Investigation and response to an outbreak of Neisseria meningitidis serogroup Y ST-1466 urogenital infections, Australia

Abstract

In 2023, an increased number of urogenital and anorectal infections with Neisseria meningitis serogroup Y (MenY) were reported in New South Wales (NSW). Whole genome sequencing (WGS) found a common sequence type (ST-1466), with limited sequence diversity. Confirmed outbreak cases were NSW residents with a N. meningitidis isolate matching the cluster sequence type; probable cases were NSW residents with MenY isolated from a urogenital or anorectal site from 1 July 2023 without WGS testing. Of the 41 cases, most were men (n = 27), of whom six reported recent contact with a female sex worker. Five cases were men who have sex with men and two were female sex workers. Laboratory alerts regarding the outbreak were sent to all Australian jurisdictions through the laboratories in the National Neisseria Network. Two additional states identified urogenital MenY ST-1466 infections detected in late 2023. Genomic analysis showed all MenY ST-1466 sequences were interspersed, suggestive of an Australia-wide outbreak. The incidence of these infections remains unknown, due to varied testing and reporting practices both within and across jurisdictions. Isolates causing invasive meningococcal disease (IMD) in Australia are typed, and there has been no MenY ST-1466 IMD recorded in Australia to end of March 2024. Concerns remain regarding the risk of IMD, given the similarity of these sequences with a MenY ST-1466 IMD strain causing a concurrent outbreak in the United States of America.

The value of universal screening for COVID-19 cases on cruise ships during outbreaks

OBJECTIVES

To describe the impact of universal screening for coronavirus disease 2019 (COVID-19) on passengers on cruise ships docking in Sydney, Australia, during 2022 that experienced a significant outbreak of COVID-19. Type of program or service: Cruise ship disease surveillance Methods: Case series, based on analysis of cruise ship voyages where universal screening of passengers was requested by a NSW health authority and undertaken by the cruise ship.

RESULTS

Of 111 voyages in 2022, three fit the definition for this study. Universal screening during these voyages resulted in the detection of up to 1.8 times the number of existing COVID-19 cases, increasing attack rates of the three voyages from 14% to 24%; 13% to 28%; and 3% to 8% respectively. Case demographics showed an even gender distribution, with a majority 70 years or older. Asymptomatic case percentage ranged from 2% to 54%, with age and gender not associated with symptomatic status. Almost all cases were reported as being fully vaccinated. Genomic testing of cases showed multiple lineages of COVID-19 circulating in all three voyages.

LESSONS LEARNT

Public health authorities, the cruise industry and passengers should be aware that a large number of unidentified cases of COVID-19 may disembark from a cruise ship that has experienced a large outbreak of the virus. These cases can seed the infection into vulnerable communities. Universal screening as part of the response to a significant outbreak will help identify cases and limit the spread of COVID-19.

Community Outbreak of Pseudomonas aeruginosa Infections Associated with Contaminated Piercing Aftercare Solution, Australia, 2021

In April 2021, the South Eastern Sydney Local Health District Public Health Unit (Sydney, New South Wales, Australia) was notified of 3 patients with Pseudomonas aeruginosa infections secondary to skin piercings performed at the same salon. Active case finding through laboratories, clinician alerts, and monitoring hospital visits for piercing-related infections identified additional cases across New South Wales, and consumers were alerted. We identified 13 confirmed and 40 probable case-patients and linked clinical isolates by genomic sequencing. Ten confirmed case-patients had used the same brand and batch of aftercare solution. We isolated P. aeruginosa from opened and unopened bottles of this solution batch that matched the outbreak strain identified by genomic sequencing. Piercing-related infections returned to baseline levels after this solution batch was recalled. Early outbreak detection and source attribution via genomic sequencing are crucial for controlling outbreaks linked to contaminated products. Manufacturing standards for nonsterile cosmetic products and guidance for piercing aftercare warrant review.

First documented gymnasium cluster of COVID-19 with whole genome sequencing in Australia

Background

Transmission of coronavirus disease 2019 (COVID-19) has been demonstrated in fitness settings internationally. We report the first documented case of transmission of COVID-19 in a gymnasium in Australia in 2020.

Methods

Case finding and case interviews were conducted among attendees in a Western Sydney gymnasium, Australia. Whole genome sequencing using an amplicon-based approach was performed on all SARS CoV-2 polymerase chain reaction positive samples detected through surveillance.

Results

We show that five cases of COVID-19 were linked to the gymnasium, with transmission occurring on 7 July 2020, when the index case transmitted the infection to four other gymnasium attendees through the sharing of an enclosed space.

Conclusions

There is an ongoing risk of transmission of COVID-19 within gymnasium environments and they are justifiably classified as a 'high-risk' venue. There may be a need to expand ventilation and space requirements to prevent transmission of COVID-19 in such settings in the context of severe COVID-19 variants or to prevent respiratory disease transmission in general.

Investigation of a legionellosis outbreak in Sydney CBD - a brief report

OBJECTIVE

To identify and control a source of Legionella in Sydney CBD.

METHODS

Clinical, epidemiological, environmental and genomic techniques were employed to identify cases and the source of Legionella.

RESULTS

Eleven legionellosis cases were linked to Sydney CBD with a median age of 69 years. All were hospitalised and had risk factors for Legionella infection. Eight of 11 cases identified as male. Genomic analysis linked three cases to a contaminated cooling water source in Sydney CBD, with a further case infected with a similar strain to that found in Sydney CBD. Another case, although epidemiologically linked to Sydney CBD, was infected with a genomically different strain to that found in Sydney CBD. Six other cases had no viable sample for genomic analysis.

CONCLUSION/IMPLICATIONS FOR PUBLIC HEALTH

An outbreak of legionellosis is a serious public health threat that requires rapid investigation and environmental control. We were able to identify a source in Sydney CBD through the application of clinical, epidemiological, environmental and genomic techniques. Genomic analysis is a powerful tool that can be used to confirm the source location but requires close collaboration between clinicians, public health units and microbiologists to recover viable sputum cultures from cases diagnosed with legionellosis.

The value of active follow up of a newly acquired hepatitis B infection – lessons for current approaches

The standard practice of blood borne virus (BBV) follow-up in New South Wales is a passive approach of general-practitioner-led testing. The value of this approach is unknown. We undertook an active contact tracing method with the aims of investigating a potential hepatitis B source, along with accurately measuring the participation rate, to consider the value of this and other follow-up methods for future BBV investigations. Investigation of a newly-acquired hepatitis B infection was undertaken at a dental practice identified as a possible exposure site. To screen for hepatitis B infection among potential source or co-exposed clients, we actively followed up with staff and clients of the practice to request they undertake hepatitis B serology. Eligible staff and clients received up to four phone calls and were provided with a pathology request form by the public health unit (PHU). Access to free serology was offered to people who did not have access to Medicare. Reminder calls were made if serology results were not received by the PHU. As the ordering doctor, the public health physician was responsible for providing results and referring for follow-up care. Of 160 clients, 63 (39%) undertook hepatitis B serology. Of these 63, none were found to have hepatitis B infection. It was estimated the active investigation involved an extra 430 hours of PHU staff time at a cost in Australian dollars of $30,000. Active follow-up allows an accurate participation rate to be documented. Despite intense active follow-up, only 39% of clients undertook testing, bringing into question the yield of the usual approach in which active follow-up of potential mass BBV exposures is not undertaken. While active follow-up is resource intensive, it should be considered where the risks and consequences from the BBV infection are high.

Estimating the excess burden of pertussis disease in Australia within the first year of life, that might have been prevented through timely vaccination

BACKGROUND

Previous Australian studies have shown that delayed vaccination with each of the three primary doses of diphtheria-tetanus-pertussis-containing vaccines (DTP) is up to 50 % in certain subpopulations. We estimated the excess burden of pertussis that might have been prevented if (i) all primary doses and (ii) each dose was given on time.

METHODS

Perinatal, immunization, pertussis notification and death data were probabilistically linked for 1 412 984 infants born in two Australian states in 2000-12. A DTP dose administered >15 days after the recommended age was considered delayed. We used Poisson regression models to compare pertussis notification rates to 1-year of age in infants with ≥1 dose delayed (Aim 1) or any individual dose delayed (Aim 2) versus a propensity weighted counterfactual on-time cohort.

RESULTS

Of all infants, 42% had ≥1 delayed DTP dose. We estimated that between 39 to 365 days of age, 85 (95% CI: 61-109) cases per 100 000 infants, could have been prevented if all infants with ≥1 delayed dose had received their three doses within the on-time window. Risk of pertussis was higher in the delayed versus the on-time cohort, so crude rates overestimated the excess burden (110 cases per 100 000 infants (95% CI: 95-125)). The estimated dose-specific excess burden per 100 000 infants was 132 for DTP1, 50 for DTP2 and 19 for DTP3.

CONCLUSIONS

We provide robust evidence that improved DTP vaccine timeliness, especially for the first dose, substantially reduces the burden of infant pertussis. Our methodology, using a potential outcomes framework, is applicable to other settings.

The suitability and usability of a tool to assess contact status from COVID-19 exposures in the workplace

OBJECTIVE

To assess the usability of a self-assessment COVID-19 exposure tool for workplaces.

METHODS

A COVID-19 exposure tool for workplaces was developed using five risk criteria. Public Health Unit (PHU) assessors who administered the tool documented when they administered the tool, the time taken for finalisation of the assessment and ease of administration. The System Usability Scale was used for workplace managers' perceptions on tool use. Data were assessed using both quantitative and qualitative analysis.

RESULTS

Eighty-four workplaces used the tool to assess COVID-19 exposure risk. Of those, the outcome provided by the tool did not require modification by the PHU assessor in 70% of workplaces. Eighty per cent of the assessments were completed by the next day. PHU assessors rated the overall ease of administration of the tool as 'easy' or 'very easy' for 85% of workplaces and indicated they would employ the tool across a number of settings including complex workplaces. The mean System Usability Scale was 82. Workplace managers were predominately positive regarding its suitability.

CONCLUSION

The tool provides an easy-to-use assessment of SARS-CoV-2 exposure in the workplace.

IMPLICATIONS FOR PUBLIC HEALTH

The tool's adoption will empower workplace managers and improve the capacity of public health units to prevent further transmission of SARS-CoV-2 in workplaces.

Measuring school level attributable risk to support school-based HPV vaccination programs

Background

In Australia in 2017, 89% of 15-year-old females and 86% of 15-year-old males had received at least one dose of the HPV vaccine. However, considerable variation in HPV vaccination initiation (dose one) across schools remains. It is important to understand the school-level characteristics most strongly associated with low initiation and their contribution to the overall between-school variation.

Methods

A population-based ecological analysis was conducted using school-level data for 2016 on all adolescent students eligible for HPV vaccination in three Australian jurisdictions. We conducted logistic regression to determine school-level factors associated with lower HPV vaccination initiation (< 75% dose 1 uptake) and estimated the population attributable risk (PAR) and the proportion of schools with the factor (school-level prevalence).

Results

The factors most strongly associated with lower initiation, and their prevalence were; small schools (OR = 9.3, 95%CI = 6.1–14.1; 33% of schools), special education schools (OR = 5.6,95%CI = 3.7–8.5; 8% of schools), higher Indigenous enrolments (OR = 2.7,95% CI:1.9–3.7; 31% of schools), lower attendance rates (OR = 2.6,95%CI = 1.7–3.7; 35% of schools), remote location (OR = 2.6,95%CI = 1.6–4.3; 6% of schools,) and lower socioeconomic area (OR = 1.8,95% CI = 1.3–2.5; 33% of schools). The highest PARs were small schools (PAR = 79%, 95%CI:76–82), higher Indigenous enrolments (PAR = 38%, 95%CI: 31–44) and lower attendance rate (PAR = 37%, 95%CI: 29–46).

Conclusion

This analysis suggests that initiatives to support schools that are smaller, with a higher proportion of Indigenous adolescents and lower attendance rates may contribute most to reducing the variation of HPV vaccination uptake observed at a school-level in these jurisdictions. Estimating population-level coverage at the school-level is useful to guide policy and prioritise resourcing to support school-based vaccination programs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13088-x.

School-Level Variation in Coverage of Co-Administered dTpa and HPV Dose 1 in Three Australian States

BACKGROUND

Australian adolescents are routinely offered HPV and dTpa (diphtheria, tetanus, pertussis) vaccines simultaneously in the secondary school vaccination program. We identified schools where HPV initiation was lower than dTpa coverage and associated school-level factors across three states.

METHODS

HPV vaccination initiation rates and dTpa vaccination coverage in 2016 were calculated using vaccine databases and school enrolment data. A multivariate analysis assessed sociodemographic and school-level factors associated with HPV initiation being >5% absolute lower than dTpa coverage.

RESULTS

Of 1280 schools included, the median school-level HPV initiation rate was 85% (interquartile range (IQR):75-90%) and the median dTpa coverage was 86% (IQR:75-92%). Nearly a quarter (24%) of all schools had HPV vaccination initiation >5% lower than dTpa coverage and 11 % had >10% difference. School-level factors independently associated with >5% difference were remote schools (aOR:3.5, 95% CI = 1.7-7.2) and schools in major cities (aOR:1.8, 95% CI = 1.0-3.0), small schools (aOR:3.3, 95% CI = 2.3-5.7), higher socioeconomic advantage (aOR:1.7, 95% CI = 1.1-2.6), and lower proportions of Language-background-other-than-English (aOR:1.9, 95% CI = 1.2-3.0).

CONCLUSION

The results identified a quarter of schools had lower HPV than dTpa initiation coverage, which may indicate HPV vaccine hesitancy, and the difference was more likely in socioeconomically advantaged schools. As hesitancy is context specific, it is important to understand the potential drivers of hesitancy and future research needs to understand the reasons driving differential uptake.

Risk factors leading to COVID-19 cases in a Sydney restaurant

OBJECTIVE

To explore the factors associated with the transmission of SARS-CoV-2 to patrons of a restaurant.

METHODS

A retrospective cohort design was undertaken, with spatial examination and genomic sequencing of cases. The cohort included all patrons who attended the restaurant on Saturday 25 July 2020. A case was identified as a person who tested positive to a validated specific Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) nucleic acid test. Associations were tested using chi-squared analysis of case versus non-case behaviours.

RESULTS

Twenty cases were epidemiologically linked to exposure at the restaurant on 25 July 2020. All cases dined indoors. All cases able to be genomic sequenced were found to have the same unique mutational profile. Factors tested for an association to the outcome included attentiveness by staff, drink consumption, bathroom use and payment by credit card. No significant results were found.

CONCLUSION

Indoor dining was identified as a key factor in SARS-CoV-2 transmission, and outdoor dining as a way to limit transmission. Implications for public health: This investigation provides empirical evidence to support public health policies regarding indoor dining.

Differences in school factors associated with adolescent HPV vaccination initiation and completion coverage in three Australian states

BACKGROUND

Schools are the primary setting for the delivery of adolescent HPV vaccination in Australia. Although this strategy has achieved generally high vaccination coverage, gaps persist for reasons that are mostly unknown. This study sought to identify school-level correlates of low vaccination course initiation and completion in New South Wales, Tasmania, and Western Australia to inform initiatives to increase uptake.

METHODS

Initiation was defined as the number of first doses given in a school in 2016 divided by vaccine-eligible student enrolments. Completion was the number of third doses given in a school in 2015-2016 divided by the number of first doses. Low initiation and completion were defined as coverage ≤ 25thpercentile of all reporting schools. We investigated correlations between covariates using Spearman's rank correlation coefficients. Due to multicollinearity, we used univariable logistic regression to investigate associations between school characteristics and low coverage.

RESULTS

Median initiation was 84.7% (IQR: 75.0%-90.4%) across 1,286 schools and median completion was 93.8% (IQR: 86.0%-97.3%) across 1,295 schools. There were strong correlations between a number of school characteristics, particularly higher Indigenous student enrolments and lower attendance, increasing remoteness, higher postcode socioeconomic disadvantage, and smaller school size. Characteristics most strongly associated with low initiation in univariate analyses were small school size, location in Tasmania, and schools catering for special educational needs. Low completion was most strongly associated with schools in Tasmania and Western Australia, remote location, small size, high proportion of Indigenous student enrolments, and low attendance rates.

CONCLUSION

This study provides indicative evidence that characteristics of schools and school populations are associated with the likelihood of low initiation and completion of the HPV vaccination course. The findings will guide further research and help target initiatives to improve vaccination uptake in schools with profiles associated with lower coverage.

Drivers of the summer influenza epidemic in New South Wales, 2018-19

OBJECTIVES

To assess the extent to which the 2018-19 New South Wales summer influenza epidemic was associated with overseas or domestic travel and with seasonal influenza vaccination status.

DESIGN, SETTING

Unmatched case-control study, based on an online survey distributed from the NSW Notifiable Conditions Information Management System (NCIMS) to people for whom mobile phone numbers were available.

PARTICIPANTS

A case was defined as a person with notified laboratory-confirmed influenza with onset of illness between 1 December 2018 and 21 March 2019. People with notified pertussis infections (confirmed or probable) were selected as controls.

MAIN OUTCOME MEASURES

Notified influenza infection, by travel and contact with unwell overseas travellers in the week before onset of illness and seasonal influenza vaccination status (as the primary exposures).

RESULTS

Valid survey responses were provided by 648 of 2806 invited people with notified influenza (23%) and 257 of 796 invited people with notified pertussis (32%). The demographic characteristics of the respondents were similar to those of the source population (7251 cases, 2254 controls). During the first two months of the summer of 2018-19, notified influenza was more likely for people who had travelled overseas or had contact with an ill overseas traveller in the week before symptom onset (adjusted OR [aOR], 6.99; 95% CI, 3.59-13.6), but not during the second two months (aOR, 1.63; 95% CI, 0.79-3.35). Influenza vaccination status was not associated with the likelihood of notified influenza.

CONCLUSIONS

Travel-related factors were early drivers of the 2018-19 NSW summer influenza epidemic; local transmission sustained the outbreak despite unfavourable conditions later in summer. Our findings prompted re-evaluation of recommendations for pre-travel vaccination in NSW. The role of travel in out-of-season influenza outbreaks should be considered in other temperate zones.

Bondi and beyond. Lessons from three waves of COVID-19 from 2020

OBJECTIVES

To describe local operational aspects of the coronavirus disease 2019 (COVID-19) response during the first three waves of outbreaks in New South Wales (NSW), Australia, which began in January, July and December 2020. Type of program or service: Public health outbreak response.

METHODS

Narrative with epidemiological linking and genomic testing.

RESULTS

Epidemiological linking and genomic testing found that during the first wave of COVID-19 in NSW, a large number of community transmissions went undetected because of limited testing for the virus and limited contact tracing of cases. The second wave of COVID-19 in NSW emerged following reintroduction from the second wave in Victoria, Australia in July 2020, and the third wave followed undetected introduction from overseas. By the second and third waves, cases could be more effectively detected and isolated through an increased ability to test and contact trace, and to rapidly genomic sequence severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolates, allowing most cases to be identified and epidemiologically linked. This greater certainty in understanding chains of transmission resulted in control of the outbreaks despite less stringent restrictions on the community, by using a refined strategy of targeted shutdown, restrictions on cases, their close contacts, identified hotspots and venues of concern rather than a whole of community lockdown. Risk assessments of potential transmission sites were constantly updated through our evolving experience with transmission events. However, this refined strategy did leave the potential for large point source outbreaks should any cases go undetected. [Addendum] A fourth wave that began in Sydney in June 2021 challenged this strategy due to the more transmissible nature of the Delta variant of SARS-CoV-2.

LESSONS LEARNT

A wave of COVID-19 infections can develop quickly from one infected person. The community needs to remain vigilant, adhering to physical distancing measures, signing in to venues they visit, and getting tested if they have any symptoms. Signing out of venues on exit allows public health resources to be used more efficiently to respond to outbreaks.

473Preventable pertussis burden in Australia within the first year of life by improving vaccination timeliness

Background

Previous Australian studies have shown that on-time Diphtheria-Tetanus-Pertussis (DTP) vaccination coverage is 50-60% in certain subpopulations. We estimated the potentially preventable burden of pertussis if, 1) the full primary course and, 2) each dose was given on-time.

Methods

Perinatal, immunisation, pertussis notification, and death data were linked for 1,412,984 infants born in two Australian states in 2000-2012. A DTP dose administered &gt;15 days after the recommended age was categorised as delayed. For aim 1, pertussis rates up to 1-year of age were compared in infants with ≥1 dose delayed versus all doses on-time, using Poisson regression methods. For aim 2, the expected number of cases preventable by each dose was calculated as the product of the number of cases observed during the period of delay and (1 – dose-specific vaccine effectiveness).

Results

58% of infants had all primary DTP doses on time. We estimated that 85 (95% CI: 61-109) cases per 100,000 infants, aged 39-days to 1-year, could have been prevented if all infants had been vaccinated on time; 77% of these infants had received ≥1 DTP dose within the first year of life. Estimated preventable burden attributable to delayed DTP1 (58/100,000) was higher than for DTP2 (26/100,000) and DTP3 (15/100,000).

Conclusions and Key messages

Poor vaccine timeliness, especially delayed DTP1, is a key contributor to the residual burden of pertussis. These findings can inform cost-benefit analyses of targeted programs and public health messaging to reduce delays.

Childhood vaccination coverage in Australia: an equity perspective

BACKGROUND

This study describes trends in social inequities in first dose measles-mumps-rubella (MMR1) vaccination coverage in Western Australia (WA) and New South Wales (NSW). Using probabilistically-linked administrative data for 1.2 million children born between 2002 and 2011, we compared levels and trends in MMR1 vaccination coverage measured at age 24 months by maternal country of birth, Aboriginal status, maternal age at delivery, socio-economic status, and remoteness in two states.

RESULTS

Vaccination coverage was 3-4% points lower among children of mothers who gave birth before the age of 20 years, mothers born overseas, mothers with an Aboriginal background, and parents with a low socio-economic status compared to children that did not belong to these social groups. In both states, between 2007 and 2011 there was a decline of 2.1% points in MMR1 vaccination coverage for children whose mothers were born overseas. In 2011, WA had lower coverage among the Aboriginal population (89.5%) and children of young mothers (89.3%) compared to NSW (92.2 and 92.1% respectively).

CONCLUSION

Despite overall high coverage of MMR1 vaccination, coverage inequalities increased especially for children of mothers born overseas. Strategic immunisation plans and policy interventions are important for equitable vaccination levels. Future policy should target children of mothers born overseas and Aboriginal children.

A multiple site community outbreak of COVID-19 in Sydney, Australia

OBJECTIVE

To investigate an outbreak of COVID-19 in Sydney, Australia.

METHODS

Epidemiological linking and analysis of cases of COVID-19 across multiple outbreak sites.

RESULTS

Fifteen cases of COVID-19 and 41 contacts were identified and linked in a cluster that included one workplace and five households. The mean incubation period in the cases ranged from 4.6 to 6.4 days, while the median incubation period was shorter, ranging from 3 to 5 days. The overall range of incubation periods was 2 to 12 days. Differential attack rates were found within households (86% adults vs. 9% children) and workplace (32%) settings. Conclusions and implications for public health: Our investigation links cases between multiple households and a workplace. When exploring these links using a rapid workplace assessment, real-time cluster data along with objective measurements of exposure, such as with the Australian Government COVIDSafe app, may have allowed these links to be identified more readily and potentially reduced further spread of COVID-19. We found age as a factor for infection, with children being less likely to both acquire SARS-CoV-2 infection and to develop symptoms. This finding aids in our understanding of how the virus affects children and cautiously supports face-to-face classroom teaching.

Examining the use of antiviral prophylaxis for influenza outbreaks in residential aged care facilities in NSW, Australia

BACKGROUND

Influenza attack rates in closed population settings, such as residential aged care facilities (RACFs), can be more than 50% during annual epidemics. Uncertainty about the effectiveness of neuraminidase inhibitors (NAIs) as prophylaxis for influenza outbreaks has led to variations in their use in RACFs in New South Wales (NSW), Australia.

OBJECTIVES

To examine the use of prophylactic NAIs by NSW RACFs for residents during influenza outbreaks in the 2015 influenza season.

METHODS

A prospective cohort study of influenza outbreaks reported to NSW Public Health Units from 1 June 2015 - 31 October 2015.

RESULTS

Eighty-eight RACFs reported influenza outbreaks; 86 were included in the study. Fifty-two RACFs used prophylactic NAIs; 34 did not. The median time to start NAI prophylaxis from the onset date of the first case was 8.5 days (range 2-23). The average proportion of residents within a facility that received prophylaxis was 51%percnt; (range 0.7-95).

CONCLUSION

Variations in the use of prophylactic NAIs exist across RACFs. Earlier initiation of NAI prophylaxis, improved resident coverage where appropriate and other practice changes are recommended for the management of influenza outbreaks in RACFs.

Epidemiology of lymphogranuloma venereum in New South Wales, 2006-2015

Aim

To describe the epidemiology of lymphogranuloma venereum (LGV) in New South Wales (NSW) from 2006 to 2015.

Methods

LGV notification data between 2006 and 2015 from New South Wales were analysed to describe time trends in counts and rates by gender, age group and area of residence, as well as anatomical sites of infection. A positivity ratio was calculated using the number of LGV notifications per 100 anorectal chlamydia notifications per year. Data linkage was used to ascertain the proportion of LGV cases that were co-infected with HIV.

Results

There were 208 notifications of LGV in NSW from 2006 to 2015; all were among men, with a median age of 42 years, and half were residents of inner-city Sydney. Annual notifications peaked at 57 (1.6 per 100,000 males) in 2010, declined to 16 (0.4 per 100,000 males) in 2014, and then increased to 34 (0.9 per 100,000 males) in 2015. Just under half (47.4%) of LGV cases were determined to be co-infected with HIV.

Conclusion

The number of LGV notifications each year has not returned to the low levels seen prior to the peak in 2010. Continued public health surveillance is important for the management and control of LGV.

Infant, maternal and demographic predictors of delayed vaccination: A population-based cohort study

BACKGROUND

Receiving vaccines at or close to their due date (vaccination timeliness) is a now key measure of program performance. However, studies comprehensively examining predictors of delayed infant vaccination are lacking. We aimed to identify predictors of short and longer-term delays in diphtheria-tetanus-pertussis (DTP) vaccination by dose number and ethnicity.

METHODS

Perinatal, notification, death and immunisation databases were linked for 1.3 million births in 2000-11 from two Australian states (Western Australia and New South Wales), with follow-up data until 2013. Ordinal logistic regression was used to estimate adjusted relative risks (RR) by degree of delay. Separate models were constructed for each vaccine dose and for Aboriginal and non-Aboriginal children.

RESULTS

Each dose-specific cohort included at least 49,000 Aboriginal and 1.1 million non-Aboriginal children. Delayed receipt was more common among Aboriginal than non-Aboriginal children (eg for the first dose of DTP [DTP1] 19.4 v 8.1%). Risk factors for delayed vaccination were strongest for DTP1, and delayed receipt of DTP1 was a key driver of subsequent delays; every week DTP1 was delayed was associated with a 1.6 to 2-fold increased risk of delayed DTP2 receipt. For DTP1, ≥3 previous pregnancies (the only factor more strongly associated with longer than shorter delays; RR ≥5 compared to no previous pregnancies), and children born to mothers <20 years of age (RR ≥2 compared to ≥35 years) were at highest risk of delay. Other independent predictors were prematurity, maternal smoking during pregnancy, and being born in Western Australia (if Aboriginal) or another country in the Oceania region.

CONCLUSION

The sub-populations at risk for delayed vaccination we have identified are likely generalisable to other high-income settings. Measures to improve their dose 1 timeliness, particularly for children with older siblings, are likely to have significant flow-on benefits for timeliness of later doses.

Rotavirus Epidemiology and Monovalent Rotavirus Vaccine Effectiveness in Australia: 2010-2017

BACKGROUND

Rotavirus vaccine has been funded for infants under the Australian National Immunisation Program since 2007, with Rotarix vaccine used in New South Wales, Australia, from that time. In 2017, New South Wales experienced a large outbreak of rotavirus gastroenteritis. We examined epidemiology, genotypic profiles, and vaccine effectiveness (VE) among cases.

METHODS

Laboratory-confirmed cases of rotavirus notified in New South Wales between January 1, 2010 and December 31, 2017 were analyzed. VE was estimated in children via a case-control analysis. Specimens from a sample of hospitalized case patients were genotyped and analyzed.

RESULTS

In 2017, 2319 rotavirus cases were reported, representing a 3.1-fold increase on the 2016 notification rate. The highest rate was among children aged <2 years. For notified cases in 2017, 2-dose VE estimates were 88.4%, 83.7%, and 78.7% in those aged 6 to 11 months, 1 to 3 years, and 4 to 9 years, respectively. VE was significantly reduced from 89.5% within 1 year of vaccination to 77.0% at 5 to 10 years postvaccination. Equinelike G3P[8] (48%) and G8P[8] (23%) were identified as the most common genotypes in case patients aged ≥6 months.

CONCLUSIONS

Rotarix is highly effective at preventing laboratory-confirmed rotavirus in Australia, especially in infants aged 6 to 11 months. Reduced VE in older age groups and over time suggests waning protection, possibly related to the absence of subclinical immune boosting from continuously circulating virus. G8 genotypes have not been common in Australia, and their emergence, along with equinelike G3P[8], may be related to vaccine-induced selective pressure; however, further strain-specific VE studies are needed.

Investigation and response to an outbreak of leptospirosis among raspberry workers in Australia, 2018

BACKGROUND

In 2018, an outbreak of leptospirosis was identified among raspberry workers from a mixed-berry farm in New South Wales, Australia. Initial testing had not revealed a cause, but eventually leptospirosis was detected via polymerase chain reaction (PCR). Further serological testing detected Leptospira borgpetersenii serovar Arborea, of which rodents are the predominant reservoir. Leptospirosis is rare in Australia, with outbreaks usually related to flooding. We conducted an investigation to identify risk factors for infection, to inform control measures.

METHODS

Cases were detected through laboratory notifications, hospital-based syndromic surveillance, awareness-raising among farm employees and clinician alerts. Confirmed cases had a four-fold rise in antibody titre or single titre ≥400 on microscopic agglutination test, and a positive IgM. Probable cases had a positive Leptospira PCR or IgM, and possible cases had a clinically compatible illness. We conducted a case-control study among raspberry workers on the farm and compared reported exposures between cases and seronegative controls. We assessed environmental risks on-site and tested rodents for leptospirosis.

RESULTS

We identified 84 cases over a 5-month period (50 confirmed, 19 probable and 15 possible). Compared with controls, cases were less likely to wear gloves and more recently employed. Cases also more commonly reported always having scratched hands, likely from the thorns on raspberry plants. We observed evidence of rodent activity around raspberry plants and three of thirteen trapped mice tested positive for Leptospira Arborea. Control measures included enhanced glove use, doxycycline prophylaxis and rodent control.

CONCLUSIONS

This is the largest known outbreak of leptospirosis in Australia. Workers were likely exposed through scratches inflicted during harvesting, which became contaminated with environmental leptospires from mice. Leptospirosis should be considered an occupational risk for raspberry workers, requiring protective measures. Chemoprophylaxis may assist in controlling outbreaks. PCR assists in the early diagnosis and detection of leptospirosis and should be included in surveillance case definitions.

Effectiveness of Acellular Pertussis Vaccine in Older Adults: Nested Matched Case-control Study

Background

Despite recommendations that older adults receive acellular pertussis vaccines, data on direct effectiveness in adults aged over 50 years are sparse.

Methods

A case-control study nested within an adult cohort. Cases were identified from linked pertussis notifications and each matched to 3 controls on age, sex, and cohort recruitment date. Cases and controls were invited to complete a questionnaire, with verification of vaccination status by their primary care provider. Vaccine effectiveness (VE) was estimated by conditional logistic regression, with adjustment for reported contact with children and area of residence.

Results

Of 1112 notified cases in the cohort, we had complete data for 333 cases and 506 controls. Among 172 PCR-diagnosed cases (mean age, 61 years), 11.2% versus 19.5% of controls had provider-verified pertussis vaccination, on average, 3.2 years earlier. Adjusted VE against PCR-diagnosed pertussis was 52% (95% CI, 15–73%), nonsignificantly higher if vaccinated within 2 years (63%; −5–87%). Adjusted VE was similar in adults born before 1950, presumed primed by natural infection (51%; −8–77%) versus those born 1950 or later who may have received whole-cell pertussis vaccine (53%; −11–80%) (P-heterogeneity = 0.9). Among 156 cases identified by single-point serology, adjusted VE was −55% (−177–13%).

Conclusions

We found modest protection against PCR-confirmed pertussis among older adults (mean age, 61 years; range, 46–81 years) within 5 years after acellular vaccine. The most likely explanation for the markedly divergent VE estimate from cases identified by single-titer serology is misclassification arising from limited diagnostic specificity in our setting.

Children overdue for immunisation: a question of coverage or reporting? An audit of the Australian Immunisation Register

OBJECTIVE

Vaccinations in Australia are reportable to the Australian Immunisation Register (AIR). Following major immunisation policy initiatives, the New South Wales (NSW) Public Health Network undertook an audit to estimate true immunisation coverage of NSW children at one year of age, and explore reasons associated with under-reporting.

METHODS

Cross-sectional survey examining AIR immunisation records of a stratified random sample of 491 NSW children aged 12≤15 months at 30 September 2017 who were >30 days overdue for immunisation. Survey data were analysed using population weights.

RESULTS

Estimated true coverage of fully vaccinated one-year-old children in NSW is 96.2% (CI:95.9-96.4), 2.1% higher than AIR reported coverage of 94.1%. Of the children reported as overdue on AIR, 34.9% (CI:30.9-38.9) were actually fully vaccinated. No significant association was found between under-reporting and socioeconomic status, rurality or reported local coverage level. Data errors in AIR uploading (at provider level) and duplicate records contributed to incorrect AIR coverage recording.

CONCLUSIONS

Despite incentives to record childhood vaccinations on AIR, under-reporting continues to be an important contributor to underestimation of true coverage in NSW. Implications for public health: More reliable transmission of encounters to AIR at provider level and removal of duplicates would improve accuracy of reported coverage.

A review of listeriosis notifications and co-existing conditions in New South Wales, 2010-2015

AIM

To describe the distribution of known risk factors for listeria infection, including co-existing conditions, among listeriosis notifications in NSW between 2010 and 2015.

METHODS

Data from all notifications of invasive listeriosis in NSW between 01 January 2010 and 31 December 2015 were extracted from the NSW Notifiable Conditions Information Management System (NCIMS). OzFoodNet Listeria Case Questionnaires for each notification were reviewed. Descriptive analyses of notification data were undertaken.

RESULTS

Between 2010 and 2015, there were 158 listeriosis notifications in NSW with an average of 26.3 notifications a year. Persons over 65 years represented 71.5% of all notifications. A total of 4.4% notifications were among pregnant women, while 79.1% and 64.6% were among persons with a condition and on treatment, respectively, known to supress the immune response or increase the risk of infection. Specifically, cancer patients and persons on cancer treatment (chemotherapy, radiotherapy) represented 31.0% and 13.9%, respectively, of all listeriosis notifications. Information on foods to avoid in preventing listeria from a healthcare worker prior to infection was received by 7.2% of notifications with a known risk condition and 5.9% of notifications on medication; 41.6% and 46.1% respectively had visited a hospital in the four weeks prior to notification.

CONCLUSIONS

The prevalence of known risk factors for listeriosis among notified cases remains significant in NSW. Improved risk communication for this population, starting with information from healthcare professionals, may be beneficial in reducing the burden of listeriosis in known vulnerable groups who have regular contact with the health system.

Identifying vulnerable population groups: On-time infant vaccination coverage in Australia

IntroductionImmunisation coverage is a good measure of immunisation program effectiveness. Coverage of the 3-dose infant schedule in Australia assessed at age 12 months is >90%. Timeliness is an important goal for population immunity, but on-time coverage of the 2-4-6 month schedule and coverage in specific populations is rarely reported. Objectives and ApproachWe conducted a retrospective population-based cohort study of 1.9 million Australian births, 1996-2012 (approximately 42% of Australia’s population). Individual data from state-held birth and perinatal records were combined with Commonwealth-held immunisation and death records, through probabilistic linkage. We assessed on-time coverage across 13 demographic and perinatal characteristics of diphtheria-tetanus-pertussis vaccines (DTP) defined as vaccination 14 days prior to the scheduled due date, to 30 days afterwards. ResultsOn-time DTP vaccination coverage in non-Aboriginal infants was 88.1% for the 2-month dose, 82.0% for 4-month dose, and 76.7% for 6-month dose; 3-dose coverage was 91.3% when assessed at 12 months. On-time DTP coverage for Aboriginal infants was 77.0%, 66.5%, and 61.0%; 3-dose coverage at 12 months was 79.3%. Appreciable differences in on-time coverage were observed across population subgroups. On-time coverage in non-Aboriginal infants born to mothers with ≥3 previous pregnancies was 62.5% for the 6-month dose (47.9% for Aboriginal infants); up to 23.5% lower than for first-borns. Infants born to mothers who smoked during pregnancy had coverage 8.7-10.3% lower than infants born to non-smoking mothers for the 4- and 6-month dose. A linear relationship was apparent with increasing socio-economic disadvantage and decreasing on-time coverage. Conclusion/ImplicationsOn-time vaccination coverage of the 2-4-6 month schedule is only 50-60% across specific population subgroups representing a significant avoidable public health risk. Australian Aboriginal infants, multiparous mothers, and those who are socio-economically disadvantaged are key groups most likely to benefit from targeted programs addressing vaccine timeliness.

Assessment of on-time vaccination coverage in population subgroups: A record linkage cohort study

Reported infant vaccination coverage at age 12 months in Australia is >90%. On-time coverage of the 2-4-6 month schedule and coverage in specific populations is rarely reported. We conducted a population-based cohort study of 1.9 million Australian births, 1996-2012, combining individual birth and perinatal records with immunisation records through probabilistic linkage. We assessed on-time coverage across 13 demographic and perinatal characteristics of diphtheria-tetanus-pertussis vaccines (DTP) defined as vaccination 14 days prior to the scheduled due date, to 30 days afterwards. On-time DTP vaccination coverage in non-Aboriginal infants was 88.1% for the 2-month dose, 82.0% for 4-month dose, and 76.7% for 6-month dose; 3-dose coverage was 91.3% when assessed at 12 months. On-time DTP coverage for Aboriginal infants was 77.0%, 66.5%, and 61.0% for the 2-4-6 month dose; 3-dose coverage at 12 months was 79.3%. Appreciable differences in on-time coverage were observed across population subgroups. On-time coverage in non-Aboriginal infants born to mothers with ≥3 previous pregnancies was 62.5% for the 6-month dose (47.9% for Aboriginal infants); up to 23.5 percentage points lower than for first-borns. Infants born to mothers who smoked during pregnancy had coverage 8.7-10.3 percentage points lower than infants born to non-smoking mothers for the 4- and 6-month dose. A linear relationship was apparent between increasing socio-economic disadvantage and decreasing on-time coverage. On-time coverage of the 2-4-6 month schedule is only 50-60% across specific population subgroups representing a significant avoidable public health risk. Aboriginal infants, multiparous mothers, and those who are socio-economically disadvantaged are key groups most likely to benefit from targeted programs addressing vaccine timeliness.

Effectiveness of maternal pertussis vaccination in preventing infection and disease in infants: The NSW Public Health Network case-control study

BACKGROUND

Infants are at the highest risk of severe complications - including death - as a result of pertussis infection. Controlling pertussis in this group has been challenging, particularly in those too young to be vaccinated. Following revised national recommendations in March 2015, the state of New South Wales, Australia, introduced a funded maternal vaccination campaign at 28 - 32 weeks of gestation using a 3-component tetanus-diphtheria-acellular pertussis vaccine (dTpa; Boostrix, GSK). This study aimed to assess the effectiveness of maternal vaccination and add to the growing body of evidence for this strategy.

METHODS

A 1:1 matched case-control study was conducted between 16 August 2015 and 17 August 2016. Cases were laboratory or doctor notified, laboratory confirmed (nucleic acid testing or culture) and aged <6 months at onset. Each control infant was randomly selected from public hospital births in the same geographical area in the period up to 3 days before and after the case's birthdate. Odds ratios (OR) were calculated using conditional logistic regression. Vaccine effectiveness (VE) was calculated as 1 - OR.

FINDINGS

In total, 117 cases and 117 controls were recruited. The overall VE estimate was non-significantly protective for infants <6 months old (VE 39%, 95% CI -12 to 66%). Higher VE was observed for infants <3 months old (VE 69%, 95% CI 13-89%) and against hospitalisation (VE 94%, 95% CI 59-99%).

INTERPRETATION

Maternal pertussis vaccination with a 3-component acellular vaccine was found to be highly effective at preventing severe disease in infants, but was less effective at preventing disease which did not require hospitalisation. The overall VE reported in this study was lower than in prior studies and suggests that maternal vaccination, while an effective strategy at preventing severe pertussis, is less effective at protecting against infection or mild disease.

Probabilistic linkage of national immunisation and state-based health records for a cohort of 1.9 million births to evaluate Australia's childhood immunisation program

Introduction

Several countries have developed national immunisation registers, but only the Nordic countries have linked their registers to other health data in order to comprehensively evaluate the `real world' effectiveness of vaccines. Nordic countries can link datasets deterministically using the national person identifier, but most countries, including Australia, don't have such an identifier to enable this type of linkage.

Objectives

To describe the process for assembling a linked study cohort that will enable the conduct of population-based studies related to immunisation and immunisation policy.

Methods

National death and immunisation databases along with state health data (notifications of vaccine preventable diseases, perinatal data, hospital admissions and emergency department presentations) up until December 2013 were probabilistically linked (using demographic details) for children born between 1996 and 2012 in two states: Western Australia and New South Wales (42% of Australia's population, combined).

Results

After exclusions there were 1.95 million children in the study cohort (live born children with both a birth and perinatal record which represents 97.5% of all live births in the state perinatal data collections - our source population) and 18.0 million person years of follow up (mean: 9.2 years per child). The characteristics of children in the cohort were generally similar to those only included in state perinatal databases and outcome measures were in keeping with expected figures from unlinked data sources. However, the lack of a dynamic national population register meant immigrants could not be included.

Conclusions

We have been able to develop a similarly comprehensive system to the Nordic countries based on probabilistic linkage methods. Our experience should provide encouragement to other countries with national immunisation registers looking to establish similar systems.

An outbreak of psittacosis at a veterinary school demonstrating a novel source of infection

In November 2014, New South Wales Health was notified of a cluster of respiratory illness in a veterinary school. Active case finding identified another case at a local equine stud. All cases had exposure to the equine fetal membranes of Mare A. This tissue subsequently tested positive for Chlamydia psittaci using quantitative real-time polymerase chain reaction. We conducted a cohort study of the university and stud farm staff to determine risk factors for disease. Nine people were exposed to the fetal membranes of Mare A. Of these, five cases of psittacosis were identified. Two required hospital admission. Contact with birds was not associated with illness (RR = 0.5, 95% CI = 0.09-2.73). People who had direct contact with the abnormal fetal membranes were more likely to develop disease (RR = 11.77, 95% CI = 1.02-∞). The emergence of an association between horse exposure and C. psittaci infection has important implications for the prevention and control of psittacosis. Article summary line: Investigation of an outbreak of psittacosis in a rural veterinary school demonstrates novel source of infection for psittacosis through exposure to abnormal equine fetal membranes.

First reported outbreak of locally acquired hepatitis E virus infection in Australia

OBJECTIVE

To determine the source and extent of a locally acquired hepatitis E virus (HEV) infection outbreak.

DESIGN, SETTING AND PARTICIPANTS

A cluster of notified cases of HEV infection linked to a single restaurant (X) was identified in May 2014. People with laboratory-confirmed HEV infection in New South Wales between January 2013 and December 2014 were interviewed about potential risk factors for HEV infection. Co-diners at restaurant X and patients with suspected but unexplained viral hepatitis were retrospectively tested. Foods eaten by the infected persons were compared with those of seronegative co-diners. HEV RNA detected in sera from infected persons was sequenced and genotyped. Implicated foods were traced back to their sources.

MAIN OUTCOME MEASURES

Potential sources of infection, including overseas travel and foods eaten, and origin of implicated food products.

RESULTS

In 55 serologically confirmed cases of HEV infection, 24 people had not travelled overseas during their incubation periods. Of the 24, 17 reported having eaten at restaurant X, 15 of whom could be interviewed. All reported consuming pork liver pâté, compared with only four of seven uninfected co-diners (P < 0.05). The other seven people with locally acquired infections each reported consuming a pork product during their incubation periods. HEV RNA was detected in 16 of the 24 cases; all were of genotype 3. Sequencing indicated greater than 99% homology among restaurant X isolates. HEV RNA was isolated from pork sausages from a batch implicated in one of the locally acquired infections not linked with restaurant X. The pork livers used for pâté preparation by restaurant X were traced to a single Australian farm.

CONCLUSIONS

This is the first reported HEV outbreak in Australia. HEV should be considered in patients presenting with a compatible illness, even without a history of overseas travel. Pork products should be thoroughly cooked before consumption.

An evaluation of the use of short message service during an avian influenza outbreak on a poultry farm in Young

In 2013 an avian influenza outbreak occurred in a large poultry farm in Young (approximately 2 hours north-west of Canberra.) The responsible strain was H7N2, which is highly pathogenic and can affect humans. Daily surveillance was required for those individuals who were possibly exposed. This was conducted through the use of daily message through the short message service (SMS). A total of 55 people were identified as having had high risk exposure and requiring monitoring during the surveillance period from 16 to 25 October 2013. A SMS message was sent daily to each contact within 2 groups. (Group 1 were contacts who agreed to take Tamiflu prophylaxis, and Group 2 were contacts who were under surveillance but declined Tamiflu prophylaxis). The average daily response rate for SMS was 66% (median 75%) over a 9 day period. Of those who nominated to receive the daily SMS 98% confirmed they'd received the SMS and it reminded them to take their Tamiflu medication. The public health unit (PHU) team found the use of SMS to be less time consuming than conducting telephone follow-up interviews. The PHU team believed that the use of the technology decreased the likelihood of additional staff being required to assist in the outbreak. Utilising SMS was a new initiative for the PHU and staff found it overall easy to use. These findings confirm there can be significant benefits to using SMS during a large surveillance activity. The application of SMS during this outbreak was estimated at 2.5 times more cost effective that telephone follow-ups and would substantially reduce staffing costs further in the event of a very large outbreak.

Parechovirus Genotype 3 Outbreak among Infants, New South Wales, Australia, 2013-2014

Syndromic surveillance was useful for outbreak monitoring, and public health response helped reduce hospitalization times.

From October 2013 through February 2014, human parechovirus genotype 3 infection was identified in 183 infants in New South Wales, Australia. Of those infants, 57% were male and 95% required hospitalization. Common signs and symptoms were fever >38°C (86%), irritability (80%), tachycardia (68%), and rash (62%). Compared with affected infants in the Northern Hemisphere, infants in New South Wales were slightly older, both sexes were affected more equally, and rash occurred with considerably higher frequency. The New South Wales syndromic surveillance system, which uses near real-time emergency department and ambulance data, was useful for monitoring the outbreak. An alert distributed to clinicians reduced unnecessary hospitalization for patients with suspected sepsis.

Outbreak-related Hendra virus infection in a NSW pet dog

Hendra virus (HeV) infection is a zoonosis of importance in Australia. An outbreak of HeV occurred on the mid-north coast region of New South Wales (NSW) in June and July 2013. Four unvaccinated horses on four separate properties were confirmed to have HeV infection. A pet dog that had close contact with one of the horses was also confirmed to be infected with HeV. This paper documents the response to the canine infection and the resulting change to the public health management of HeV infection.

Description of the Western Sydney and Nepean Blue Mountains local health districts' influenza prevention programme

BACKGROUND

Influenza is a major cause of morbidity and mortality. In 2011, influenza vaccination was provided free for people at greatest risk of severe disease: people aged 65 years and over, Aboriginal Australians 15 years and older, pregnant women, and individuals aged 6 months and over who suffered chronic medical conditions.

AIMS

To evaluate the Western Sydney and Nepean Blue Mountains Local Health District Influenza Prevention Program and to identify some of the enablers and barriers to vaccination in the hospital outpatient setting.

METHODS

Western Sydney and Nepean Blue Mountains local health districts' influenza prevention programme provided influenza vaccine in hospital outpatient settings between 21 March 2011 and 30 June 2011. Accredited nurse immunisers vaccinated 2824 individuals and recorded their primary reason for vaccination. Nurse immunisers were interviewed to identify barriers and enablers to influenza immunisation uptake.

RESULTS

Two thousand, eight hundred and twenty-four doses of influenza vaccine were administered to people at high risk of influenza in four hospitals in the region: two tertiary facilities and two district hospitals. The primary indication for vaccination was chronic disease in 50% and pregnancy in 37%. Estimated direct cost of the programme was $19 per dose.

CONCLUSIONS

A hospital-based influenza vaccination programme can be an effective way to improve influenza vaccination rates among specific population groups at high risk of severe disease with influenza, particularly pregnant women and those younger than 65 years with a chronic medical condition.

Impacts of a measles outbreak in Western Sydney on public health resources

During February and March 2011, an outbreak of 26 confirmed cases of measles was reported to the Parramatta Public Health Unit (PHU) in western Sydney. This paper describes the impact of the outbreak on PHU resources. A retrospective review of information obtained from case notification forms and associated contact tracing records was carried out for each of the confirmed cases. Seven cases (27%) required hospital admission for more than 1 day and 10 (38%) cases required management within a hospital emergency department. There were no cases of encephalitis or death. The number of contacts was determined for each case as well as the number who required post-exposure prophylaxis. In total, 1,395 contacts were identified in this outbreak. Of these, 79 (5.7%) required normal human immunoglobulin and 90 (6.5%) were recommended to receive the measles-mumps-rubella vaccine. A case study detailing the PHU costs associated with the contact management of a hospitalised measles case with 75 identified contacts is also included and the estimated total cost to the PHU of containing this particular case of measles was A$2,433, with staff time comprising the major cost component. Considerable effort and resources are required to manage measles outbreaks. The total cost of this outbreak to the PHU alone is likely to have exceeded A$48,000.

An outbreak of staphylococcal food poisoning in a commercially catered buffet

Staphylococcal food poisoning is a common cause of foodborne illness. In Australia, since 2000, approximately 30% of foodborne Staphylococcus aureus outbreaks reported to OzFoodNet have been associated with foods prepared by commercial caterers. We conducted a retrospective cohort analysis of an outbreak of gastrointestinal illness among participants of an elite sporting event during which 22 individuals became ill after eating a commercially catered buffet dinner in June 2012. All recalled eating fried rice which had been intended for lunch service earlier that day and 20 of the 22 reported eating chicken stir-fry. Though no food samples were available for analysis, laboratory analysis conducted on four faecal specimens resulted in S. aureus being cultured from one specimen and S. aureus enterotoxin detected in another. The known epidemiology of staphylococcal food poisoning suggests a food contaminated by an infected food handler which was subject to temperature abuse may have caused the outbreak. As S. aureus foodborne outbreaks are often underreported, this investigation is a valuable contribution to the evidence-base and understanding of foodborne illness due to S. aureus and staphylococcal enterotoxin.

Respiratory health before and after the opening of a road traffic tunnel: a planned evaluation

Objective

The construction of a new road tunnel in Sydney, Australia, and concomitant reduction in traffic on a major road presented the opportunity to study the effects of this traffic intervention on respiratory health.

Methods

We made measurements in a cohort of residents in the year before the tunnel opened (2006) and in each of two years afterwards (2007–2008). Cohort members resided in one of four exposure zones, including a control zone. Each year, a respiratory questionnaire was administered (n = 2,978) and a panel sub-cohort (n = 380) performed spirometry once and recorded peak expiratory flow and symptoms twice daily for nine weeks.

Results

There was no consistent evidence of improvement in respiratory health in residents living along the bypassed main road, despite a reduction in traffic from 90,000 to 45,000 vpd. Residents living near tunnel feeder roads reported more upper respiratory symptoms in the survey but not in the panel sub-cohort. Residents living around the tunnel ventilation stack reported more upper and lower respiratory symptoms and had lower spirometric volumes after the tunnel opened. Air pollutant levels measured near the stack did not increase over the study period.

Conclusion

The finding of adverse health effects among residents living around the stack is unexpected and difficult to explain, but might be due to unmeasured pollutants or risk factors or an unrecognized pollutant source nearby. The lack of improvement in respiratory health among people living along the bypassed main road probably reflects a minimal change in exposure due to distance of residence from the road.