMPV) in Western Australia following a period of absence in 2020. We analysed hMPV laboratory testing data from 1 January 2017 to 31 December 2021. Whole-genome sequencing of selected hMPV-positive samples was performed using a tiled-amplicon approach. Following an absence in spring 2020, an unusual hMPV surge was observed during the wet summer season in the tropical Northern region in late 2020. Following a six-month delay, an intense winter season occurred in the subtropical/temperate Southern and Metropolitan regions. Compared to 2017–2019, hMPV incidence in 2021 increased by 3-fold, with a greater than 4-fold increase in children aged 1–4 years. There was a collapse in hMPV diversity in 2020, with the emergence of a single subtype. NPIs contributed to an absent 2020 season and a clonal hMPV resurgence. The summer surge and delayed winter season suggest that prevailing temperature and humidity are keys determinant of hMPV transmission. The increased incidence in 2021 was linked to an expanded cohort of hMPV-naïve 1–4-year-old children and waning population immunity. Further intense and unusual respiratory virus seasons are expected as COVID-19 associated NPIs are removed. [ABSTRACT FROM AUTHOR]

Background: Following a relative absence in winter 2020, a large resurgence of respiratory syncytial virus (RSV) detections occurred during the 2020/2021 summer in Western Australia. This seasonal shift was linked to SARS-CoV-2 public health measures. We examine the epidemiology and RSV testing of respiratory-coded admissions, and compare clinical phenotype of RSV-positive admissions between 2019 and 2020.Method: At a single tertiary paediatric centre, International Classification of Diseases, 10th edition Australian Modification-coded respiratory admissions longer than 12 hours were combined with laboratory data from 1 January 2019 to 31 December 2020. Data were grouped into bronchiolitis, other acute lower respiratory infection (OALRI) and wheeze, to assess RSV testing practices. For RSV-positive admissions, demographics and clinical features were compared between 2019 and 2020.Results: RSV-positive admissions peaked in early summer 2020, following an absent winter season. Testing was higher in 2020: bronchiolitis, 94.8% vs 89.2% (p=0.01); OALRI, 88.6% vs 82.6% (p=0.02); and wheeze, 62.8% vs 25.5% (p<0.001). The 2020 peak month, December, contributed almost 75% of RSV-positive admissions, 2.5 times the 2019 peak. The median age in 2020 was twice that observed in 2019 (16.4 vs 8.1 months, p<0.001). The proportion of RSV-positive OALRI admissions was greater in 2020 (32.6% vs 24.9%, p=0.01). There were no clinically meaningful differences in length of stay or disease severity.Interpretation: The 2020 RSV season was in summer, with a larger than expected peak. There was an increase in RSV-positive non-bronchiolitis admissions, consistent with infection in older RSV-naïve children. This resurgence raises concern for regions experiencing longer and more stringent SARS-CoV-2 public health measures. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) is an important human respiratory pathogen. In temperate regions, a distinct seasonality is observed, where peaks of infections typically occur in early winter, often preceding the annual influenza season. Infections are associated with high rates of morbidity and mortality and in some populations exceed that of influenza. Two subtypes, RSV-A and RSV-B, have been described, and molecular epidemiological studies have shown that both viruses mostly co-circulate. This trend also appears to be the case for Australia; however, previous genomic studies have been limited to cases from one Eastern state—New South Wales. As such, the broader spatial patterns and viral traffic networks across the continent are not known. Here, we conducted a whole-genome study of RSV comparing strains across eastern and Western Australia during the period January 2016 to June 2017. In total, 96 new RSV genomes were sequenced, compiled with previously generated data, and examined using a phylodynamic approach. This analysis revealed that both RSV-A and RSV-B strains were circulating, and each subtype was dominated by a single genotype, RSV-A ON1-like and RSV-B BA10-like viruses. Some geographical clustering was evident in strains from both states with multiple distinct sub-lineages observed and relatively low mixing across jurisdictions, suggesting that endemic transmission was likely seeded from imported, unsampled locations. Overall, the RSV phylogenies reflected a complex pattern of interactions across multiple epidemiological scales from fluid virus traffic across global and regional networks to fine-scale local transmission events. [ABSTRACT FROM AUTHOR]

Public health measures targeting coronavirus disease 2019 have potential to impact transmission of other respiratory viruses. We found 98.0% and 99.4% reductions in respiratory syncytial virus and influenza detections, respectively, in Western Australian children through winter 2020 despite schools reopening. Border closures have likely been important in limiting external introductions. [ABSTRACT FROM AUTHOR]

Background: Infectious disease burden is commonly assessed using notification data. Using retrospective record linkage in Western Australia, we described how well notification data captures laboratory detections of influenza, pertussis and invasive pneumococcal disease (IPD).Methods: We linked data from the Western Australian Notifiable Infectious Diseases Database (WANIDD) and the PathWest Laboratory Database (PathWest) pertaining to the Triple I birth cohort, born in Western Australia in 1996-2012. These were combined to calculate the number of unique cases captured in each dataset alone or in both datasets. To assess the impact of under-ascertainment, we compared incidence rates calculated using WANIDD data alone and using combined data.Results: Overall, there were 5550 influenza, 513 IPD (2001-2012) and 4434 pertussis cases (2000-2012). Approximately 2% of pertussis and IPD cases and 7% of influenza cases were solely recorded in PathWest. Notification of influenza and pertussis cases to WANIDD improved over time. Overall incidence rates of influenza in children aged <5 years using both datasets was 10% higher than using WANIDD data alone (IRR = 1.1, 95% CI = 1.1-1.2).Conclusions: This is the first time WANIDD data have been validated against routinely collected laboratory data. We anticipated all cases would be captured in WANIDD but found additional laboratory-confirmed cases that were not notified. Studies investigating pathogen-specific infectious disease would benefit from using multiple data sources. [ABSTRACT FROM AUTHOR]

During 2010–2012 the strain composition of the influenza vaccine in the Southern Hemisphere did not change, but the circulating virus type/subtype did. We pooled data for these years from the Western Australian sentinel medical practice surveillance system for influenza to estimate vaccine effectiveness (VE) by influenza virus type and subtype. A case test-negative design was used with VE estimated as (1-odds ratio) × 100%. There were 2182 patients included in the analysis across the 3 years studied. The predominant subtype was A/H1pdm09 in 2010 and 2011, and A/H3 in 2012. The overall adjusted VE estimate against all influenza for 2010–2012 was 51% (95% CI: 36, 63). Estimates were highest against A/H1pdm09 at 74% (95% CI: 47, 87), followed by 56% (95% CI: 33, 71) for influenza B and lowest against A/H3 at 39% (95% CI: 13, 57). When analyses were restricted to compare influenza-positive patients with patients who tested positive for a non-influenza virus, overall adjusted VE was 59% (95% CI: 39, 72). These results suggest moderate protection against influenza by vaccination in Western Australia over the period 2010–2012, and are consistent with findings from other settings. [ABSTRACT FROM AUTHOR]

Metagenomics revealed an impressive breadth of previously unrecognized viruses. Here, we report the virome of the Culex annulirostris Skuse mosquito, an important vector of pathogenic arboviruses in Australia. Mosquitoes were collected from three sites in the Kimberley region of Western Australia. Unbiased high-throughput sequencing (HTS) revealed the presence of 16 novel viral sequences that share less than 90% identity with known viruses. None were closely related to pathogenic arboviruses. Viruses were distributed unevenly across sites, indicating a heterogeneous Cx. annulirostris virome. Polymerase chain reaction assays confirmed HTS data and identified marked variation between the virus prevalence identified at each site. [ABSTRACT FROM AUTHOR]

The discovery of hepaciviruses in non-human hosts has accelerated following the advancement of high-throughput sequencing technology. Hepaciviruses have now been described in reptiles, fish, birds, and an extensive array of mammals. Using metagenomic sequencing on pooled samples of field-collected Culex annulirostris mosquitoes, we discovered a divergent hepacivirus-like sequence, named Jogalong virus, from the Kimberley region in northern Western Australia. Using PCR, we screened the same 300 individual mosquitoes and found just a single positive sample (1/300, 0.33%). Phylogenetic analysis of the hepacivirus NS5B protein places Jogalong virus within the genus Hepacivirus but on a distinct and deeply rooted monophyletic branch shared with duck hepacivirus, suggesting a notably different evolutionary history. Vertebrate barcoding PCR targeting two mitochondrial genes, cytochrome c oxidase subunit I and cytochrome b, indicated that the Jogalong virus-positive mosquito had recently fed on the tawny frogmouth (Podargus strigoides), although it is currently unknown whether this bird species contributes to the natural ecology of this virus. [ABSTRACT FROM AUTHOR]

Background: In 2007-08, a genotype J mumps outbreak occurred among Aboriginal people in northern Western Australia, despite high vaccine coverage. In March, 2015, a second protracted mumps outbreak occurred in northern Western Australia and spread widely across rural areas of the state. This time the outbreak was caused by a genotype G virus and again primarily affected Aboriginal people. We aimed to describe the epidemiology of this outbreak.Methods: In this population-based surveillance study, we analysed statutory notifications and public health case follow-up data from the Western Australia Notifiable Infectious Diseases Database and vaccination information from the Australian Childhood Immunisation Register. An outbreak case of mumps was notified if the affected person was living in or visiting a community in Western Australia where there was active mumps transmission, and if mumps infection was confirmed by laboratory diagnosis or by an epidemiological link. We analysed case demographics, vaccination status, and age-standardised attack rates in Aboriginal and non-Aboriginal people by region of notification. Laboratory diagnoses were made by real-time RT-PCR, serology, or both, and carried out by the sole public pathology provider in Western Australia.Findings: Between March 1, 2015, and December 31, 2016, 893 outbreak cases were notified. 798 (89%) of 893 outbreak cases were reported in Aboriginal people. 40 (4%) of 893 people were admitted to hospital, and 33 (7%) of 462 men reported orchitis. Mumps attack rates increased sharply with age, peaking in the 15-19 age group. 371 (89%) of 419 people aged 1-19 years were fully vaccinated and 29 (7%) were partly vaccinated. Of the 240 people who tested positive by real-time RT-PCR and had also been tested for mumps-specific IgG and IgM, 165 (69%) were positive for IgG but negative for IgM, indicating the importance of RT-PCR testing for diagnosis in vaccinated populations. None of the cases from the 2007-08 genotype J outbreak were re-notified.Interpretation: The number of mumps outbreaks reported in recent years among highly vaccinated populations, including Indigenous populations, has been growing. More widespread and pre-emptive use of the third dose of measles, mumps, and rubella vaccine might be required to control and prevent future outbreaks in high-risk populations. Research should explore the benefit of increasing the intervals between vaccine doses to strengthen the durability of vaccine protection.Funding: None. [ABSTRACT FROM AUTHOR]

• Birth month in respect of RSV season plays an important role in the incidence of RSV-hospitalization. • Infants born preterm have a disproportional burden of severe RSV. • Timing and duration of a monoclonal antibody program is sensitive to a country's RSV season. Respiratory syncytial virus contributes to significant global infant morbidity and mortality. We applied a previously developed statistical prediction model incorporating pre-pandemic RSV testing data and hospital admission data to estimate infant RSV-hospitalizations by birth month and prematurity, focused on infants aged <1 year. The overall predicted RSV-hospitalization incidence rates in infants <6 months were 32.7/1,000 child-years (95 % CI: 31.8, 33.5) and 3.1/1,000 child-years (95 % CI: 3.0, 3.1) in infants aged 6-<12 months. Predicted RSV-hospitalization rates for infants aged <6 months were highest for infants born in April/May. Predicted rates for preterm infants born 29–32 weeks gestation were highest in March-May, whereas infants born >33 weeks had peak RSV-hospitalization rates from May-June, similar to late preterm or term births. RSV-hospitalization rates in the pre-pandemic era were highly seasonal, and seasonality varied with degree of prematurity. Accurate estimates of RSV-hospitalization in high-risk sub-groups are essential to understand preventable burden of RSV especially given the current prevention landscape. [ABSTRACT FROM AUTHOR]

Introduction: Acute lower respiratory infections (ALRIs) are a major contributor to the global infectious disease burden and a common cause of hospitalisation for children under 2 years. We compared clinical severity in children hospitalised with respiratory syncytial virus (RSV), parainfluenza virus (PIV), human metapneumovirus (hMPV) and influenza virus (IFV)., Methods: We used a probabilistically linked population cohort born in Western Australia between 2010 and 2020 and hospitalised before the age of 2 years. Outcomes compared included length of hospital stay (LOS), admission to intensive care unit (ICU), need for respiratory support (RS), complex hospital course (RS, death, ICU admission or LOS >75th percentile), 7-day and 30-day mortality, hospital-in-the-home care, 30-day all-cause and ALRI-specific readmissions and emergency department presentations 14 days prior to hospitalisation. Logistic regression was used for binary outcomes, and negative binomial regression was used for discrete count variables. Incidence rates, time to RS and time to readmissions were calculated using survival analysis techniques., Results: The final cohort included 210 997 hospitalised children under 24 months of age for a total of 315 769 admissions. Infants hospitalised before 6 months had the highest rates for all virus-specific hospitalisations, particularly RSV hospitalisations (50.4 per 1000 child-years (95% CI 48.7 to 52.1)). Infants <6 months had higher odds of an ICU admission (adjusted OR (aOR) 2.39, 95% CI 1.36 to 4.19) and RS (aOR 4.68, 95% CI 2.95 to 7.44) and a complex hospital course (aOR 2.69, 95% CI 2.13 to 3.42) with RSV and four times higher hazards of requiring RS earlier (adjusted HR (aHR) 4.06, 95% CI 2.59 to 6.36). An ALRI-coded 30-day readmission was recorded in 10%-24% of virus-specific hospitalisations., Discussion: Young infants have a more severe and complex hospital course with RSV hospitalisation compared with hospitalisation with other respiratory viruses and should be prioritised for prevention measures such as the single-dose monoclonal antibody, nirsevimab., Competing Interests: Competing interests: HCM has received institutional honoraria for participation in advisory committees sponsored by Merck Sharpe & Dohme (Australia) Pty, Pfizer and Sanofi for other work unrelated to this analysis. HCM also receives funding from Sanofi in the form of an externally sponsored collaboration agreement for other work unrelated to this analysis. PR has received institutional honoraria from advisory committees sponsored by GSK, Pfizer, Merck, AstraZeneca and Novavax. PR also receives funding from Merck Sharpe & Dohme (Australia) Pty and GSK. HCM and MS have received travel funding from Seqirus (unrelated to the work presented here). All other authors have no conflicts to declare., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: An understanding of viral testing rates is crucial to accurately estimate the pathogen-specific hospitalisation burden. We aimed to estimate the patterns of testing for respiratory syncytial virus (RSV), influenza virus, parainfluenza virus (PIV) and human metapneumovirus (hMPV) by geographical location, age and time in children <5 years old in Western Australia., Methods: We conducted a population-based cohort study of children born between 1 January 2010 and 31 December 2021, utilising linked administrative data incorporating birth and death records, hospitalisations and respiratory viral surveillance testing records from state-wide public pathology data. We examined within-hospital testing rates using survival analysis techniques and identified independent predictors of testing using binary logistic regression., Results: Our dataset included 46,553 laboratory tests for RSV, influenza, PIV, or hMPV from 355,021 children (52.5% male). Testing rates declined in the metropolitan region over the study period (RSV testing in infants: from 242.11/1000 child-years in 2012 to 155.47/1000 child-years in 2018) and increased thereafter. Conversely, rates increased in non-metropolitan areas (e.g., RSV in Goldfields: from 364.92 in 2012 to 504.37/1000 child-years in 2021). The strongest predictors of testing were age <12 months (adjusted odds ratio [aOR] = 2.25, 95% CI 2.20-2.31), preterm birth (<32 weeks: aOR = 2.90, 95% CI 2.76-3.05) and remote residence (aOR = 0.77, 95% CI 0.73-0.81)., Conclusion: These current testing rates highlight the potential underestimation of respiratory virus hospitalisations by routine surveillance and the need for estimation of the true burden of respiratory virus admissions., (© 2024 The Author(s). Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Background: Data demonstrating the effectiveness of inactivated trivalent influenza vaccine (TIV) for children at increased risk of severe disease are limited. Our objective was to determine the effectiveness of TIV in children with risk factors for severe disease and to compare vaccine uptake, parental attitudes and prescriber recommendations in children with and without risk factors for severe disease., Methods: Children aged 6-59 months presenting for emergency care (2008 to 2014) with an influenza-like illness were eligible. Influenza polymerase chain reaction/culture was performed on nasopharyngeal samples. Vaccination status was confirmed via the national register and/or vaccine providers. The test-negative design was used to estimate vaccine effectiveness (VE). Risk factors, parental attitudes and prescriber recommendations were assessed by parental questionnaire., Results: Two thousand seven hundred twenty-three children were recruited. Risk factors for severe disease included comorbid medical conditions (11.6%), preterm birth (13.0%) and indigeneity (5.0%). Influenza was identified in 546 (20.1%) participants. Overall VE (2008 and 2010 to 2014) was 70.0% (95% confidence interval: 47.7 to 82.9); VE for children with medical comorbidities, children born preterm and children <2 years were 82.5% (14.6 to 96.4), 79.2% (10.9 to 95.1) and 84.7% (49.6 to 95.3), respectively. After adverse events in 2010, the number of children fully vaccinated with TIV declined significantly. This included children with and without risk factors for severe disease. Attitudes were similar in parents of children with and without risk factors for severe disease., Conclusions: VE for TIV in young children with and without risk factors for severe disease was ≥70%. Despite this, participation in the preschool influenza vaccination program remains low with parents and prescribers unconvinced of the benefits and safety of TIV.

Background: Intussusception, a condition where one segment of intestine invaginates into another, occurs predominantly in infants and young children. A number of potential causes have been identified including infectious agents and rotavirus vaccination. Following the introduction of rotavirus vaccination of infants in Western Australia, a laboratory surveillance programme testing notified intussusception cases for infectious agents was commenced. This led to a PCR-based study of the association between gastrointestinal viruses and intussusception., Objectives: Conduct viral testing on stool samples from intussusception patients to determine viruses that may have an association with intussusception., Study Design: A retrospective case-control study was conducted using stool samples collected from children with intussusception (n=74) and matched controls (n=289) between 2008 and 2011. Samples were tested for rotavirus, norovirus, adenovirus, enterovirus, rhinovirus, astrovirus, parechovirus and bocavirus. Adenovirus, enterovirus and rhinovirus species were determined by DNA sequencing., Results: Human adenovirus C was detected in significantly more cases than controls with 31/74 (41.9%) cases testing positive compared to 39/289 (13.49%) controls (OR=4.38, p<0.001). A significant difference was seen in Enterovirus B detections with 11/74 (14.9%) cases testing positive compared to 21/289 (7.3%) controls (OR=2.24, p=0.04). Rotavirus was detected in 7/74 (9.46%) cases and 11/289 (3.81%) controls, which was also a significant difference (OR=2.88, p=0.045)., Conclusions: Our results show that intussusception is associated with non-enteric adenovirus infections, and Enterovirus B infections. While a statistical association was seen with rotavirus and intussusception, we were not able to determine if this was related to vaccine strain or wild type rotavirus., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: There are few studies evaluating the effectiveness of trivalent influenza vaccination (TIV) in young children, particularly in children <2 years. The Western Australian Influenza Vaccine Effectiveness Study commenced in 2008 to evaluate a program providing TIV to children aged 6 to 59 months., Methods: An observational study enrolling children with influenza-like illness presenting to a tertiary pediatric hospital was conducted (2008-2012). Vaccination status was determined by parental questionnaire and confirmed via the national immunization register and/or vaccine providers. Respiratory virus polymerase chain reaction and culture were performed on nasopharyngeal samples. The test-negative design was used to estimate vaccine effectiveness (VE) by using 2 control groups: all influenza test-negative subjects and other-virus-detected (OVD) subjects. Adjusted odds ratios were estimated from models with season, month of disease onset, age, gender, indigenous status, prematurity, and comorbidities as covariates. Subjects enrolled in 2009 were excluded from VE calculations., Results: Of 2001 children enrolled, influenza was identified in 389 (20.4%) children. Another respiratory virus was identified in 1134 (59.6%) children. Overall, 295 of 1903 (15.5%) children were fully vaccinated and 161 of 1903 (8.4%) children were partially vaccinated. Vaccine uptake was significantly lower in 2010-2012 after increased febrile adverse events observed in 2010. Using test-negative controls, VE was 64.7% (95% confidence interval [CI]: 33.7%-81.2%). No difference in VE was observed with OVD controls (65.8%; 95% CI: 32.1%-82.8%). The VE for children <2 years was 85.8% (95% CI: 37.9%-96.7%)., Conclusions: This study reveals the effectiveness of TIV in young children over 4 seasons by using test-negative and OVD controls. TIV was effective in children aged <2 years. Despite demonstrated vaccine effectiveness, uptake of TIV remains suboptimal., (Copyright © 2014 by the American Academy of Pediatrics.)

Melioidosis became a notifiable disease in Western Australia (WA) 2 years after the West Kimberley melioidosis outbreak. Two cases of melioidosis caused by the outbreak genotype of Burkholderia pseudomallei (National Collection of Type Cultures [NCTC] 13177) occurred in 1998 and 1999 in persons who visited the outbreak location at the time. No other infections caused by the outbreak strain have been recorded in WA since that time, despite an average of four culture-positive cases per year. Sporadic cases of melioidosis often follow tropical storms and cyclones during summer, and they have been detected outside the endemic area when cyclones travel far inland. In 2007, environmental isolates resembling NCTC 13177 were found 500 km east of the outbreak location after unusually severe weather. Recent whole-genome analysis places NCTC 13177 genetically close to other Australian isolates. Additional biogeographic and ecological studies are needed to establish the relative importance of environmental cofactors in disease pathogenesis.

An investigation into the risk of occupationally acquired melioidosis at a mine site in northern Australia found that 45 (13%) of 345 staff had serologic evidence of exposure and 14 (4%) had recent exposure to Burkholderia pseudomallei or closely related bacteria. There was only one culture-confirmed case of melioidosis in mine staff during the study period. The lack of overt infection directly attributable to work activities despite detectable B. pseudomallei on site, the absence of an association between positive serology and occupational activity on site, or duration of employment in the mining industry stand against a significant occupationally acquired infection risk on this industrial site. Workplace exposure to a dust-generating tropical environment in the melioidosis-endemic north of Australia did not appear to pose a measurable increase in infection risk. The effect of long-term climatic trends on this potential biologic threat requires further study.