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Objectives The aim of the study was to assess whether subpopulations with sufficiently high HIV incidences for HIV prevention trials can be identified in low HIV incidence settings such as Australia. Methods In a community-based cohort study of HIV-negative homosexually active men in Sydney, Australia, potential risk factors associated with an annual HIV incidence of ≥2 per 100 person-years (PY) were identified. A stepwise procedure ranked these factors according to HIV incidence, to create a 'highincidence' subgroup of participants. Willingness to participate in HIV prevention trials was assessed. Results Although the incidence in the cohort overall was only 0.78 per 100 PY, nine risk variables were associated with an HIV incidence of 2 per 100 PY or greater. Stepwise inclusion of these variables revealed a 'high-incidence' subgroup of men representing 24% of the total follow-up time with a combined HIV incidence of 2.71 per 100 PY, who reported at least one of three risk factors in the past 6 months. These men were more willing than others to participate in vaccine and antiretroviral therapy HIV prevention trials. Conclusions These findings demonstrate that it is possible to identify high HIV incidence subpopulations in lowincidence settings such as Australia, and these men are of above average willingness to participate in HIV prevention trials. [ABSTRACT FROM AUTHOR]

This paper reports on the breaking of agreements between regular partners among HIV-negative gay men in Sydney. Data were from the 1333 men completing face-to-face interviews through December 2003 for the Health in Men (HIM) open cohort of HIV-negative gay men in Sydney. 822 men had a primary regular partner during the six month period before their 2003 interview. Most of these men had entered into agreements with their partners about sex either with each other or with other partners (87.2%). They most commonly agreed not to use condoms with each other (50.6%). Regarding casual sex, they most commonly agreed to always use condoms (34.2%) or to have no sex with men outside their relationships (28.6%). 48.8% reported some discomfort discussing with their partner their sex outside the relationship. Among those with agreements with their partners, 27.7% reported ever breaking those agreements. Those who found it more difficult to discuss issues of HIV serostatus and sexuality were more likely to report having broken their agreements ( p <.001; p =.021 at one-year follow-up) and were more likely to have engaged in unprotected anal intercourse with casual partners ( p <.001). A third of those men who broke their agreements did not inform their partner. A substantial proportion of gay men with agreements with their regular partners report some discomfort discussing sexuality and HIV serostatus with their partners. Difficulty discussing these issues may place these men at increased risk of breaking their agreements and may place both themselves and their partners at increased risk of infection. [ABSTRACT FROM AUTHOR]

This paper describes the prevalence of, and risk factors for, exposure to syphilis in a random sample of male and female prisoners. We found that only 2% of male and 1% of female prison inmates in New South Wales (NSW) had confirmed evidence of untreated syphilis, and none appeared to be in an infectious phase. In the multivariate analysis, indigenous ethnicity remained the most potent predictor for confirmed syphilis (either past or present). There was some evidence to suggest that syphilis among indigenous prisoners may be associated with limited access to health services outside prison. The epidemiology of syphilis reflects that of the general community suggesting that prisons could be used as sentinel sites to help evaluate the effectiveness of STD prevention and control strategies. [ABSTRACT FROM AUTHOR]

Our objectives were to determine the prevalence of, and risk factors for, herpes simplex virus type 2 (HSV-2) antibodies in male and female prisoners. A cross-sectional random sample was used consisting of 789 prisoners (657 males and 132 females) from 27 correctional centres across New South Wales (NSW), stratified by sex, age and Aboriginality. Participants were questioned about demographics and behavioural risk factors and were screened for serum antibody to HSV-2. The overall prevalence of HSV-2 antibodies was higher in females (58%) than males (21%), and in Aborigines (34%) compared with non-Aborigines (24%). HSV-2 prevalence increased with the number of sexual partners. Few prisoners (1%) reported a previous diagnosis of genital herpes. Independent risk factors for the presence of HSV-2 antibodies were increasing age and Aboriginality for men, and higher reported number of lifetime sexual partners and the presence of hepatitis C antibodies for women. HSV-2 infection is common in prison inmates. There is a need to incorporate information about STDs, including HSV-2, into education programmes for inmates. [ABSTRACT FROM AUTHOR]

A case control analysis within an ongoing cohort study was used to examine differences between seroconverters and men who remained HIV-negative. The cases were interviewed within one to 13 months prior to their seroconversion. Their responses to a structured questionnaire were compared with those of HIV-negative controls drawn from the same time period and from the same longitudinal study, Sydney Men and Sexual Health. Data collected from both cases and controls included: demographic and contextual variables, knowledge of HIV transmission, sexual practices, drug and alcohol use and attitudinal factors. The aim was to compare the sexual behaviours, and the social and cultural contexts of such behaviours, of men prior to their HIV seroconversion with men who did not seroconvert. Twenty-three men had seroconverted within the cohort. Cases were identified by a positive HIV antibody test or self-report of positive HIV status following a previous negative HIV test. Three-hundred-and-sixty-nine controls were selected on the basis of being HIV negative at interview in 1994, and having at least one subsequent medically-confirmed negative HIV antibody test. Univariate predictors of seroconversion were: being in a regular relationship with a known HIV-positive partner, drug use, and engaging in a range of anal and esoteric sexual practices. Practices commonly used to enhance sexual pleasure, such as group sex, watching and being watched having sex, the use of sex toys and dressing up/fantasy, were engaged in more frequently by seroconverters. Engaging in these esoteric sexual practices was highly correlated with drug use, involvement in the gay community and engagement in a wide range of anal practices. In the multivariate analysis independent predictors of seroconversion were: younger age; being in a regular relationship with a known HIV-positive partner; believing withdrawal to be safe with regard to HIV transmission; and range of esoteric practices. These results indicate the importance of the social and cultural contexts of particular sexual practices and consequent HIV transmission. Sexually adventurous men may be at increased risk for HIV because they seek sex within particular sexual sub-cultures. [ABSTRACT FROM AUTHOR]

Introduction: The Department of Health in New South Wales, Australia, expanded public health surveillance for the 2003 Rugby World Cup and for its ongoing counterterrorism response. Cup games were played in and around the Sydney region. Objectives: This study explains the development of an automated, near real-time, syndromic surveillance system in which data are used that are already being collected in emergency department (ED) databases for routine patient administration. Methods: Demographic, triage, physician-assigned provisional diagnosis, and disposition information from 12 of 49 public hospital EDs in the greater Sydney metropolitan area was frequently and automatically transmitted, analyzed, and reported in daily statistical summaries on Intranet websites beginning October 10, 2003. Diagnoses were categorized by syndrome, disease, and injury. Presenting problem and nursing-assessment free text routinely entered by nurses during patient triage were automatically classified into >30 syndrome categories by using automated preprocessing techniques and naïve Bayesian automatic text classification methods. The diagnosis-based categories were used to train the automatic classifier to associate words in the free text with syndrome categories. An adjusted cumulative sum (CUSUM) accumulating day-of-week differences in daily counts was used to assess the statistical significance of disease and injury trends. Public health personnel monitored the reports daily and notified the Rugby World Cup Public Health Committee of unusual trends. Results: During the tournament, October 10-November 22, health trends identified by the system were not sufficient to cause concern among public health personnel but did provide reassurance that the health of the population was not adversely affected. Data collection did not add to the work load of clinical staff in EDs, and surveillance downtime was negligible. Since the games, this now ongoing surveillance system has rapidly identified a community-based epidemic of gastrointestinal illness, an increase in recreational drug misuse, the annual influenza epidemic, and an increase in episodes of acute asthma. Variation by syndrome occurred in the degree of correlation between daily visit counts from automatically classified nurse text and the equivalent diagnosis groups used to train the classifier. Conclusion: During the Rugby World Cup, the surveillance system complemented traditional public health surveillance to provide a comprehensive assessment of health trends in the population. A substantial advantage of the system has been its ongoing sustainability. Physician-assigned diagnoses are more specific than free text for some syndrome and diagnostic categories. However, diagnoses are not available for analysis until at least the end of a patient's ED visit, and they are sometimes incomplete. Free text from patient triage is available for analysis early in an ED visit, and depending on the scope of the text description, multiple text-based syndromes can be automatically assigned to a visit. [ABSTRACT FROM AUTHOR]

Introduction: Exposure to high ambient temperatures and air pollution has been shown to increase the risk of spontaneous preterm birth (sPTB). Less clear are the effects of cold and the joint effects of air pollution and temperature., Methods: Using a Cox proportional hazard regression model, we assessed the risk of independent and combined short-term exposure to ambient daily mean temperature and PM 2.5 associated with sPTB in the last week before delivery on overall sPTB (weeks 23-36) and three subtypes: extremely sPTB, very sPTB, and moderate-to-late sPTB for a birth cohort of 1,318,570 births from Australia (Jan 2001-Dec 2019), while controlling for chronic exposure (i.e., throughout pregnancy except the last week before delivery) to PM 2.5 and temperature. The temperature was modeled as a natural cubic spline, PM 2.5 as a linear term, and the interaction effect was estimated using a multiplicative term. For short-term exposure to temperature hazard ratios reported are relative to the median temperature (18.1°C)., Results: Hazard ratios at low temperature [5th percentile(11.5°C)] were 0.95 (95% CI: 0.90, 1.00), 1.08 (95% CI: 0.84, 1.4), 0.87 (95% CI: 0.71, 1.06), and 1.00 (95% CI: 0.94, 1.06) and greater for high temperature [95th percentile (24.5°C)]: 1.22 (95% CI: 1.16, 1.28), 1.27 (95% CI: 1.03, 1.57), and 1.26 (95% CI: 1.05, 1.5) and 1.05 (1.00, 1.11), respectively, for overall, extremely, very, and moderate-to-late sPTBs. While chronic exposure to PM 2.5 had adverse effects on sPTB, short-term exposure to PM 2.5 appeared to have a negative association with all types of sPTB, with hazard ratios ranging from 0.86 (95th CI: 0.80, 0.94) to 0.98 (95th CI: 0.97, 1.00) per 5 μg/m 3 increase in PM 2.5 ., Discussion: The risk of sPTB was found to increase following acute exposure to hot and cold ambient temperatures. Earlier sPTB subtypes seemed to be the most vulnerable. This study adds to the evidence that short-term exposure to ambient cold and heat and longer term gestational exposure to ambient PM 2.5 are associated with an elevated risk of sPTB., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Singh, Jalaludin, Hajat, Morgan, Meissner, Kaldor, Green and Jegasothy.)

Background: Digital proximity tracing apps were rolled out early in the COVID-19 pandemic in many countries to complement conventional contact tracing. Empirical evidence about their benefits for pandemic response remains scarce. We evaluated the effectiveness and usefulness of COVIDSafe, Australia's national smartphone-based proximity tracing app for COVID-19., Methods: In this prospective study, done in New South Wales (NSW), Australia, we included all individuals in the state who were older than 12 years with confirmed, locally acquired SARS-CoV-2 infection between May 4 and Nov 4, 2020. We used data from the NSW Notifiable Conditions Information Management System, the national COVIDSafe database, and information from case interviews, including information on app usage, the number of app-suggested contacts, and the number of app-suggested contacts determined by public health staff to be actual close contacts. We calculated the positive predictive value and sensitivity of COVIDSafe, its additional contact yield, and the number of averted public exposure events. Semi-structured interviews with public health staff were done to assess the app's perceived usefulness., Findings: There were 619 confirmed COVID-19 cases with more than 25 300 close contacts identified by conventional contact tracing during the study period. COVIDSafe was used by 137 (22%) cases and detected 205 contacts, 79 (39%) of whom met the close contact definition. Its positive predictive value was therefore 39%. 35 (15%) of the 236 close contacts who could have been expected to have been using the app during the study period were identified by the app, making its estimated sensitivity 15%. 79 (0·3%) of the estimated 25 300 contacts in NSW were app-suggested and met the close contact definition. The app detected 17 (<0·1%) additional close contacts who were not identified by conventional contact tracing. COVIDSafe generated a substantial additional perceived workload for public health staff and was not considered useful., Interpretation: The low uptake of the app among cases probably led to a reduced sensitivity estimate in our study, given that only contacts who were using the app could be detected. COVIDSafe was not sufficiently effective to make a meaningful contribution to the COVID-19 response in Australia's most populous state over a 6 month period. We provide an empirical evaluation of this digital contact tracing app that questions the potential benefits of digital contact tracing apps to the public health response to COVID-19. Effectiveness evaluations should be integrated into future implementations of proximity contact tracing systems to justify their investment., Funding: New South Wales Ministry of Health (Australia); National Health and Medical Research Council (Australia)., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background: Financial incentives and audit/feedback are widely used in primary care to influence clinician behaviour and increase quality of care. While observational data suggest a decline in quality when these interventions are stopped, their removal has not been evaluated in a randomised controlled trial (RCT), to our knowledge. This trial aimed to determine whether chlamydia testing in general practice is sustained when financial incentives and/or audit/feedback are removed., Methods and Findings: We undertook a 2 × 2 factorial cluster RCT in 60 general practices in 4 Australian states targeting 49,525 patients aged 16-29 years for annual chlamydia testing. Clinics were recruited between July 2014 and September 2015 and were followed for up to 2 years or until 31 December 2016. Clinics were eligible if they were in the intervention group of a previous cluster RCT where general practitioners (GPs) received financial incentives (AU$5-AU$8) for each chlamydia test and quarterly audit/feedback reports of their chlamydia testing rates. Clinics were randomised into 1 of 4 groups: incentives removed but audit/feedback retained (group A), audit/feedback removed but incentives retained (group B), both removed (group C), or both retained (group D). The primary outcome was the annual chlamydia testing rate among 16- to 29-year-old patients, where the numerator was the number who had at least 1 chlamydia test within 12 months and the denominator was the number who had at least 1 consultation during the same 12 months. We undertook a factorial analysis in which we investigated the effects of removal versus retention of incentives (groups A + C versus groups B + D) and the effects of removal versus retention of audit/feedback (group B + C versus groups A + D) separately. Of 60 clinics, 59 were randomised and 55 (91.7%) provided data (group A: 15 clinics, 11,196 patients; group B: 14, 11,944; group C: 13, 11,566; group D: 13, 14,819). Annual testing decreased from 20.2% to 11.7% (difference -8.8%; 95% CI -10.5% to -7.0%) in clinics with incentives removed and decreased from 20.6% to 14.3% (difference -7.1%; 95% CI -9.6% to -4.7%) where incentives were retained. The adjusted absolute difference in treatment effect was -0.9% (95% CI -3.5% to 1.7%; p = 0.2267). Annual testing decreased from 21.0% to 11.6% (difference -9.5%; 95% CI -11.7% to -7.4%) in clinics where audit/feedback was removed and decreased from 19.9% to 14.5% (difference -6.4%; 95% CI -8.6% to -4.2%) where audit/feedback was retained. The adjusted absolute difference in treatment effect was -2.6% (95% CI -5.4% to -0.1%; p = 0.0336). Study limitations included an unexpected reduction in testing across all groups impacting statistical power, loss of 4 clinics after randomisation, and inclusion of rural clinics only., Conclusions: Audit/feedback is more effective than financial incentives of AU$5-AU$8 per chlamydia test at sustaining GP chlamydia testing practices over time in Australian general practice., Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN12614000595617., Competing Interests: All authors have completed the ICMJE uniform disclosure form. I have read the journal’s policy and the authors have the following competing interests: ML has received research grants to his institution from Gilead Sciences, Janssen-Cilag and ViiV Healthcare; NL is a member of the Editorial Board of PLOS Medicine.

Background: Increasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited., Methods: All cases of COVID-19 diagnosed from January-October 2020 in New South Wales Australia were followed for COVID-19-related hospitalisations, intensive care unit (ICU) admissions and deaths through record linkage. Adjusted hazard ratios (aHR) for severe COVID-19 disease, measured by hospitalisation or death, or very severe COVID-19, measured by ICU admission or death according to age, sex, socioeconomic status and co-morbidities were estimated., Results: Of 4054 confirmed cases, 468 (11.5%) were classified as having severe COVID-19 and 190 (4.7%) as having very severe disease. After adjusting for sex, socioeconomic status and comorbidities, increasing age led to the greatest risk of very severe disease. Compared to those 30-39 years, the aHR for ICU or death from COVID-19 was 4.45 in those 70-79 years; 8.43 in those 80-89 years; 16.19 in those 90+ years. After age, relative risks for very severe disease associated with other factors were more moderate: males vs females aHR 1.40 (95%CI 1.04-1.88); immunosuppressive conditions vs none aHR 2.20 (1.35-3.57); diabetes vs none aHR 1.88 (1.33-2.67); chronic lung disease vs none aHR 1.68 (1.18-2.38); obesity vs not obese aHR 1.52 (1.05-2.21). More comorbidities was associated with significantly greater risk; comparing those with 3+ comorbidities to those with none, aHR 5.34 (3.15-9.04)., Conclusions: In a setting with high COVID-19 case ascertainment and almost complete case follow-up, we found the risk of very severe disease varies by age, sex and presence of comorbidities. This variation should be considered in targeting prevention strategies., (© 2021. The Author(s).)

Objective: To describe hospitalisation rates following COVID-19 infection in NSW., Design, Setting and Participants: Analysis of all confirmed COVID-19 cases diagnosed in NSW from 1 January to 31 May 2020 extracted from the NSW Notifiable Conditions Information Management System and linked to routinely collected hospitalisation data., Outcome Measures: In-patient hospitalisations and hospital service utilisation details., Results: There were 3,101 COVID-19 cases diagnosed between 1 January and 31 May 2020 in NSW: mean age 46.7 years, 50.5% were females. Overall, 12.5% (n = 389) had a record of inpatient hospitalisation, 4.2% (n = 130) were admitted to ICU and 1.9% (n = 58) received ventilation. Among adult cases, hospital and ICU admission rates increased with increasing age: 2.9% of those aged 20-29 years were hospitalised, increasing to 46.6% of those aged 80-89 years; 0.6% of those aged 20-29 years were admitted to ICU, increasing to 11.2% of those aged 70-79 years. The median time from symptoms to hospitalisation was seven days (IQR 4-11). The median time in hospital was nine days (IQR 4-20), and in ICU six days (IQR 2-15); the median time in hospital increased with older age. Almost half (49.4%) of those hospitalised with a diagnostic code had pneumonia/lower respiratory tract infection and another 36.6% had an upper respiratory tract infection or other known COVID-19 symptoms., Conclusion: COVID-19 is a serious infection particularly in older adults. During January to May of 2020, 1 in 8 of those diagnosed in NSW were hospitalised. While this partly reflects the cautious approach to case management in the initial phase of the pandemic, it also demonstrates the large potential impact of COVID-19 on Australian health services and need for continuing mitigation strategies., (© Commonwealth of Australia CC BY-NC-ND.)

Introduction: Australia has recently implemented major changes in cervical cancer prevention policies including introduction of primary human papillomavirus (HPV) screening starting at age 25, and replacement of the quadrivalent HPV vaccine with the nonavalent vaccine in the national school-based program. We assessed the feasibility and utility of conducting HPV testing in residual clinical specimens submitted for routine Chlamydia trachomatis screening, as a means of tracking HPV vaccine program impact among young sexually active women., Methods: De-identified residual specimens from women aged 16-24 years submitted for chlamydia testing were collected from three pathology laboratories in Victoria and New South Wales. Limited demographic information, and chlamydia test results were also collected. Patient identifiers were sent directly from the laboratories to the National HPV Vaccination Program Register, to obtain HPV vaccination histories. Samples underwent HPV genotyping using Seegene Anyplex II HPV 28 assay., Results: Between April and July 2018, 362 residual samples were collected, the majority (60.2%) of which were cervical swabs. Demographic data and vaccination histories were received for 357 (98.6%) women (mean age 21.8, SD 2.0). Overall, 65.6% of women were fully vaccinated, 9.8% partially, and 24.7% unvaccinated. The majority (86.0%) resided in a major city, 35.9% were classified in the upper quintile of socioeconomic advantage and chlamydia positivity was 7.8%.The prevalence of quadrivalent vaccine-targeted types (HPV6/11/16/18) was 2.8% (1.5-5.1%) overall with no differences by vaccination status (p = 0.729). The prevalence of additional nonavalent vaccine-targeted types (HPV31/33/45/52/58) was 19.3% (15.6-23.8%). One or more oncogenic HPV types were detected in 46.8% (95% CI 41.6-52.0%) of women., Conclusions: HPV testing of residual chlamydia specimens provides a simple, feasible method for monitoring circulating genotypes. Applied on a larger scale this method can be utilised to obtain a timely assessment of nonavalent vaccine impact among young women not yet eligible for cervical screening., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: DAM reports travel grants from Seqirus, travel funding and honoraria to her institute from Merck Sharp & Dohme (MSD), outside the submitted work. JMLB, MS and DH are investigators on the Compass trial for which VCS Foundation has received kits and partial funding from Roche. VCS Pathology has also received free test kits from Roche, Seegene, Cepheid, and Becton Dickinson. JMLB, MS and SMG were investigators on a cervical cancer typing study with laboratory testing funded by Seqirus more than three years ago. JMLB and SMG were investigators on a recurrent respiratory papillomatosis surveillance study partially funded by an investigator initiated grant from MSD more than three years ago. SMG has received grants to her institution from Merck and GSK (GlaxoSmithKline) to perform phase 3 clinical vaccine trials. She has received speaking fees from MSD for work performed in her personal time and Merck paid for travel and accommodation to present at Global HPV Advisory board meetings. DAM, JMK and RG are investigators on a genital warts surveillance grant funded by Sequiris. All other authors declare no conflicts of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background Patient-delivered partner therapy (PDPT) for chlamydia is an effective and safe additional partner management strategy. Some Australian regulatory changes have been made to support PDPT, but implementation guidance is lacking. This paper describes a pilot implementation program of PDPT in New South Wales (NSW), the Australian Development and Operationalisation of Partner Therapy (ADOPT)., Methods: ADOPT involved: (1) clarification of the NSW PDPT legal and policy framework; (2) development and implementation of PDPT service models, resources and data collection tools for select publicly funded sexual health services (PFSHS) and Family Planning (FP) NSW clinics; and (3) evaluation of PDPT uptake., Results: PDPT can be undertaken in NSW if accompanied by adequate provider, patient and partner information. Regulatory amendments enabled medication prescribing. The pilot implementation took place in four PFSHS and five FPNSW clinics from January to December 2016. In PFSHS, 30% of eligible patients were offered PDPT and 89% accepted the offer. In FPNSW clinics, 42% of eligible patients were offered PDPT and 63% accepted the offer. Most partners for whom PDPT was accepted were regular partners., Conclusions: A close collaboration of researchers, policy makers and clinicians allowed successful implementation of a PDPT model for chlamydia in heterosexual patients at select PFSHS and FPNSW clinics, providing guidance on its use as standard of care. However, for the full public health benefits of PDPT to be realised, it must be implemented in general practice, where most chlamydia is diagnosed. Further work is recommended to explore feasibility, develop guidelines and promote the integration of PDPT into general practice.

We analysed data from a prospective cohort of 255,024 adults aged ⩾45 years recruited from 2006-2009 to identify characteristics associated with a zoster diagnosis. Diagnoses were identified by linkage to pharmaceutical treatment and hospitalization records specific for zoster and hazard ratios were estimated. Over 940,583 person-years, 7771 participants had a zoster diagnosis; 253 (3·3%) were hospitalized. After adjusting for age and other factors, characteristics associated with zoster diagnoses included: having a recent immunosuppressive condition [adjusted hazard ratio (aHR) 1·58, 95% confidence interval (CI) 1·32-1·88], female sex (aHR 1·36, 95% CI 1·30-1·43), recent cancer diagnosis (aHR 1·35, 95% CI 1·24-1·46), and severe physical limitation vs. none (aHR 1·33, 95% CI 1·23-1·43). The relative risk of hospitalization for zoster was higher for those with an immunosuppressive condition (aHR 3·78, 95% CI 2·18-6·55), those with cancer (aHR 1·78, 95% CI 1·24-2·56) or with severe physical limitations (aHR 2·50, 95% CI 1·56-4·01). The novel finding of an increased risk of zoster diagnoses and hospitalizations in those with physical limitations should prompt evaluation of the use of zoster vaccine in this population.

Background: For the past two decades, chlamydia has been the most commonly notified infectious disease among young people (15-29 year olds) in Australia, the United States of America and the United Kingdom and rates have increased annually in these three countries. In Australia, rates of chlamydia are three times higher in Aboriginal compared with non-Aboriginal people. Australian sexually transmissible infection guidelines recommend annual chlamydia testing for 15-29 year old females and males. This analysis will examine the incidence and predictors of annual chlamydia testing in 15-29 year olds attending four Aboriginal Community Controlled Health Services (ACCHS) in Australia., Methods: From 2009-2011, attendance and chlamydia testing data were extracted from the patient system to calculate the number and proportion of 15-29 year olds that were tested for chlamydia and that tested positive for chlamydia by gender (male, female), age-group (15-19, 20-24, 25-29 years), Aboriginal status (Aboriginal, non-Aboriginal people) and by the four ACCHSs sites (1, 2, 3 and 4). A cohort was created to calculate the incidence rate per 100 person-years (PY) and predictors of an annual chlamydia test (a test within 12-months of a previous test/visit) by the above factors using Cox regression. Unadjusted and adjusted hazard ratios (AHR) and their 95 % confidence intervals (CIs) and p-values were calculated with significance at p < 0.05., Results: From 2009-2011, there were 2896 individuals who attended the four ACCHSs. Overall , 17 % (22 % of females and 10 % of males) were tested for chlamydia and 9 % tested positive (8 % of females and 14 % of males). The median time to an annual chlamydia test was 10.7 months. The cohort included 2318 individuals. Overall the incidence rate of an annual chlamydia test was 9.1 per 100 PY (11.6 in females and 5.8 in males). Predictors of an annual chlamydia test were being female (AHR: 1.7, 95 % CI: 1.2-2.2, p < 0.01), being 15-19 years old (AHR: 1.6, 95 % CI: 1.1-2.3, p < 0.01) and attending ACCHS site 2 (AHR: 3.8, 95 % CI: 1.8-8.0, p < 0.01)., Conclusions: This analysis highlights that opportunistic STI testing strategies are needed to increase annual chlamydia testing in young people; especially males.

Background: Hepatitis C virus (HCV) infection is common in prisoner populations, particularly those with a history of injecting drug use (IDU). Previous studies of HCV incidence have been based on small case numbers and have not distinguished risk events in prison from those in the community., Methods: HCV incidence was examined in a longitudinal cohort of 488 Australian prisoners with a history of IDU and documented to be seronegative within 12 months prior to enrollment. Inmates were tested for anti-HCV antibodies and viremia, and interviewed about demographic and behavioral risk factors for transmission., Results: The cohort was predominantly male (65%) with high rates of prior imprisonment (72%) and tattooing (73%), as well as longstanding IDU (mean 8.5 years). Ninety-four incident HCV cases were identified (incidence 31.6 per 100 person years). Independent associations were observed between incident infection and prior imprisonment (p = 0.02) and tattooing (p = 0.03), and surprisingly also with methadone maintenance treatment (MMT) (p < 0.001)., Conclusions: High rates of new HCV infection were found in this prisoner cohort reflecting their substantive risk behavior profile, despite having remained uninfected for many years. The association with MMT is challenging and highlights the need for better understanding of prison-specific HCV transmission risks, as well as the uptake and effectiveness of prevention programs.

Aims: Supervised injecting facilities (SIFs) are effective in reducing the harms associated with injecting drug use among their clientele, but do SIFs ease the burden on ambulance services of attending to overdoses in the community? This study addresses this question, which is yet to be answered, in the growing body of international evidence supporting SIFs efficacy., Design: Ecological study of patterns in ambulance attendances at opioid-related overdoses, before and after the opening of a SIF in Sydney, Australia., Setting: A SIF opened as a pilot in Sydney's 'red light' district with the aim of accommodating a high throughput of injecting drug users (IDUs) for supervised injecting episodes, recovery and the management of overdoses., Measurements: A total of 20,409 ambulance attendances at opioid-related overdoses before and after the opening of the Sydney SIF. Average monthly ambulance attendances at suspected opioid-related overdoses, before (36 months) and after (60 months) the opening of the Sydney Medically Supervised Injecting Centre (MSIC), in the vicinity of the centre and in the rest of New South Wales (NSW)., Results: The burden on ambulance services of attending to opioid-related overdoses declined significantly in the vicinity of the Sydney SIF after it opened, compared to the rest of NSW. This effect was greatest during operating hours and in the immediate MSIC area, suggesting that SIFs may be most effective in reducing the impact of opioid-related overdose in their immediate vicinity., Conclusions: By providing environments in which IDUs receive supervised injection and overdose management and education SIF can reduce the demand for ambulance services, thereby freeing them to attend other medical emergencies within the community.

To determine hepatitis C incidence and the demographic and behavioural predictors in seronegative drug injecting prisoners. Prisoners in New South Wales, Australia who: were aged 18 years and over; reported IDU; had been continuously imprisoned; had a documented negative HCV antibody test result in prison in the last 12 months; provided written informed consent. Subjects were interviewed about their demographic characteristics and detailed risk factors for transmission prior to, and since, imprisonment. A blood sample was collected to screen for HCV antibodies by ELISA and RNA by PCR. Of 253 inmates recruited, 120 were continuously imprisoned and included in this analysis. Sixteen acquired HCV infection indicating an incidence of 34.2 per 100 person years (CI: 19.6-55.6). Risk factors for transmission included prior imprisonment, methadone treatment and greater than 10 years of education. Although the frequency of injecting was reduced in prison, 33.6% continued to inject drugs, most commonly methamphetamine, and 90% of these reported sharing injecting equipment. Prison inmates were at high risk of HCV infection, despite some reduction in high-risk behaviours and access to prevention services. To prevent HCV transmission in prisons, better prevention strategies are required.

Objective: To determine risk factors and estimate their population-level contribution to hepatitis C virus (HCV) burden., Methods: Established and potentially modifiable risk factors were estimated using partial population attributable risk (PAR(p)) in a cohort of new injecting drug users (IDUs) in Sydney, Australia., Results: A total of 204 hepatitis C seronegative IDUs were recruited through street-based outreach, methadone clinics and needle and syringe programmes (NSPs) and followed-up at 3-6-monthly intervals. A total of 61 HCV seroconversions were observed during the follow-up [overall incidence rate of 45.8 per 100 person-years (95% confidence interval: 35.6-58.8)]. Overall, five potentially modifiable risk factors (sharing needles/syringes, sharing other injecting equipment, assisted injecting, frequency of injection and not being in drug treatment) accounted for approximately 50% of HCV cases observed., Conclusion: While sharing needles/syringes or other injecting equipment were associated most strongly with increased risk of HCV infection, the PAR(p) associated with these behaviours was relatively modest (12%) because they are relatively low-prevalence behaviours. Our analyses suggest that more HCV infection could be avoided by changing more common, but less strongly associated behaviours such as assisted injecting or daily injecting. Results suggest that to have a very substantial effect on HCV, a range of risk factors need modifying. The most efficient use of scarce resources in reducing HCV infections will require complex balancing between the PAR for a given risk factor(s), the efficacy of interventions to actually modify the risk factor, and the cost of these interventions.

Spatio-temporal clustering of sporadic Creutzfeldt-Jakob disease (sCJD) has been recognized and investigated previously in various global settings including Australia. Generally, despite often extensive investigation, explanations such as point source outbreaks and plausible case-to-case transmission links have not been identified to explain the apparently higher case rates than expected. In the context of national surveillance during the period 1993-2006, an increased number of cases of sCJD were recognized in a circumscribed coastal region of eastern Australia. To assess the significance of this apparent clustering, the Spatial Scan Statistic was used to examine for geographic excess of CJD mortality at spatial and temporal combined, spatial only and temporal only levels. A significant spatial cluster was confirmed, encompassing three contiguous statistical local areas within the state of New South Wales (NSW). Detailed epidemiological analysis did not reveal a plausible cross-over or point source transmission event. Further evaluation prompted the conclusion that vigilant and motivated managing clinicians in this geographically circumscribed area of NSW evinced a sustained higher level of clinical awareness for the broad phenotypic spectrum of CJD with reliable referral of suspect cases for further investigation. In addition, these physicians established and maintained a well-coordinated and active approach to suspect CJD autopsy. This combination of factors translated into a higher intensity of surveillance at approximately twice the rate per population observed in the entire state, culminating in twice the incidence of sCJD at around 2.28 cases/million population/year. The hypothesis that intensity of surveillance for rare disorders can be objectively measured and that this can positively correlate with disease incidence deserves further exploration. It may prove to be an important insight into the varying incidence rates over periods of time within individual nations and between different countries.

Objectives: To determine the prevalence, incidence and risk factors for pharyngeal Chlamydia trachomatis in the community based Health in Men (HIM) cohort of HIV negative homosexual men in Sydney, Australia., Methods: From January 2003, all HIM participants were offered annual screening for pharyngeal chlamydia using BD ProbeTec nucleic acid amplification testing (NAAT). Detailed sexual behavioural data were collected every 6 months, and risk factors for infection and hazard ratios were calculated using Cox regression., Results: Among 1427 participants enrolled, the prevalence of pharyngeal chlamydia on initial testing was 1.06% and the incidence rate was 0.58 per 100 person-years. More than 50% of all infections were identified on baseline testing and 68% of men with pharyngeal infection had no evidence of concurrent anogenital chlamydia. There was no association of pharyngeal chlamydia with sore throat. Infection was significantly associated with increasing frequency of receptive penile-oral sex with ejaculation with casual partners (p = 0.009), although approximately half of infections occurred in participants not reporting this risk behaviour. Neither kissing nor oro-anal practices were associated with infection., Conclusion: The incidence of pharyngeal chlamydia infection in the HIM study was relatively low; however, the relatively high prevalence on baseline testing compared to incidence suggests a long duration of infection. Occasional screening for pharyngeal chlamydia in homosexual men who frequently practise receptive oral sex with ejaculation may be warranted.

Background: Since 1999 there has been an increase in the number of HIV diagnoses in Australia, predominantly among men who have sex with men (MSM), but the magnitude of increase differs between states: approximately 7% rise in New South Wales, approximately 96% rise in Victoria, and approximately 68% rise in Queensland., Methods: Epidemiological, clinical, behavioural and biological data were collated into a mechanistic mathematical model to explore possible reasons for this increase in HIV notifications in MSM. The model was then used to make projections to 2015 under various scenarios., Results: The model suggests that trends in clinical and behavioural parameters, including increases in unprotected anal intercourse, cannot explain the magnitude of the observed rise in HIV notifications, without a substantial increase in a 'transmission-increasing' factor. We suggest that a highly plausible biological factor is an increase in the prevalence of other sexually transmissible infections (STI). It was found that New South Wales required an approximately 2-fold increase in other STI to match the data, Victoria needed an ~11-fold increase, and Queensland required an approximately 9-fold increase. This is consistent with observed trends in Australia for some STI in recent years. Future projections also indicate that the best way to control the current rise in HIV notifications is to reduce the prevalence of other STI and to promote condom use, testing for HIV, and initiation of early treatment in MSM diagnosed during primary infection., Conclusions: Our model can explain the recent rise in HIV notifications with an increase in the prevalence of other STI. This analysis highlights that further investigation into the causes and impact of other STI is warranted in Australia, particularly in Victoria.

Objective: Misreporting of circumcision status may affect observed relationships between circumcision status and HIV or other sexually transmissible infections. As no data exist on the validity of self-reported circumcision status among homosexual men, we investigated the agreement between self-report and examination findings in a subgroup of participants in the Health in Men (HIM) study in Sydney, Australia., Methods: A subgroup of 240 participants in the community based HIM cohort study attending annual interview agreed to a brief genital examination by a trained study nurse who was unaware of their previous self-reported circumcision status., Results: Five participants reported being uncircumcised at baseline but were classified as circumcised on examination. All participants who self-reported being circumcised were found on examination to be circumcised. Three cases in which the examining study nurse was unsure of participants' circumcision status were excluded. Of the remaining 237 participants, 155 (65.4%) were classified as circumcised on examination, including five men who self identified as uncircumcised. Compared with examination, self-reported circumcision status resulted in a sensitivity of 96.8%, specificity of 100%, positive predictive value of 100% and negative predictive value of 94.3%. The overall agreement between circumcision status on examination and self-report was 97.9% (kappa score, 0.95; p<0.001), Conclusion: Self-report was a valid measure of circumcision status in this group of predominantly Anglo gay-community-attached men. We believe our findings can be generalised to similarly aged gay-community-attached men in other developed countries.

Background: Rates of use of amphetamine type stimulants among gay men have raised questions about the role of these drugs in increases in HIV infections and risk behaviour, but the role risk behaviours play with regard to illicit drug use within this population has not been investigated., Method: Health in men (HIM) is a cohort of 1427 HIV-negative men in Sydney, Australia. All participants undergo annual face-to-face interviews. We examined onset of use of methamphetamine and of ecstasy (MDMA) after their baseline interview., Results: Among baseline non-frequent users who completed an annual follow-up interview, 67 commenced at least weekly use of ecstasy, while 71 commenced at least weekly use of methamphetamine. Factors independently associated with commencing more frequent use of these drugs included being younger, greater involvement in gay social life, and having engaged in unprotected anal intercourse with casual partners., Conclusions: The transition from non- or less-frequent drug use to more frequent drug use may be associated with changes in sexual behaviour. While it may be true that illicit drug use leads to unsafe sexual behaviour, it is equally true that illicit drugs are used to enhance sexual performance and pleasure. The relationship is bidirectional and complex and must be understood within the contexts of particular sexual sub-cultural practices: engaging in sexual risk behaviour may be an indicator of future drug use as much as the reverse.

Background/aims: Hepatocellular carcinoma (HCC) incidence has increased in Australia in the past 20-30 years. We conducted a community-based linkage study to examine the characteristics of hepatocellular carcinoma with particular reference to hepatitis B and C infections., Methods: Hepatocellular carcinoma cases (n=2,072) notified to the New South Wales (NSW) Central Cancer Registry from 1990 to 2002 were probabilistically linked to HBV and HCV diagnoses notified to NSW Health. Sex, age, year of diagnosis, region of birth, method of diagnosis and spread at diagnosis and survival were compared by linkage group., Results: Hepatocellular carcinoma incidence increased from 1.4/100,000 in 1990 to 2.8/100,000 in 2002. Incidence varied by region of birth (p<0.001), with people born in Vietnam having the highest relative rate compared with those born in Australia (RR=11.7, 95% CI 9.8-13.8). Of the hepatocellular carcinoma records, 15.6%, 12.9% and 0.8% were linked to hepatitis B, hepatitis C and hepatitis B/C co-infection respectively and 70.7% were unlinked. Median age at diagnosis of HCV-related hepatocellular carcinoma varied markedly at 51, 68 and 71 years for Australian, European, and Asian-born groups, respectively (p<0.0001)., Conclusion: Contrasting age distribution of HCV-related HCC by country/region of birth is consistent with divergent patterns of HCV transmission., Implications: These data highlight the increase in HCC in NSW and the divergent populations whose needs in terms of treatment, care and prevention will need to be met.

Objective: To investigate the association between occupational exposure to ionizing, ultraviolet (UV), radiofrequency (RF) and extremely low frequency (ELF) radiation and risk of developing non-Hodgkin lymphoma (NHL) in a population-based case-control study., Methods: The study population consisted of 694 NHL cases, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupation history was first obtained using a lifetime calendar and a telephone interview. Exposure to radiation was then assessed using a Finnish job-exposure matrix (FINJEM). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression models that included the matching variables as covariates., Results: For ionizing radiation, the ORs were close to unity. For UV and ELF radiation, the highest exposed group of workers had ORs of 1.32 (95% CI=0.96-1.81) and 1.25 (95% CI=0.91-1.72), respectively. For UV radiation there was a positive dose-response when exposure was lagged by 5 and 10 years (P for trend 0.04 for both lag periods). Workers in the upper tertile of exposure for RF radiation had an OR of 3.15 (95% CI=0.63-15.87), but the estimate was based on very small numbers., Conclusions: Our results do not provide support for an association between NHL and occupational exposure to ionizing or ELF radiation. For UV radiation, our findings are consistent with a weak positive association. Further investigation focusing on UV and RF radiation and NHL is required.

Background: Early detection and treatment of bacterial sexually transmitted infections has been advocated as an HIV prevention strategy., Aim: To inform screening guidelines, the incidence and risk factors for urethral and anal gonorrhoea and chlamydia were studied in a prospective cohort of community-based HIV negative homosexual men in Sydney, New South Wales, Australia., Methods: All participants were offered annual screening for gonorrhoea and chlamydia (study-visit diagnoses) on urine and anal swabs using nucleic acid amplification. Participants also reported diagnoses of gonorrhoea and chlamydia made elsewhere between interviews (interval diagnoses). All diagnoses were summed to create a combined incidence rate, and detailed data on specific sexual practices with casual and regular partners were collected., Results: Among 1427 men enrolled, the combined incidence rates were 3.49 and 2.96 per 100 person-years for urethral and anal gonorrhoea, respectively; and 7.43 and 4.98 per 100 person-years for urethral and anal chlamydia, respectively. Urethral infections were associated with unprotected anal intercourse (UAI) with HIV-positive partners (hazard ratio (HR) = 2.58, 95% CI 1.10 to 6.05 for urethral gonorrhoea) and with frequent insertive oral sex (p for trend 0.007 for urethral chlamydia). Anal infections were associated with receptive UAI (p for trend 0.001 for both anal gonorrhoea and chlamydia) and other receptive anal sexual practices. Stratified analyses showed the independence of the associations of insertive oral sex with urethral infections and of non-intercourse receptive anal practices with anal infections., Conclusion: Incident gonorrhoea and chlamydia were common. Risk behaviours for both urethral and anal infections were not restricted to UAI. Screening that includes tests for anal and urethral infections should be considered for all sexually active homosexual men, not just for those who report UAI.

Objectives: To investigate the risk of non-Hodgkin lymphoma (NHL) using a job-exposure matrix (JEM) to assess exposure to occupational magnetic fields at the power frequencies of 50/60 Hz., Methods: The study population consisted of 694 cases of NHL, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupational history was given by each subject. Exposure to power frequency magnetic fields was estimated using a population-based JEM which was specifically developed in the United States to assess occupational magnetic field exposure. The cumulative exposure distribution was divided into quartiles and adjusted odds ratios were calculated using the lowest quartile as the referent group., Results: For the total work history, the odds ratio (OR) for workers in the upper quartile of exposure was 1.48 (95% CI 1.02 to 2.16) compared to the referent (p value for trend was 0.006). When the exposure was lagged by 5 years the OR was 1.59 (95% CI 1.07 to 2.36) (p value for trend was 0.003). Adjusting for other occupational exposures did not significantly alter the results., Conclusions: These findings provide weak support for the hypothesis that occupational exposure to 50/60 Hz magnetic fields increases the risk of NHL.

Past research on unprotected anal intercourse with casual partners (UAIC) contrasts those who report no UAIC with any UAIC. This paper examines differences among three groups of men who had any UAIC on the basis of the number of UAIC acts reported in a six-month period, namely no UAIC (n = 507), occasional UAIC (1-5 acts, n = 251) and frequent UAIC (more than 5 acts, n = 148). The occasional UAIC group had values lying between those of the no- and the frequent-UAIC group. As compared with the frequent-UAIC group, men in the occasional-UAIC group were less likely to have a steady partner, held less favorable attitudes toward condoms and higher levels of HIV treatments optimism and were more likely to report some disclosure of serostatus to or by casual partners and a range of esoteric sexual practice. On the other hand, men in the no-UAIC group had lower levels of 'feeling bad' (distress) and were less likely to use drugs to enhance sexual pleasure in casual encounters. Disclosure of serostatus had a strong association with frequent UAIC and this finding calls for both more research and more community exploration of issues surrounding sexual decision-making.

To assess whether workers at Lucas Heights Science and Technology Centre (LHSTC) had different levels of cancer incidence from the New South Wales (NSW) population in Australia. A retrospective cohort study was undertaken at LHSTC. Data on 7,076 workers employed between 1957-98 were abstracted from personnel, dosimetry, and medical files. An inception cohort was defined which included 4,523 workers in employment between 1972-96 to examine cancer incidence. Cancer registrations in the inception cohort were identified to 1996 through electronic linkage of records with the NSW and the Australian national registers of cancer incidence. All-cancer incidence in workers at LHSTC was 15% below the NSW rates [SIR=0.85; 95% CI=(0.75, 0.95)]. Of 37 specific cancers and groups of cancers examined, statistically significant excesses relative to NSW rates were observed only for pleural cancer incidence [SIR=17.71; 95%=(7.96, 39.43)], and for incidence of cancer of the small intestine [SIR=4.34; 95% CI=(1.40, 13.46)]. This study gives little evidence of an increased risk of cancers associated with radiation exposure in a cohort of nuclear workers in Australia. The observed increase in the risk of cancer of the pleura was probably due to unmeasured exposures, given the lack of an established association with radiation exposure, and the strong link to asbestos exposure. Findings for cancers of the small intestine were based on small numbers and were likely to be due to chance.

Objective: To report changes in sexual behaviour among gay men in Sydney from 1986 to 2003., Methods: Baseline data from four studies of gay men in Sydney were used: the Social Aspects of the Prevention of AIDS study (1986/87: 91 HIV-positive and 444 HIV-negative men); the Sydney Men and Sexual Health cohort (1993-95: 237 HIV-positive and 910 HIV-negative men); the Health in Men cohort of HIV-negative gay men (2001-03: 1,148 men); the Positive Health cohort of HIV-positive gay men (2001/02: 237 men). Each sample was recruited and interviewed using similar methods., Results: Fewer HIV-positive men had sex with casual partners over time (76.9% in 1986/87 to 63.7% in 2001/02; p = 0.001), but more HIV-negative men had sex with 10 or more casual partners in the previous six months (27.7% in 1986/87 to 37.7% in 2001-03; p = 0.012). The proportions engaging in particular sex practices with casual partners changed over time: anal intercourse without condoms that included ejaculation in the rectum fell from 29.4% among HIV-positive men and 32.4% among other men in 1986/87 to 17.8% and 10.0% respectively in 1993-95 (p = 0.034 and p < 0.001 respectively), but increased to 37.7% and 18.4% respectively in 2001-03 (p-values < 0.001); rimming one's partner increased from 36.8% among HIV-positive men and 17.6% among other men in 1986/87 to 63.6% and 52.3% respectively in 2001-03 (p = 0.001 and p < 0.001 respectively)., Conclusion: Gay men's sexual behaviour with casual partners has changed over time, perhaps partly in response to HIV and partly as a general expansion of sexual repertoires. These changes have implications for gay men's health.

Objective: The effectiveness of the National Death Index (NDI) in identifying deaths among different populations has been studied before. Prisoners represent a segment of the population that might be expected to be difficult to link. The objective of this research was to evaluate the accuracy of the Australian NDI to ascertain the mortality status of prisoners in New South Wales, Australia., Methods: Data on 311 inmates who had died in custody between January 1988 and March 2003, and on 7,558 inmates known to be alive at the end of May 2003, were matched to the NDI database. Matching was undertaken using a probabilistic linkage method followed by a clerical review. The underlying causes of death reported by the NDI were compared against those reported by the NSW Coroner and held at the Legal Branch of the Department of Corrective Services., Results: Linkage correctly identified 275 of the 311 known deaths (sensitivity: 88.4%). Of the 7,558 prisoners known to be alive in custody at the end of May 2003, linkage to the NDI incorrectly identified 23 as dead (specificity: 99.7%). Cause of death was accurately reported by the NDI for 95.5% of deaths identified by the linkage., Conclusion: The results of this study show that the NDI is an accurate and feasible means for evaluating mortality among prisoners. The nature of the prisoner population makes the linkage a difficult task for the NDI. The success of the data linkage depends on the extent and accuracy of information contained in the index file and type and quality of information available.

Objectives: To assess whether workers at Lucas Heights Science and Technology Centre (LHSTC) have different levels of mortality from the New South Wales (NSW) and Australian populations., Methods: A retrospective cohort study was undertaken at LHSTC. Data on 7,076 workers employed between 1957-98 were abstracted from personnel, dosimetry, and medical files. Deaths registrations in the cohort were identified to 1998 through electronic linkage of records with NSW and national registers of cancer incidence and mortality. Two inception cohorts were defined as including 4,717 and 3,543 workers in employment between 1972-98 and 1980-98, to examine cancer mortality and all-cause mortality respectively., Results: All-cause mortality was 31% lower than the national rates; all-cancer mortality was 19% below the NSW rate. Of 37 specific cancers and groups of cancers examined, statistically significant excesses relative to NSW rates were observed only for pleural cancer mortality (SMR = 21.11; 95% Cl 8.79-50.72)., Conclusions: The observed increase in the risk of cancer of the pleura was probably due to unmeasured exposures, given the lack of an established association with radiation exposure and the strong link to asbestos exposure.

Aims: To examine the long-term impact of methadone maintenance treatment (MMT) on mortality, re-incarceration and hepatitis C seroconversion in imprisoned male heroin users., Design, Setting and Participants: The study cohort comprised 382 imprisoned male heroin users who had participated in a randomized controlled trial of prison-based MMT in 1997/98. Subjects were followed-up between 1998 and 2002 either in the general community or in prison., Measurements: All-cause mortality, re-incarceration, hepatitis C and HIV serostatus and MMT retention., Findings: There were no deaths recorded while subjects were enrolled in MMT. Seventeen subjects died while out of MMT, representing an untreated mortality rate of 2.0 per 100 person-years (95% CI, 1.2-3.2). Re-incarceration risk was lowest during MMT episodes of 8 months or longer (adjusted hazard ratio 0.3 (95% CI, 0.2-0.5; P < 0.001), although MMT periods 2 months or less were associated with greatest risk of re-incarceration (P < 0.001). Increased risk of hepatitis C seroconversion was significantly associated with prison sentences of less than 2 months [adjusted hazard ratio 20 (95% CI, 5-76; < P = 0.001)] and MMT episodes less than 5 months [adjusted hazard ratio 4.2 (95% CI, 1.4-12.6; P = 0.01)]. Subjects were at greatest risk of MMT dropout during short prison sentences of 1 month or less (adjusted hazard ratio 10.4 (95% CI, 7.0-15.7; P < 0.001). HIV incidence was 0.3 per 100 person-years (95% CI, 0.03-0.99)., Conclusions: Retention in MMT was associated with reduced mortality, re-incarceration rates and hepatitis C infection. Prison-based MMT programmes are integral to the continuity of treatment needed to ensure optimal outcomes for individual and public health.

Background: We conducted a retrospective study to determine if potential past exposure to dioxin had resulted in increased incidence of cancer in people living near a former manufacturing plant in New South Wales, Australia. During operation, from 1928 to 1970, by-products of the manufacturing process, including dioxin and other chemical waste, were dumped into wetlands and mangroves, discharged into a nearby bay and used to reclaim land along the foreshore, leaving a legacy of significant dioxin contamination., Methods: We selected 20 Census Collector Districts within 1.5 kilometres of the former manufacturing plant as the study area. We obtained data on all cases of cancer and deaths from cancer in New South Wales from 1972 to 2001. We also compared rates for some cancer types that have been associated with dioxin exposure. Based on a person's residential address at time of cancer diagnosis, or at time of death due to cancer, various geo-coding software and processes were used to determine which collector district the case or death should be attributed to. Age and sex specific population data were used to calculate standardised incidence ratios and standardised mortality ratios, to compare the study area to two comparison areas, using indirect standardisation., Results: During the 30-year study period 1,106 cases of cancer and 524 deaths due to cancer were identified in the study area. This corresponds to an age-sex standardised rate of 3.2 cases per 1,000 person-years exposed and 1.6 deaths per 1,000 person-years exposed. The study area had a lower rate of cancer and deaths from cancer than the comparison areas. The case incidence and mortality due to lung and bronchus carcinomas and haematopoietic cancers did not differ significantly from the comparison areas for the study period. There was no obvious geographical trend in ratios when comparing individual collector districts to New South Wales according to distance from the potential source of dioxin exposure., Conclusion: This investigation found no evidence that dioxin contamination from this site resulted in increased cancer rates in the potentially exposed population living around the former manufacturing plant.

Objective: To determine whether reporting that the HIV-positive partner's viral load is undetectable rather than detectable is associated with unprotected anal intercourse (UAI) in HIV serodiscordant gay couples., Method: A cross-sectional study nested within two cohort studies, the Health in Men (HIM) cohort of HIV-negative men, from July 2001 to December 2003 and the Positive Health (PH) cohort of HIV-positive men, from February 2002 to August 2003. The study participants were 119 men in an HIV serodiscordant regular relationship of at least 6 months duration (45 HIV-negative men from HIM, 74 HIV-positive men from PH). The main outcome measure was the occurrence of UAI within the relationship in the previous 6 months., Results: Eighty-two men reported no UAI and 37 reported some UAI. Of couples in which the HIV-positive partner's viral load was reported to be undetectable, 39.4% reported UAI compared with 20.8% of those where viral load was reported to be detectable (P = 0.04). In multivariate analysis, significant predictors of UAI were younger age [odds ratio (OR), 0.94; 95% confidence interval (CI), 0.87-1.00; P = 0.05], greater HIV optimism (OR, 4.98; 95% CI, 1.25-19.8; P = 0.02) and reported undetectable viral load (OR, 2.88; 95% CI, 1.13-7.37; P = 0.03)., Conclusions: Most serodiscordant gay couples do not engage in any UAI. UAI within such relationships is significantly more likely to occur where the HIV-positive partner is reported to have undetectable viral load. UAI in HIV serodiscordant relationships is problematic even if viral load is undetectable because of unknown risk parameters, viral load variability and the possibility of drug-resistant strains of HIV.

The objective of the paper was to compare encounters involving unprotected anal intercourse (UAI) and protected anal intercourse (PAI) among HIV-negative gay men in Sydney. Data were from those completing baseline face-to-face interviews to end June 2003 for the Health in Men open cohort of HIV-negative gay men in Sydney. The 1,148 participants ranged in age from 18 to 75 years (median = 36). Three hundred and fifty-two (30.7%) reported an occasion of UAI with a casual partner in the previous 6 months and 531 (46.3%) reported an occasion of UAI with a regular partner in that same time. The men's most recent sexual contact with a casual partner involving UAI was distinguished from those involving PAI by a greater likelihood for both partners to disclose HIV serostatus (p = 0.006) and by respondents being more inclined to restrict themselves to the insertive position or to practise withdrawal during occasions involving any UAI than when a condom was used (p = 0.003 and p = 0.001 respectively). Neither location nor recreational drug use differentiated men's most recent sexual contacts involving UAI from those involving PAI. The decision by HIV-negative gay men to use condoms during sexual encounters with either regular or casual partners is guided more by HIV serostatus and risk reduction strategies than by other factors.

Hepatitis C is the most commonly notified disease in Australia. In 1998 the Hepatitis C Virus Projections Working Group (HCPWG) estimated that there were approximately 210,000 people who had been infected by hepatitis C virus (HCV) in Australia by 2001. Population-based serosurveys are required to validate this estimate. Here we estimate HCV prevalence on the basis of HCV antibody seroprevalence in the Australian national serosurvey. Between 1996 and 1998, 2,800 sera opportunistically collected from pathology laboratories throughout Australia were tested for HCV antibody. National HCV notifications reported from 1991 through 1998 were also assessed. Eighty-one sera were HCV antibody positive, giving an age standardised prevalence of 2.3 per cent (95% CI 1.8%-2.9%). The 20-24 year age group had the highest HCV prevalence, 5.3 per cent (95% CI 3.3%-8.1%) and the male to female ratio was 1.8:1.0. Approximately 111,000 HCV notifications were received from 1991 through 1998. HCV prevalence estimated by the serosurvey is approximately three times higher than cumulative HCV notifications. Age and sex distributions of seroprevalence are broadly consistent with cumulative notification data. These distributions are consistent with the majority of HCV infections in Australia being transmitted by injecting drug use. Very low age specific seroprevalence estimates in the over 50 years age group indicate that there is not a large pool of undiagnosed infection in this age group. The serosurvey provides an estimate of Australian HCV prevalence and baseline data to determine incidence trends, both of which are required for health-care planning.

Objectives: To investigate a cluster of leukaemia among young people and assess the plausibility of a disease-exposure relationship., Design: Descriptive analysis of population-based leukaemia incidence data, review of evidence related to the causation of leukaemia, assessment of environmental exposures to known leukaemogens, and resulting risks of leukaemia., Setting: Illawarra region of New South Wales, Australia, focusing on suburbs between the Port Kembla industrial complex and Lake Illawarra (the Warrawong area)., Main Outcome Measures: Standardised incidence ratios (SIRs) for leukaemia; current measured and past estimated ambient air benzene concentrations; and expected leukaemia cases attributable to estimates of ambient air benzene concentrations., Results: In 1989-1996, 12 leukaemia cases among Warrawong residents aged less than 50 years were observed, more than the 3.49 cases expected from the rate in the rest of the Illawarra region (SIR, 343.8; 99% CI, 141.6-691.7). These people lived in suburbs immediately to the south-southwest of a coke byproducts plant (a major industrial source of benzene, one of the few known leukaemogens). The greatest excess was among 15-24-year-olds (SIR, 1085.6; 99% CI, 234.1-3072.4). In 1996, ambient air concentrations of benzene averaged less than 1 part per billion (ppb). Since 1970, ambient air concentrations of benzene were estimated to have averaged up to 3 ppb, about one-thousandth of the level at which leukaemia risk has been identified in occupational epidemiological studies. Using the risk assessment model developed by the US Environmental Protection Agency, we estimate that past benzene levels in the Warrawong area could have resulted in 0.4 additional cases of leukaemia in 1989-1996., Conclusions: The excess occurrence of leukaemia in the Warrawong area in 1989-1996 is highly unusual. Current environmental benzene exposure and the reconstructed past environmental benzene exposure level are too low to explain the large excess of leukaemia. The cause of the cluster is uncertain.

Objectives: 1. Establish the prevalence of markers for hepatitis B (HBV), C (HCV) and G (HGV) in a sample of male and female inmates. 2. Examine exposure to multiple viruses. 3. Compare risk factors for HGV infection with known risk factors for HBV and HCV., Design: Cross-sectional random sample stratified by sex, age and Aboriginality. Inmates were screened for three hepatitis markers. Participants were 789 inmates (657 male, 132 female) in 27 correctional centres in New South Wales, 1996., Results: Overall detection of each of the three screening markers was 35% for HBV, 39% for HCV and 10% for HGV. Exposure rates were higher in female prisoners than males. Increased rates of anti-HBc were observed in Aboriginal inmates compared with non-Aboriginals (54% cf. 27%); anti-HCV and HGV-RNA were comparable between the two groups (36% cf. 41% and 9% cf. 10%). Markers were significantly higher in female injecting drug users (IDU), particularly HCV (90% cf. 66%). Thirty-five per cent of inmates were unaware of their HCV status. For HBV, 72% did not self-report past or present exposure despite serological evidence to the contrary. The multivariate analysis identified Aboriginality, long-term injecting and injecting while in prison as risk factors for HBV. HCV risk factors were female sex, non-Aboriginality, institutionalisation and IDU-associated behaviours. For HGV, female sex and previous imprisonment were significant risk factors but IDU was not., Conclusions: Blood-borne hepatitis viruses are common in prison inmates, particularly females (HBV, HCV and HGV), Aboriginals (HBV) and IDU (HBV and HCV). Infection can be related to a number of risk factors, which appear similar for HBV and HCV, but distinct from HGV.

Objectives: To determine whether the incidence of cancers other than the AIDS-defining cancers is increased in people with AIDS, and to determine if cancer incidence increases with time, a surrogate marker of declining immune function., Design: Register-based retrospective cohort study in New South Wales, Australia. Age-, sex-, and period-adjusted standardized incidence ratios (SIR) were calculated for individual cancers occurring in 1980-1993 in people with AIDS registered before 1996., Results: During the study period, 3616 people were registered with AIDS; 716 cases of AIDS-defining cancer and 62 cases of non-AIDS-defining cancer were identified. People with AIDS had a significantly increased incidence of Hodgkin's disease [SIR 18.3; 95% confidence interval (CI) 8.39-34.8], multiple myeloma (SIR 12.1; 95% CI 2.50-35.4), leukaemia (SIR 5.76; 95% CI 1.57-14.7), lip cancer (SIR 5.94; 95% CI 1.92-13.8) and lung cancer (SIR 3.80; 95% CI 1.39-8.29). The incidence of Hodgkin's disease increased significantly around the time of AIDS diagnosis (P = 0.008 for trend with time), suggesting an association with immunodeficiency., Conclusions: This study provides strong support for the hypothesis that Hodgkin's disease is an AIDS-associated condition. There was an increased incidence of several other forms of cancer, some of which are known to occur at increased rates in transplant recipients who have received immunosuppressive therapy. Improved survival in people with HIV infection may lead to increases in the number that develop these forms of cancer.

Objectives: To estimate the incidence of HIV and hepatitis C virus and risk factors for seroconversion among a cohort of injecting drug users., Design: Retrospective cohort study., Setting: Primary healthcare facility in central Sydney., Subjects: Injecting drug users tested for HIV-1 antibody (n=1179) and antibodies to hepatitis C virus (n=1078) from February 1992 to October 1995., Main Outcome Measures: Incidence of HIV-1 and hepatitis C virus among seronegative subjects who injected drugs and underwent repeat testing. Demographic and behavioural risk factors for hepatitis seroconversion., Results: Incidence of HIV-1 among 426 initially seronegative injecting drug users was 0.17/100 person years (two seroconversions) compared with an incidence of hepatitis C virus of 20.9/100 person years (31 seroconversions) among 152 injecting drug users initially negative for hepatitis C virus. Incidence of hepatitis C virus among injecting drug users aged less than 20 years was 75.6/100 person years. Independent risk factors for hepatitis C virus seroconversion were age less than 20 years and a history of imprisonment., Conclusions: In a setting where prevention measures have contributed to the maintenance of low prevalence and incidence of HIV-1, transmission of hepatitis C virus continues at extremely high levels, particularly among young injecting drug users.

Objectives: To examine the incidence of herpes zoster in HIV-1 infection. To assess the prognostic significance of the occurrence of herpes zoster and progression to AIDS or death, Design and Methods: 146 homosexually active men with known times of HIV-1 seroconversion were identified through the Sydney AIDS Prospective Study and the clinic records of a private medical practice with large caseload of HIV infected homosexual men. Medical records were reviewed for a history of herpes zoster, CD4+ lymphocyte counts, and HIV-1 disease status. Cox's proportional hazards model was used to determine whether herpes zoster predicted progression to AIDS or death., Results: After a mean follow up of 54 months, 30 men (20%) had an episode of herpes zoster and three of these men had one recurrence. The overall incidence of herpes zoster was 44.4 episodes per 1000 person years (95% CI 30.0-63.5). Herpes zoster was not found to be a marker of deteriorating immune functions as measured by CD4+ lymphocyte counts. CD4+ counts did not differ significantly between those with and without zoster at 1 year (551 v 572.10(6)/1, p = 0.79), 2 years (451 v 557, p = 0.11), and 3 years (424 v 481, p = 0.50) following HIV-1 seroconversion. There was no statistically significant difference in progression to AIDS (RR = 1.89, 95% CI 0.80-4.46, p = 0.15) or death (RR = 0.90, 95% CI 0.31-2.65, p = 0.85) from HIV-1 sero-conversion in those who did and those who did not develop herpes zoster., Conclusion: The incidence of herpes zoster was consistent with the findings of other studies. There was no association between the occurrence of herpes zoster and progression of HIV-1 disease.

The purpose of this study was to estimate the incidence of human immunodeficiency virus (HIV) in a cohort of homosexually active men in Sydney. In 1984-85 the Sydney AIDS Prospective Study enrolled homosexually active men, who were followed by six-monthly visits, although regular contact with most participants ceased in the early 1990s. In 1993-94 a major effort was made to establish the HIV status of all participants who had attended more than once. Of the 1075 men enrolled, 528 (49 per cent) were negative at enrollment and had at least one further documented HIV test. The annual incidence rate of HIV infection was highest in the early years of the study, 1984 (9.6 per cent) and 1986 (5.0 per cent), and remained low from 1987 (1.9 per cent) to 1994 (0.0 per cent). The incidence of HIV infection was higher among men aged under 34 years at enrollment and men who reported more than four sexual partners in the six months before enrollment, but these associations disappeared by 1987. The decrease in HIV incidence is consistent with findings from other cohorts followed for this length of time.

Trends in sexual behavior associated with incident infection with human immunodeficiency virus (HIV) type 1 are described and a case-control study was conducted to examine risk factors for HIV seroconversion in homosexual men who became infected with HIV between 1982 and 1994 from four geographic sites: Amsterdam, the Netherlands; San Francisco, California; Vancouver, Canada; and Sydney, Australia. Changes in sexual behaviors were evaluated from cohort visits in the preseroconversion, seroconversion, and postseroconversion intervals and were further examined over three time periods: 1982-1984, 1985-1987, and 1988-1994. In a case-control study, sexual behaviors, substance use, and presence of sexually transmitted disease were compared between 345 HIV-positive cases and 345 seronegative controls matched by visit date and site. Receptive anal intercourse was the sexual behavior most highly associated with seroconversion. The odds ratio (OR) per receptive anal intercourse partner increase was 1.05 (95% confidence interval (CI) 1.02-1.09). To more carefully examine risk associated with receptive oral intercourse, analyses were done in a subgroup of men who reported no or one receptive anal intercourse partner. The risk (OR) associated with receptive oral intercourse partner increase was 1.05 (95% CI 1.0-1.11). In multivariate conditional logistic regression analyses, presence of sexually transmitted disease (OR = 3.39, 95% CI 1.95-5.91) and amphetamine use (OR = 2.55, 95% CI 1.26-5.15) were independently associated with seroconversion. Although the prevalence of major risk factors has decreased over time, the associations of these behaviors and HIV infection persist, suggesting that these risk behaviors remain important avenues for public health interventions.

Objective: To investigate a possible outbreak of tuberculosis in an outpatient HIV treatment facility in Sydney, Australia., Design: Following the diagnosis of pulmonary tuberculosis in an attendee, a prospective screening program was instituted to investigate the potential outbreak., Methods: Screening of 89 potentially exposed patients included chest radiographs (n = 89), and sputum examination (n = 37) over a period of 23 weeks., Results: No cases of tuberculosis were detected by the screening program. However, three (3.4%) of this cohort developed pulmonary tuberculosis between 8 and 10 weeks following diagnosis of the index case. The incidence of active tuberculosis during the following-up period (median, 7.4 months) was 5.3 per 100 person years and represents the lower limit of possible tuberculous infection, as both latent infection, and undiagnosed tuberculosis among those who died could not be excluded. Mycobacterium tuberculosis strains isolated from the index case and three subsequent cases were found to be identical by DNA typing., Conclusion: Nosocomial transmission of tuberculosis in an outpatient treatment setting has been demonstrated. The risk of nosocomial transmission of tuberculosis is significant in institutions caring for HIV-infected patients even in countries with a low prevalence of tuberculosis infection, and highlights the importance of adherence to tuberculosis control guidelines.

The basis of HIV exposure category classification was investigated among selected cases of newly diagnosed HIV infection. Questionnaires seeking specific information on patient-reported exposure to HIV were forwarded to doctors who had requested the HIV antibody test for patients who met the study sample criteria. The cases of interest were those newly diagnosed between 1 January and 31 October 1991 and notified to state and territory health authorities as having been attributed to exposures to HIV other than male homosexual contact or receipt of blood, blood products or tissue. A total of 158 questionnaires was forwarded and 59 per cent were returned. Among the returned questionnaires included in the study sample, exposure to HIV on the original notification to the health authority was given as injecting drug use (8 per cent, 3 of 37), heterosexual contact (46 per cent, 17 of 37), or unavailable (46 per cent, 17 of 37). A clear basis for HIV exposure category classification was provided on the questionnaires for 70 per cent (7 of 10) of cases among women, whereas among men whose infection was attributed to heterosexual contact, a basis for exposure category classification was specified for only 43 per cent (10 of 23) of cases. Although the study was limited by the low response rate, use of the questionnaire provided a relatively simple means for assessing self-reported HIV exposure history.

Twenty-six cases of Kaposi's sarcoma (KS) were recorded by the New South Wales Central Cancer Registry between 1972 and 1982, prior to the first AIDS diagnoses in Australia. The overall annual incidence was 0.47 per million. Incidence was three times higher in males. The highest incidence was in people born in the Middle East and in males born in southern and eastern Europe.