Australia’s active hospital-based surveillance for severe childhood disease

Our work

PAEDS is currently conducting surveillance on acute flaccid paralysis, acute childhood encephalitis, influenza, pertussis, varicella and herpes zoster, invasive group A streptococcus, invasive meningococcal disease, Kawasaki disease and Gram-negative blood stream infections. 

  • Acute flaccid paralysis
    Principal investigator 

    Dr Philip Britton

    Surveillance for acute flaccid paralysis (AFP) has been conducted by PAEDS since 2007. To retain Australia's polio-free status, it is important that Australia contributes to AFP surveillance, including meeting World Health Organization (WHO) surveillance targets related to case identification, stool collection and case investigation. This work contributes to the goal of global polio eradication.

    PAEDS centres continue to notify most of the AFP cases that are reported in Australia to the Polio Expert Panel of the Department of Health and provide stool samples to the Victorian Infectious Diseases Reference Laboratory (VIDRL) for testing for enteric pathogens. Together with the Australian Paediatric Surveillance Unit (APSU; http://www.apsu.org.au/) and National Enterovirus Reference Laboratory(NERL/VIDRL; http://www.vidrl.org.au/laboratories/poliovirus-reference/), PAEDS has helped achieve WHO benchmarks each year since 2007. A recent review of Polio surveillance in Australia confirmed the importance of PAEDS surveillance for AFP.

  • Acute childhood encephalitis
    Principal investigator 

    Dr Philip Britton

    Encephalitis is a complex neurological syndrome caused by inflammation of the brain. Children are among those most severely affected. However, there is limited knowledge about the causes of encephalitis in children worldwide and a cause is not found in up to 70% of cases using routine testing.

    Australia has unique viruses and other infectious agents that potentially cause encephalitis. There is also increasing awareness of immune-mediated causes of encephalitis, but these have not been systematically studied in children.

    The Australian Childhood Encephalitis study, led by Professor Cheryl Jones and Dr Philip Britton, aims to describe the causes, clinical features and consequences of this severe disease among Australian children.

    A 6-month pilot of surveillance for this complex condition began in 2013 at The Children's Hospital at Westmead site only, with roll-out to other states from early 2014. To date, this study has shown considerable success in better understanding acute encephalitis and its causes as well as demonstrating the effectiveness of syndromic surveillance using the PAEDS system in identifying outbreaks related to emerging infectious diseases in children.

  • Influenza
    Principal investigator 

    Associate Professor Christopher Blyth 

    Influenza is the most common vaccine preventable disease and a common cause of hospitalisation for children. PAEDS has been conducting surveillance for hospitalised influenza, in collaboration with the inFluenza Complications Alert Network (FluCAN), led by Professor Allen Cheng. Two sites (The Children’s Hospital at Westmead and Perth Children’s Hospital) joined FluCAN in 2014 and additional PAEDS sites joined the network in 2017, with the assistance of NHMRC partnership grant.

    This research has demonstrated the previously unrecognised burden of influenza in paediatric hospitals, explored risk factors for severe disease, evaluated antiviral and vaccine use and estimated vaccine effectiveness on an annual basis (Blyth et al, Eurosurveillance 2016; Blyth et al, Clinical Infectious Diseases 2019). Young children (<5 years), Aboriginal and Torres Strait Islander children and children with underlying medical conditions remain at significantly increased risk of hospitalised influenza. One in ten children admitted to hospital with influenza are admitted to the intensive care unit. Although most hospitalisations are short (less than 3 days), many children have prolonged hospitalisation. Although uncommon, influenza-associated deaths continue to occur.

    Despite significant variation between years, vaccination is the most effective prevention strategy we have. PAEDS-FluCAN has demonstrated vaccine effectiveness in young children and children with comorbidities. In addition, the effectiveness of vaccinating pregnant women to prevent infant disease has been demonstrated. Vaccine effectiveness estimates are provided to the national influenza committee to inform strain choice for future annual vaccines. PAEDS-FluCAN has led an advocacy campaign to highlight the need for vaccination in children. Vaccine coverage has increased significantly in recent years, in both children and pregnant women, with the Commonwealth and state governments now providing free influenza vaccination for all children 6 months to 5 years; all children 6 months and older with underlying medical conditions; all Aboriginal and Torres Strait Islander children from 6 months of age; and pregnant women.

  • Pertussis
    Principal investigator 

    Associate Professor Nick Wood

    Despite immunisation coverage approaching 93%, pertussis continues to cause significant morbidity and mortality, particularly in very young Australian children. The aims of this surveillance are to determine the burden of disease from hospitalised pertussis, with special emphasis on the duration of hospitalisation, use of intensive care, death and disability. Possible sources of infection and comorbidities to severity of pertussis are examined. The NHMRC-funded Partnership Project (APP1113851) seeks to estimate the effectiveness of pertussis vaccination (either in infancy or maternal) against pertussis hospitalisations and emergency department presentations by comparing pertussis vaccination status in infants with pertussis <6 months of age and test-negative controls. These surveillance data will assist in optimising pertussis prevention strategies.

  • Social research

    Each year, approximately 1,440 children aged <15 years are hospitalised due to influenza in Australia. Hospitalisation rates are the highest in infants, and deaths continue to occur. Despite influenza vaccination being strongly recommended and funded for all those aged 6 months – 5 years those with comorbidities and all Aboriginal and Torres Strait Islander children, uptake is considerably low, and thus there are significant gaps in the evidence base needed that guides policy and practice to better control influenza in Australia.

    We are undertaking a social research project, led by The University of Sydney PhD student, Samantha Carlson, which aims to understand the attitudes about and access to influenza vaccination experienced by parents of children hospitalised for influenza. Guided by the social ecological model (SEM) and Capability-Opportunity-Motivation-Behaviour (COM-B) model, we are examining the influence of social networks, community, the health system, policies and providers on parent’s behaviour regarding paediatric and antenatal influenza vaccination.

    In 2017, we conducted in-depth interviews with parents of children hospitalised for influenza to understand their disease and vaccination experience. The results from these interviews, in addition to other published studies, were used to develop a questionnaire. The questionnaire was piloted in 2018 with parents of children hospitalised for influenza, and lessons learned have been incorporated into a large nationwide case–control study which be recruiting participants from April–October 2019. Guided by the results of the project, recommendations and strategies will be developed that will aim to prevent children from acquiring influenza and other vaccine-preventable diseases. The importance, implementability and impact of these recommendations on immunisation policy and practice will be assessed by a group of immunisation experts, health care professionals and policy makers.

  • Varicella and herpes zoster
    Principal investigator 

    Associate Professor Helen Marshall 

    Varicella vaccine was included on the National Immunisation Program in 2005 for all children at age 18 months, with catch-up vaccination via school-based programs. PAEDS has been conducting surveillance for hospitalised varicella since 2007. Information is collected on complications of chickenpox (varicella-zoster virus infection) and children hospitalised with shingles (herpes zoster).

    An important and unique aspect of this surveillance is that genotyping of the virus is also undertaken. Given that varicella has not been nationally notifiable in Australia, this surveillance has made an important contribution toward demonstrating the impact of the varicella vaccination program on severe disease.

    In 2013, PAEDS published the first major study (Marshall et al, PIDJ 2013) to show a decline in hospitalised varicella and herpes zoster – estimated at 73% and 40%, respectively – since vaccine program commencement. In addition, all genotypes were ‘wild-type’ virus with no hospitalised cases due to any genotypes associated with the varicella vaccine. Of hospitalised children age-eligible for varicella vaccine, 80% were unimmunised, including all cases requiring intensive care. This reinforces the importance of vaccination.

    Surveillance for varicella is ongoing. Most recently we identified that while vaccination provided some protection against more severe disease, breakthrough varicella requiring hospitalisation still occurs in some children vaccinated with a one-dose schedule,  providing evidence to support consideration of a 2-dose varicella vaccination schedule. 

  • Invasive group A streptococcus disease
    Principal investigator 

    Associate Professor Nigel Crawford

    The group A streptococcus (GAS) bacteria is a common infective agent in children and adults that causes the widest range of clinical disease in humans of any bacterium. The spectrum of GAS disease can be divided into superficial, invasive, toxin mediated and post-infectious diseases. The most common infections caused by GAS are superficial, pharyngitis and pyoderma, which occur particularly in children. Invasive diseases are less common but have high rates of mortality and long-term morbidity. They include bacteraemia, including toxic shock syndrome, necrotising fasciitis and meningitis.

    Currently there is no vaccine to prevent invasive group A streptococcal infection. The streptococcal M protein that is used as the substrate for epidemiological typing is the major virulence factor of group A streptococcus and is a key vaccine target. There are over 220 variants of this protein described.

    Surveillance of invasive group A streptococcus (IGAS) disease began as a pilot at The Royal Children’s Hospital in Melbourne in 2015, and was rolled out nationally to all PAEDS sites in 2016.

  • Invasive meningococcal disease
    Principal investigator 

    Associate Professor Helen Marshall 

    Although meningococcal is an uncommon infection, the consequences of this disease can be death in 5-10% of cases and long-term disability in up to 40% of children. Until 2013, rates of meningococcal disease were decreasing, but since then rates have increased, with around 250 individuals affected annually, the majority of whom are children and adolescents. The increase has been due to a hypervirulent W strain in addition to the B strain and emergence of disease due to the Y strain.

    Surveillance through PAEDS began in 2016 and provides the opportunity to collect detailed clinical data in a timely manner to inform meningococcal immunisation strategies and measure vaccine effectiveness. As a national MenACWY program for infants has recently been introduced in Australia and for adolescents commencing in April 2019, PAEDS offers the opportunity to assist in monitoring the impact of these programs, particularly in relation to the impact on disease severity.

  • Kawasaki disease
    Principal investigator 

    Associate Professor Davinder Singh-Grewal

    Kawasaki disease is an enigmatic condition that can be difficult to diagnose. One of the difficulties is the lack of a diagnostic test - doctors diagnose the disease on the basis of clinical criteria (such as the presence of a rash, fever, swollen lymph nodes and red eyes). Unfortunately many other conditions can look just like Kawasaki disease, making it very difficult to decide which children need to be treated with intravenous immunoglobulin (IVIG). One of the long-term goals of this study is to help develop a diagnostic test so that children with Kawasaki disease can be diagnosed and treated earlier.

    Much of the funding for these studies has been kindly provided by the National Blood Authority. IVIG is a blood product that comes from blood donors. As such it is a highly valuable, and sometimes scarce, resource. It is hoped that this research will help to make more informed decisions about how IVIG is used in the management of Kawasaki disease. Recruitment commenced in January 2019.

  • Gram-negative blood stream infections
    Principal investigator 

    Dr Adam Irwin

    Bloodstream infections (BSI) in children are increasingly healthcare-associated and occur in those with complex comorbidities. In these children, Gram-negative organisms cause almost one half of all BSI and are associated with significant mortality. In an era when the threat of antimicrobial resistance is growing, Gram-negative BSI (GNBSI) represent a significant concern. The development and evaluation of new, effective antimicrobials for resistant Gram-negative infections is particularly limited in children.
    Existing surveillance systems rarely capture paediatric-specific data.

    We have established prospective surveillance of GNBSI in children in tertiary children’s hospitals throughout Australia. This surveillance is necessary to understand the clinical and molecular epidemiology of GNBSI and multi-drug resistant GNBSI in children. It will augment data collected by the Australian Group on Antimicrobial Resistance Gram-negative Sepsis Outcome Program, and will help to explain transmission dynamics of both susceptible and resistant invasive Gram-negative organisms in Australian children. Recruitment commenced in January 2019.

  • Intussusception
    Principal investigator 

    Associate Professor Jim Buttery

    Intussusception is the most common cause of bowel obstruction in infants and young children and was associated with a previous rotavirus vaccine in the USA which was withdrawn in 1999. Timely, active and systematic surveillance of intussusception cases is important and has identified a temporal but low incidence association with the rotavirus vaccines currently available under the National Immunisation Program (since July 2007). Surveillance also aims to describe the epidemiology, aetiology and severity of intussusception. Surveillance of intussusception is currently paused.

  • Febrile seizures
    Principal investigator 

    Associate Professor Nick Wood

    Febrile seizures are the most common type of childhood seizures, occurring 1 in 30 children aged 6 months to 6 years. They are associated with a sudden rise in temperature, most often from a viral illness. Certain vaccines, including measles-containing vaccines and some influenza vaccines, have been associated with an increased risk of febrile seizures. A PAEDS study was conducted between May 2013 and June 2014, gathering detailed clinical and epidemiological information on all febrile seizure presentations to 5 PAEDS sites. These data were used to determine the risk of febrile seizures following the introduction of new vaccines on the National Immunisation Program and to compare clinical outcomes of children who experienced a febrile seizure following a vaccination with children who experienced a febrile seizure unrelated to a vaccination event. The results of these studies have been published. In addition, children in this study were invited to participate in an NHMRC-funded longer-term follow-up study, led by Associate Professor Nicholas Wood, examining these children’s developmental outcomes and genetic susceptibility to febrile seizures compared with healthy children.