Testing the intrinsic mechanisms driving the dynamics of Ross River Virus across Australia.

The mechanisms driving dynamics of many epidemiologically important mosquito-borne pathogens are complex, involving combinations of vector and host factors (e.g., species composition and life-history traits), and factors associated with transmission and reporting. Understanding which intrinsic mechanisms contribute most to observed disease dynamics is important, yet often poorly understood. Ross River virus (RRV) is Australia's most important mosquito-borne disease, with variable transmission dynamics across geographic regions. We used deterministic ordinary differential equation models to test mechanisms driving RRV dynamics across major epidemic centers in Brisbane, Darwin, Mandurah, Mildura, Gippsland, Renmark, Murray Bridge, and Coorong. We considered models with up to two vector species (Aedes vigilax, Culex annulirostris, Aedes camptorhynchus, Culex globocoxitus), two reservoir hosts (macropods, possums), seasonal transmission effects, and transmission parameters. We fit models against long-term RRV surveillance data (1991-2017) and used Akaike Information Criterion to select important mechanisms. The combination of two vector species, two reservoir hosts, and seasonal transmission effects explained RRV dynamics best across sites. Estimated vector-human transmission rate (average ß = 8.04x10-4per vector per day) was similar despite different dynamics. Models estimate 43% underreporting of RRV infections. Findings enhance understanding of RRV transmission mechanisms, provide disease parameter estimates which can be used to guide future research into public health improvements and offer a basis to evaluate mitigation practices.

Estimating Australian Hospitalization Ratios and Costs for Wildtype SARS-CoV-2 in 2020.

Utilizing a retrospective cohort study of SARS-CoV-2 wildtype (Wuhan) strain, we aimed to 1) utilize the unique Australian experience of temporarily eliminating SARS-CoV-2 to document and estimate the hospitalization demand; and 2) estimate the inpatient hospital costs associated with treatment. Case data was based on Victoria Australia from March 29 to December 31, 2020. Outcomes measures included hospitalization demand and case fatality ratio and inpatient hospitalization costs. Population adjusted results indicated that 10.2% (CI 9.9%-10.5%) required ward only admission, 1.0% (CI 0.9%-1.1%) required ICU admission plus 1.0% (CI 0.9%-1.1%) required ICU with mechanical ventilation. The overall case fatality ratio was 2.9% (CI 2.7%-3.1%). Mean ward only patient costs ranged from $22,714 to $57,100 per admission whilst ICU patient costs ranged from $37,228 to $140,455. With delayed, manageable outbreaks and public health measures leading to temporary elimination of community transmission, the Victorian COVID-19 data provides insight into initial pandemic severity and hospital costs.

Hepatitis B prevalence in women giving birth in the Northern Territory, Australia, 2005-2015.

Background: Hepatitis B virus (HBV) vaccination in the Northern Territory (NT) was funded for all Aboriginal and Torres Strait Islander newborns in 1988 and for all newborns in 1990. The prevalence of HBV in the Northern Territory was found to be higher in Aboriginal and Torres Strait Islander women than in non-Indigenous women across 2005-2010. We examined more recent data to assess whether the gap remains. Methods: We linked data from two routinely collected registries, the NT Perinatal Register and the NT Notifiable Diseases System, to investigate the prevalence of HBV infection, according to eligibility for infant HBV vaccination, in women giving birth during 2005-2015. Results: There were 22,781 women recorded as giving birth in public hospitals in the Northern Territory during 2005-2015. Hepatitis B virus prevalence was highest in Aboriginal and Torres Strait Islander (1.8%) and overseas-born women (1.8%). Among Aboriginal and Torres Strait Islander women, estimated hepatitis B virus prevalence was significantly higher in those born before the implementation of the vaccination program than in those born afterwards (2.4% versus 0.3%). Prevalence was highest amongst those living in very remote areas, both overall (2.2%) and within the birth cohort eligible for HBV vaccination. Conclusions: Hepatitis B virus prevalence in Northern Territory Aboriginal and Torres Strait Islander women appears to be declining as more individuals vaccinated as part of infant vaccination programs reach adulthood. Prevalence remains highest in remote areas, highlighting the importance of ongoing monitoring and of promoting vaccination in these regions.

Association of Built Environmental Features with Rates of Infectious Diseases in Remote Indigenous Communities in the Northern Territory, Australia.

The health of Indigenous Australians is far poorer than non-Indigenous Australians, including an excess burden of infectious diseases. The health effect of built environmental (BE) features on Indigenous communities receives little attention. This study's objective was to determine associations between BE features and infectious disease incidence rates in remote Indigenous communities in the Northern Territory (NT), Australia. Remote Indigenous communities (n = 110) were spatially joined to 93 Indigenous Locations (ILOC). Outcomes data were extracted (NT Notifiable Diseases System) and expressed as ILOC-specific incidence rates. Counts of buildings were extracted from community asset maps and grouped by function. Age-adjusted infectious disease rates were dichotomised, and bivariate binomial regression used to determine the relationships between BE variables and infectious disease. Infrastructure Shelter BE features were universally associated with significantly elevated disease outcomes (relative risk 1.67 to 2.03). Significant associations were observed for Services, Arena, Community, Childcare, Oval, and Sports and recreation BE features. BE groupings associated with disease outcomes were those with communal and/or social design intent or use. Comparable BE groupings without this intent or use did not associate with disease outcomes. While discouraging use of communal BE features during infectious disease outbreaks is a conceptually valid countermeasure, communal activities have additional health benefits themselves, and infectious disease transmission could instead be reduced through repairs to infrastructure, and more infrastructure. This is the first study to examine these associations simultaneously in more than a handful of remote Indigenous communities to illustrate community-level rather than aggregated population-level associations.

The Darwin Prospective Melioidosis Study: a 30-year prospective, observational investigation.

BACKGROUND: The global distribution of melioidosis is under considerable scrutiny, with both unmasking of endemic disease in African and Pacific nations and evidence of more recent dispersal in the Americas. Because of the high incidence of disease in tropical northern Australia, The Darwin Prospective Melioidosis Study commenced in October, 1989. We present epidemiology, clinical features, outcomes, and bacterial genomics from this 30-year study, highlighting changes in the past decade. METHODS: The present study was a prospective analysis of epidemiological, clinical, and laboratory data for all culture-confirmed melioidosis cases from the tropical Northern Territory of Australia from Oct 1, 1989, until Sept 30, 2019. Cases were identified on the basis of culture-confirmed melioidosis, a laboratory-notifiable disease in the Northern Territory of Australia. Patients who were culture-positive were included in the study. Multivariable analysis determined predictors of clinical presentations and outcome. Incidence, survival, and cluster analyses were facilitated by population and rainfall data and genotyping of Burkholderia pseudomallei, including multilocus sequence typing and whole-genome sequencing. FINDINGS: There were 1148 individuals with culture-confirmed melioidosis, of whom 133 (12%) died. Median age was 50 years (IQR 38-60), 48 (4%) study participants were children younger than 15 years of age, 721 (63%) were male individuals, and 600 (52%) Indigenous Australians. All but 186 (16%) had clinical risk factors, 513 (45%) had diabetes, and 455 (40%) hazardous alcohol use. Only three (2%) of 133 fatalities had no identified risk. Pneumonia was the most common presentation occurring in 595 (52%) patients. Bacteraemia occurred in 633 (56%) of 1135 patients, septic shock in 240 (21%) patients, and 180 (16%) patients required mechanical ventilation. Cases correlated with rainfall, with 80% of infections occurring during the wet season (November to April). Median annual incidence was 20·5 cases per 100 000 people; the highest annual incidence in Indigenous Australians was 103·6 per 100 000 in 2011-12. Over the 30 years, annual incidences increased, as did the proportion of patients with diabetes, although mortality decreased to 17 (6%) of 278 patients over the past 5 years. Genotyping of B pseudomallei confirmed case clusters linked to environmental sources and defined evolving and new sequence types. INTERPRETATION: Melioidosis is an opportunistic infection with a diverse spectrum of clinical presentations and severity. With early diagnosis, specific antimicrobial therapy, and state-of-the-art intensive care, mortality can be reduced to less than 10%. However, mortality remains much higher in the many endemic regions where health resources remain scarce. Genotyping of B pseudomallei informs evolving local and global epidemiology. FUNDING: The Australian National Health and Medical Research Council.

Impact of a model of care for heart failure in-patients to reduce variation in care: a quality improvement project.

BACKGROUND: We identified variation in delivery of guideline recommended care at our institution, and undertook a project to design a heart failure (HF) model of care. AIM: To maximise time patients with HF spend well in the community by delivering best practice guidelines to reduce variation in care improving overall outcomes. METHODS: This quality improvement project focused on reducing variation in process measures of care. The HF model of care included electronic HF care bundles, a patient education pack with staff training on delivering HF patient education, referral of all HF patients to the Hospital Admissions Risk Program for phone call within 72 h, and a nurse-pharmacist early follow-up clinic. Outcomes were assessed using interrupted time series analyses. RESULTS: The pre-intervention group comprised 1585 patients, and post-intervention 1720 patients with a primary diagnosis of HF admitted under general cardiology and general medicine. Interrupted time series analysis indicated 30-day readmissions did not change in overall trend (-0.2% per month, P = 0.479) but a significant immediate step-down of 7.8% was seen (P = 0.018). For 90-day readmissions, a significant trend reduction over the time period was seen (-0.6% per month, P = 0.017) with a significant immediate step-down (-9.4%, P = 0.001). Emergency department representations, in-patient mortality and length of stay did not change significantly. Improvements in process measures were seen at audit. CONCLUSION: This model of care resulted in overall trends of reductions in 30- and 90-day readmissions, without increasing emergency department representations, mortality and length of stay. This model will be adapted as the electronic medical record is introduced at our institution.

Physical distancing and non-respiratory notifiable diseases in the Northern Territory, March-May 2020.

ABSTRACT: Strict physical distancing measures and border controls have been introduced in the Northern Territory (NT), and across Australia, to reduce the spread of coronavirus disease 2019 (COVID-19). These measures have been associated with reduced incidence of other respiratory illnesses such as influenza. It is currently unclear what effect these measures have on non-respiratory communicable diseases. The incidence of notifiable non-respiratory communicable diseases within the NT, from 15 March to 15 May 2020, the period of most restrictive physical distancing, was monitored and is here compared with two control periods: (i) the 4 months immediately prior and (ii) the same two-month period from the preceding 5 years. During the study period, there was a decline in incidence of communicable enteric illnesses, particularly in shigellosis and rotavirus where person-to-person spread is the main transmission route. There was an increase in chlamydial conjunctivitis in areas with endemic trachoma, which is under further investigation. There was no observed increase in conditions associated with crowding, such as those related to group A streptococcal infection.

Neurosyphilis: Still prevalent and overlooked in an at risk population.

BACKGROUND: Neurosyphilis (NS) presents with a variety of clinical syndromes that can be attributed to other aetiologies due to difficulties in its diagnosis. We reviewed all cases of NS from the "Top End" of the Australian Northern Territory over a ten-year period to assess incidence, clinical and laboratory manifestations. METHODS: Patient data (2007-2016) were extracted from hospital records, centralised laboratory data and Northern Territory Centre for Disease Control records. Clinical records of patients with clinically suspected NS were reviewed. A diagnosis of NS was made based on the 2014 US CDC criteria. Results were also recategorized based on the 2018 US CDC criteria. RESULTS: The population of the "Top End" is 185,570, of whom 26.2% are Indigenous. A positive TPPA was recorded in 3126 individuals. A total of 75 (2.4%) of TPPA positive patients had a lumbar puncture (LP), of whom 25 (35%) were diagnosed with NS (9 definite, 16 probable). Dementia was the most common manifestation (58.3%), followed by epilepsy (16.7%), psychosis (12.5%), tabes dorsalis (12.5%) and meningovascular syphilis (8.3%). 63% of probable NS cases were not treated appropriately due to a negative CSF VDRL. Despite increased specificity of the 2018 US CDC criteria, 70% of patient in the probable NS group were not treated appropriately. The overall annual incidence [95%CI] of NS was 2.47[1.28-4.31] per 100 000py in the Indigenous population and 0.95[0.50-1.62] in the non-Indigenous population (rate ratio = 2.60 [1.19-5.70];p = 0.017). CONCLUSION: Neurosyphilis is frequently reported in the NT, particularly in Indigenous populations. Disturbingly, 60% of probable neurosyphilis patients based on the 2014 criteria, and 70% based on the 2018 criteria with were not treated appropriately. It is critical that clinicians should be aware of the diagnosis of NS and treat patients appropriately.

The first 2 months of COVID-19 contact tracing in the Northern Territory of Australia, March-April 2020.

The Northern Territory (NT) Centre for Disease Control (CDC) undertook contact tracing of all notified cases of coronavirus disease 2019 (COVID-19) within the Territory. There were 28 cases of COVID-19 notified in the NT between 1 March and 30 April 2020. In total 527 people were identified as close contacts over the same period; 493 were successfully contacted; 445 were located in the NT and were subsequently quarantined and monitored for disease symptoms daily for 14 days after contact with a confirmed COVID-19 case. Of these 445 close contacts, 4 tested positive for COVID-19 after developing symptoms; 2/46 contacts who were cruise ship passengers (4.3%, 95% CI 0.5-14.8%) and 2/51 household contacts (3.9%, 95% CI 0.5-13.5%). None of the 326 aircraft passengers or 4 healthcare workers who were being monitored in the NT as close contacts became cases.

Epidemiological trends in notified influenza cases in Australia's Northern Territory, 2007-2016.

BACKGROUND: The Northern Territory (NT) of Australia has a mix of climates, sparsely distributed population and a large proportion of the populace are Indigenous Australians, and influenza is known to have a disproportionate impact upon this group. Understanding the epidemiology of influenza in this region would inform public health strategies. OBJECTIVES: To assess if there are consistent patterns in characteristics of influenza outbreaks in the NT. METHODS: Laboratory confirmed influenza cases in the NT are notified to the NT Centre for Disease Control. We conducted analyses on notified cases from 2007-2016 to determine incidence rates (by age group, Indigenous status and area), seasonality of cases and spatial distribution of influenza types. Notified cases were linked to laboratory datasets to update information on influenza type or subtype RESULTS: The disparity in Indigenous and non-Indigenous notification rates varied by age group, with rate ratios for Indigenous versus non-Indigenous ranging from 1.58 (95% CI:1.39, 1.80) for ages 15-24 to 5.56 (95% CI: 4.71, 6.57) for ages 55-64. The disparity between Indigenous and non-Indigenous notification rates appeared higher in the Central Australia region. Indigenous versus non-Indigenous hospitalisation and mortality rate ratios were 6.51 (95% CI: 5.91, 7.18) and 5.46 (95% CI: 2.40, 12.71) respectively. Inter-seasonal peaks during February and March occurred in 2011, 2013 and 2014, and were due to influenza activity in the tropical north of the NT. CONCLUSIONS: Our results highlight the importance of influenza vaccination across all age groups for Indigenous Australians. An early vaccination campaign targeted against outbreaks in February-March would be best focused on the tropical north.

Intense interseasonal influenza outbreaks, Australia, 2018/19.

BackgroundInterseasonal influenza outbreaks are not unusual in countries with temperate climates and well-defined influenza seasons. Usually, these are small and diminish before the main influenza season begins. However, the 2018/19 summer-autumn interseasonal influenza period in Australia saw unprecedented large and widespread influenza outbreaks.AimOur objective was to determine the extent of the intense 2018/19 interseasonal influenza outbreaks in Australia epidemiologically and examine the genetic, antigenic and structural properties of the viruses responsible for these outbreaks.MethodsThis observational study combined the epidemiological and virological surveillance data obtained from the Australian Government Department of Health, the New South Wales Ministry of Health, sentinel outpatient surveillance, public health laboratories and data generated by the World Health Organization Collaborating Centre for Reference and Research on Influenza in Melbourne and the Singapore Agency for Science, Technology and Research.ResultsThere was a record number of laboratory-confirmed influenza cases during the interseasonal period November 2018 to May 2019 (n= 85,286; 5 times the previous 3-year average) and also more institutional outbreaks, hospitalisations and deaths, than what is normally seen.ConclusionsThe unusually large interseasonal influenza outbreaks in 2018/19 followed a mild 2018 influenza season and resulted in a very early start to the 2019 influenza season across Australia. The reasons for this unusual event have yet to be fully elucidated but are likely to be a complex mix of climatic, virological and host immunity-related factors. These outbreaks reinforce the need for year-round surveillance of influenza, even in temperate climates with strong seasonality patterns.

Prevalence and impact of non-cardiovascular comorbidities among older adults hospitalized for non-ST segment elevation acute coronary syndrome.

BACKGROUND: There is a paucity of information on the prognostic importance of non-cardiovascular comorbidities (NCCs) among patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). This study examined the prevalence and impact of NCCs on the length of stay (LOS) and mortality among older adults hospitalized for NSTE-ACS. METHODS: Among 1,488 older adults (mean age 79.4±8.4 years; 62.0% male) hospitalized for NSTE-ACS at a tertiary hospital in Melbourne, Australia, during 2013-2015, we collected data on comorbidities, LOS, and discharge outcomes. Thirteen NCCs were studied. Negative binomial and Cox proportional regression models were applied to examine the association between NCCs and LOS and in-hospital death, respectively. RESULTS: Approximately 53% of the patients had ≥1 NCCs. Diabetes and renal disease as well as anemia and renal disease co-existed more frequently than expected. Compared to having no NCCs, having one NCC was not associated with a significant increase in the likelihood of longer LOS [incidence rate ratio (IRR) 1.07; 95% CI: 0.99-1.15; P=0.085] or in-hospital death [hazard ratio (HR) 1.11; 95% CI: 0.65-1.90; P=0.707]. However, having ≥2 NCCs was associated with 22% and 79% increased likelihood of longer LOS (IRR 1.22, 95% CI: 1.11-1.33; P<0.001) and in-hospital death (HR 1.79, 95% CI: 1.06-3.03; P=0.029), respectively, compared to not having any NCC. Certain NCC dyads [e.g., chronic pulmonary disease (CPD) + renal disease] exhibited multiplicative effect such that their impact on patients' LOS or survival exceeded the sum of the individual effects of the component NCCs. CONCLUSIONS: Over half of older patients hospitalized with NSTE-ACS had NCCs. A higher burden of NCCs correlated with increased LOS and lower survival. Contemporary ACS management guidelines need to recognize and incorporate protocols for the treatment of individuals with multiple chronic conditions to reduce the occurrence of adverse outcomes.

Effect of Comorbidity Assessed by the Charlson Comorbidity Index on the Length of Stay, Costs and Mortality among Older Adults Hospitalised for Acute Stroke.

The burden of comorbidity among stroke patients is high. The aim of this study was to examine the effect of comorbidity on the length of stay (LOS), costs, and mortality among older adults hospitalised for acute stroke. Among 776 older adults (mean age 80.1 ± 8.3 years; 46.7% female) hospitalised for acute stroke during July 2013 to December 2015 at a tertiary hospital in Melbourne, Australia, we collected data on LOS, costs, and discharge outcomes. Comorbidity was assessed via the Charlson Comorbidity Index (CCI), where a CCI score of 0⁻1 was considered low and a CCI ≥ 2 was high. Negative binomial regression and quantile regression were applied to examine the association between CCI and LOS and cost, respectively. Survival was evaluated with the Kaplan⁻Meier and Cox regression analyses. The median LOS was 1.1 days longer for patients with high CCI than for those with low CCI. In-hospital mortality rate was 18.2% (22.1% for high CCI versus 11.8% for low CCI, p < 0.0001). After controlling for confounders, high CCI was associated with longer LOS (incidence rate ratio [IRR]; 1.35, p < 0.0001) and increased likelihood of in-hospital death (hazard ratio [HR]; 1.91, p = 0.003). The adjusted median, 25th, and 75th percentile costs were AUD$2483 (26.1%), AUD$1446 (28.1%), and AUD$3140 (27.9%) higher for patients with high CCI than for those with low CCI. Among older adults hospitalised for acute stroke, higher global comorbidity (CCI ≥ 2) was associated adverse clinical outcomes. Measures to better manage comorbidities should be considered as part of wider strategies towards mitigating the social and economic impacts of stroke.

Australian vaccine preventable disease epidemiological review series: varicella-zoster virus infections, 1998-2015.

INTRODUCTION: In 2005, the National Immunisation Program implemented a varicella vaccine for children aged 18 months, and in 2016, a herpes zoster (HZ) vaccine for adults aged 70-79 years. This epidemiological review analyses national trends in varicella and HZ for the years 1998-2015 to examine the impact of a funded varicella vaccine and provide a baseline for monitoring the impact of a funded HZ vaccine. METHODS: Varicella and HZ notifications (2002-2015), hospitalisations (1999-2013) and deaths (1998-2013) were sourced. We stratified analyses by age, sex and Indigenous status, and estimated rates and incidence rate ratios. RESULTS: Funded varicella vaccine led to a rapid decline in varicella notifications, hospitalisations and deaths. During the post-varicella vaccine period, hospitalisations declined in all age groups <40 years, with greatest reduction of 84% in children aged 18-59 months. Annual HZ hospitalisation rate was 10.8 per 100,000. HZ hospitalisation rates increased with age and were highest in persons aged =75 years (87.6 per 100,000). Post-herpetic neuralgia (PHN) was diagnosed in 32.5% HZ hospitalisations with highest hospitalisation rate in persons aged =75 years (32.1 per 100,000). Varicella and HZ hospitalisation rates were significantly higher among Indigenous Australians. Twenty one deaths were coded as due to varicella and 340 deaths were coded as due to HZ in persons aged <40 years and =40 years, respectively. CONCLUSIONS: The national varicella immunisation program substantially reduced varicella associated morbidity and mortality. Burden of HZ and PHN in Australia is substantial. Following the introduction of a funded HZ vaccine, timely and high quality surveillance will be crucial to assess the impact of the national HZ immunisation program.

An outbreak of Salmonella Saintpaul gastroenteritis after attending a school camp in the Northern Territory, Australia.

An outbreak of salmonellosis occurred following attendance at a school camp between 5 and 8 August 2014 in a remote area of the Northern Territory, Australia. We conducted a retrospective cohort study via telephone interviews, using a structured questionnaire that recorded symptoms and exposures to foods and activities during the camp. A case was anyone with laboratory confirmed Salmonella Saintpaul infection or a clinically compatible illness after attending the camp. Environmental health officers from the Environmental Health Branch undertook an investigation and collected water and environmental samples. We interviewed 65 (97%) of the 67 people who attended the camp. There were 60 students and 7 adults. Of the 65 people interviewed, 30 became ill (attack rate 46%); all were students; and 4 had laboratory confirmed S. Saintpaul infection. The most commonly reported symptoms were diarrhoea (100% 30/30), abdominal pain (93% 28/30), nausea (93% 28/30) and fever (70% 21/30). Thirteen people sought medical attention but none required hospitalisation. Illness was significantly associated with drinking cordial at lunch on 7 August (RR 3.8, 95% CI 1.3-11, P < 0.01), as well as drinking cordial at lunch on 8 August (RR 2.1, 95% CI 1.1-4.2, P=0.01). Salmonella spp. was not detected in water samples or wallaby faeces collected from the camp ground. The epidemiological investigation suggests the outbreak was caused by environmental contamination of food or drink and could have occurred during ice preparation or storage, preparation of the cordial or from inadequate sanitising of the cooler from which the cordial was served. This outbreak highlights the risks of food or drink contamination with environmental Salmonella. Those preparing food and drink in campground settings should be vigilant with cleaning, handwashing and disinfection to prevent outbreaks of foodborne disease.

An outbreak of salmonellosis associated with duck prosciutto at a Northern Territory restaurant.

In June 2015, an outbreak of salmonellosis occurred among people who had eaten at a restaurant in Darwin, Northern Territory over 2 consecutive nights. We conducted a retrospective cohort study of diners who ate at the restaurant on 19 and 20 June 2015. Diners were telephoned and a questionnaire recorded symptoms and menu items consumed. An outbreak case was defined as anyone with laboratory confirmed Salmonella Typhimurium PT9 (STm9) or a clinically compatible illness after eating at the restaurant. Environmental health officers inspected the premises and collected food samples. We contacted 79/83 of the cohort (response rate 95%); 21 were cases (attack rate 27%), and 9 had laboratory confirmed STm9 infection. The most commonly reported symptoms were diarrhoea (100%), abdominal pain (95%), fever (95%) and nausea (95%). Fifteen people sought medical attention and 7 presented to hospital. The outbreak was most likely caused by consumption of duck prosciutto, which was consumed by all cases (OR 18.6, CI 3.0-∞, P < 0.01) and was prepared on site. Salmonella was not detected in any food samples but a standard plate count of 2 x 107 colony forming units per gram on samples of duck prosciutto demonstrated bacterial contamination. The restaurant used inappropriate methodology for curing the duck prosciutto. Restaurants should consider purchasing pre-made cured meats, or if preparing them on site, ensure that they adhere to safe methods of production.

Prevention of perinatal hepatitis B virus transmission: are we following guidelines?

It is recommended that infants born to women with hepatitis B infection should have serological review following completion of a four dose vaccination schedule. A review was undertaken on 102 neonates who received hepatitis B immunoglobulin to ascertain the proportion that were fully immunised and then followed up. Of the 66 infants for whom data were available, 65 (98.5%) had appropriately received four doses of hepatitis B vaccine in infancy and a further child had received three doses. Only 19/66 (29%; 95%CI: 18-41%) infants had documented follow-up serology results, one of whom was infected and one of whom was immune through clearance of infection. All children who had no serology documented were traced and offered testing in primary care. Our results demonstrate that although adherence to the vaccination schedule in this group of infants was good, mechanisms for ensuring that infants receive serology testing need to be strengthened.

Investigation into High Barmah Forest Virus Disease Case Numbers Reported in the Northern Territory, Australia in 2012-2013.

Between October 2012 and October 2013, unprecedented high numbers of Barmah Forest virus (BFV) disease cases were reported in the Northern Territory (NT). An investigation was launched by the NT Department of Health in cooperation with the Department of Primary Industry and Fisheries and the Department of Land Resource Management to investigate possible causes for this phenomenon. The investigation included virus isolations from mosquitoes collected in Darwin urban areas, BFV antibody testing in peri-urban small mammals and a human BFV disease case series investigation of recent cases. No BFV was isolated from the 4641 mosquitoes tested, none of the mammals tested positive for BFV antibodies, and the high BFV disease case numbers did not correlate with the relatively low mosquito vector numbers trapped in 2012-2013. It was estimated that up to 89% of the 79 human cases investigated did not have an acute arboviral illness and therefore had tested falsely positive. An Alere PanBio BFV immunoglobulin M enzyme-linked immunosorbent assay test kit is generally used to test for BFV, with the BFV disease case definition based on immunoglobulin M positives only. Other jurisdictions in Australia also reported high numbers of BFV disease cases, with the majority of the cases suspected to be false positives. Therefore, current testing methods need to be revised to reflect the true numbers of BFV disease cases occurring in Australia and to provide correct diagnoses for patients.

Salmonella in the tropical household environment--Everyday, everywhere.

OBJECTIVES: To determine the prevalence of Salmonella in the environment of case and control houses, and compare serovars isolated from cases and their houses. METHODS: From 2005 to 2008, we tested samples from houses of 0-4 year old cases and community controls in Darwin and Palmerston for Salmonella. Case isolates were compared with environmental isolates. S. Ball and S. Urbana isolates were compared using Multiple Amplification of Phage Locus Typing (MAPLT) and Multiple-Locus Variable number of tandem repeat Analysis (MLVA). RESULTS: Salmonella were found in 47/65 (72%) case houses and 18/29 (62%) control houses; these proportions were not significantly different. In 21/47 (45%) houses, case and environmental isolates (from animal faeces, soil and vacuums) were indistinguishable. Multiple serovars were isolated from 20 (31%) case and 6 (21%) control houses. All but one environmental isolate are known human pathogens in the Northern Territory (NT). Each of the four pairs of S. Ball and S. Urbana were indistinguishable. CONCLUSIONS: Animal faeces were the most likely source of salmonellosis in cases. The similar prevalence of house isolates suggests that Salmonella is ubiquitous in this environment. The distinction of S. Ball and S. Urbana subtypes enabled linkage of human illness to environmental exposure. Environmental contamination with Salmonella is an important source of sporadic infection in children in the tropics.

The changing epidemiology of Murray Valley encephalitis in Australia: the 2011 outbreak and a review of the literature.

Murray Valley encephalitis virus (MVEV) is the most serious of the endemic arboviruses in Australia. It was responsible for six known large outbreaks of encephalitis in south-eastern Australia in the 1900s, with the last comprising 58 cases in 1974. Since then MVEV clinical cases have been largely confined to the western and central parts of northern Australia. In 2011, high-level MVEV activity occurred in south-eastern Australia for the first time since 1974, accompanied by unusually heavy seasonal MVEV activity in northern Australia. This resulted in 17 confirmed cases of MVEV disease across Australia. Record wet season rainfall was recorded in many areas of Australia in the summer and autumn of 2011. This was associated with significant flooding and increased numbers of the mosquito vector and subsequent MVEV activity. This paper documents the outbreak and adds to our knowledge about disease outcomes, epidemiology of disease and the link between the MVEV activity and environmental factors. Clinical and demographic information from the 17 reported cases was obtained. Cases or family members were interviewed about their activities and location during the incubation period. In contrast to outbreaks prior to 2000, the majority of cases were non-Aboriginal adults, and almost half (40%) of the cases acquired MVEV outside their area of residence. All but two cases occurred in areas of known MVEV activity. This outbreak continues to reflect a change in the demographic pattern of human cases of encephalitic MVEV over the last 20 years. In northern Australia, this is associated with the increasing numbers of non-Aboriginal workers and tourists living and travelling in endemic and epidemic areas, and also identifies an association with activities that lead to high mosquito exposure. This outbreak demonstrates that there is an ongoing risk of MVEV encephalitis to the heavily populated areas of south-eastern Australia.