The cascade of care for hepatitis C in Victoria, Australia: a data linkage cohort study.

BACKGROUND: Highly effective hepatitis C therapies are available in Australia. However, people living with hepatitis C face various barriers to accessing care and treatment. AIMS: To identify gaps in the cascade of care for hepatitis C and generate estimates of the number living with untreated infection according to population group, using a representative longitudinal study population. METHODS: We linked hepatitis C notification data from Victoria to national pathology, prescribing and death registry data. We assessed receipt of key clinical services in a large cohort who tested positive for hepatitis C from 1 January 2000 to 31 December 2016, with follow-up to 30 June 2018. We estimated the number still living with hepatitis C, adjusting for spontaneous clearance and mortality. RESULTS: The cohort comprised 45 391 people positive for hepatitis C. Of these, 13 346 (29%) received treatment and an estimated 28% (95% confidence interval (CI): 26-30%) were still living with chronic infection at 30 June 2018, with the remainder still living following spontaneous clearance (30%, 95% CI: 29-32%) or having died (12%, 95% CI: 12-12%). Half (50%) of those still living with hepatitis C were born from 1965 to 1980, and 74% first tested positive before 2011. CONCLUSIONS: Despite an enabling policy environment and subsidised therapy, many people in this cohort were not treated. Increased measures may be needed to engage people in care, including those who acquired hepatitis C more than 10 years ago.

Intra- and interhost genomic diversity of monkeypox virus.

The impact and frequency of infectious disease outbreaks demonstrate the need for timely genomic surveillance to inform public health responses. In the largest known outbreak of mpox, genomic surveillance efforts have primarily focused on high-incidence nations in Europe and the Americas, with a paucity of data from South-East Asia and the Western Pacific. Here we analyzed 102 monkeypox virus (MPXV) genomes sampled from 56 individuals in Melbourne, Australia. All genomes fell within the 2022 MPXV outbreak lineage (B.1), with likely onward local transmission detected. We observed within-host diversity and instances of co-infection, and highlight further examples of structural variation and apolipoprotein B editing complex-driven micro-evolution in the current MPXV outbreak. Updating our understanding of MPXV emergence and diversification will inform public health measures and enable monitoring of the virus' evolutionary trajectory throughout the mpox outbreak.

Incidence of Invasive Pneumococcal Disease Higher Among People Notified With Markers of Hepatitis C Virus Infection: Population-based Surveillance in Victoria, Australia, 2001-2017.

BACKGROUND: Worse outcomes from invasive pneumococcal disease (IPD) have been reported among those coinfected with hepatitis C. We aimed to establish if IPD notification rates are higher among people notified with markers of hepatitis C virus infection than the general population. METHODS: IPD cases notified in Victoria, Australia, from July 2001-December 2017 were linked with hepatitis C cases (diagnosed by serology or PCR testing) notified from January 1991-December 2017. IPD incidence was calculated using population data and the estimated number of Victorians with hepatitis C. RESULTS: From July 2001-December 2017, 6407 IPD cases were notified. Hepatitis C infection was notified in 342 (5.3%) of IPD cases overall, and 24.4% among IPD cases aged 45-49 years. Among IPD cases also notified with hepatitis C, 55.3% were infected with 13-valent pneumococcal conjugate vaccine serotypes and 82.8% with 23-valent pneumococcal polysaccharide vaccine serotypes. Compared with IPD cases without hepatitis C, IPD cases also notified with hepatitis C were younger (mean age, 45.7 vs 49.4 years; P = .011) and more often male (65.5% vs 55.5%, P < .001). Annual IPD notification incidence was 6.8/100 000 among people without hepatitis C and 39.4/100 000 among people with hepatitis C (IRR, 5.8; 95% CI, 5.2-6.4; P < .001). CONCLUSIONS: IPD notification incidence was 5 times higher among people notified with markers of hepatitis C than the general population. Pneumococcal vaccination should be offered to people with markers of hepatitis C virus infection. To facilitate appropriate treatment, young and middle-aged adults with IPD should be tested for hepatitis C.

Spatial and Temporal Epidemiology of Infectious Syphilis in Victoria, Australia, 2015-2018.

ABSTRACT: This analysis of notified syphilis cases in Victoria, Australia between 2015 and 2018 shows that the syphilis epidemic in Victoria has become more generalized, with increases among heterosexual men and women residing in outer Melbourne suburbs-areas that differ from those of gay men.

Epidemiology and phylogenetic analysis of hepatitis D virus infection in Australia.

BACKGROUND: The incidence and trends of the hepatitis D virus (HDV) in Australia have not been recently assessed, and the circulating genotypes have never been determined. AIM: To characterise the current virology and epidemiology of HDV. METHODS: Notifiable disease surveillance and laboratory testing data were analysed to assess demographics, risk factors and trends. HDV serology and RNA testing were performed on requested samples from 2010 to 2016. Sequencing of a 500-nucleotide amplicon of the delta antigen and phylogenetic analysis of the strains from 2009 to 2016 were also conducted. RESULTS: Ninety HDV notifications were reported to the Victorian Department of Health and Human Services between 2010 and 2016. The majority (64.4%) of those diagnosed were born overseas, most commonly in Sudan, Pakistan and Vietnam. Over the same period, 190 patients tested positive for anti-HDV serology and 166 for HDV RNA. Sequencing of isolates from 169 individuals between 2009 and 2016 found that 80.5% strains were genotype 1, 16% genotype 5 and 3.5% genotype 2. Phylogenetic analysis confirmed the relatedness of strains from birth country, demonstrated the presence of the 'Pacific Island' genotype 1 strain in Queensland and supported possible transmission in correctional facilities and within families. CONCLUSIONS: This study demonstrates the ongoing need for routine HDV screening and engagement in clinical care for people living with HBV in Australia. Epidemiological findings highlight the diversity in those affected and provide insights into local and global geographic distribution and transmission patterns.

Aiming for 90-90-90 - the importance of understanding the risk factors for HIV exposure and advanced HIV infection in migrant populations and other groups who do not report male-to-male sex.

Background In Australia, new HIV diagnoses increasingly occur among people who do not report male-to-male sex. Among migrants, it is not clear what proportion acquired infection before migration. Similarly, among Australian-born people, it is not clear what proportion acquired infection in-country. There is a need to better understand the epidemiology of HIV in people who do not report male-to-male sex. METHODS: Victorian public health surveillance data were used to classify migrants as having likely acquired HIV before or after arrival to Australia using a CD4 cell count decline method to estimate date of infection. Place of exposure for Australian-born people was estimated based on self-report. Factors associated with place of HIV acquisition, advanced infection and newly acquired infection were explored among migrants and among Australian-born people. RESULTS: Between July 1996 and June 2014, there were 821 new non-MSM HIV diagnoses. Most (58%) were migrants, and of these, half (54%) were estimated to have acquired HIV before migration. Among Australian-born people, 27% reported exposure likely occurring abroad; the majority of these were men who reported exposure in South-East Asia. Advanced infection was common in migrants (45%) and Australian-born people (35%). Among migrants, birth in South-East Asia was associated with increased odds of advanced infection. CONCLUSION: These results highlight the potential vulnerability of migrants after arrival in Australia, especially those from South-East Asia and Sub-Saharan Africa, and that of Australian-born men travelling to these regions. Public health practice must be strengthened to meet prevention needs of these populations in line with Australian policy.

A positive association between cryptosporidiosis notifications and ambient temperature, Victoria, Australia, 2001-2009.

Increased temperatures provide optimal conditions for pathogen survival, virulence and replication as well as increased opportunities for human-pathogen interaction. This paper examined the relationship between notifications of cryptosporidiosis and temperature in metropolitan and rural areas of Victoria, Australia between 2001 and 2009. A negative binomial regression model was used to analyse monthly average maximum and minimum temperatures, rainfall and the monthly count of cryptosporidiosis notifications. In the metropolitan area, a 1 °C increase in monthly average minimum temperature of the current month was associated with a 22% increase in cryptosporidiosis notifications (incident rate ratio (IRR) 1.22; 95% confidence interval (CI) 1.13-1.31). In the rural area, a 1 °C increase in monthly average minimum temperature, lagged by 3 months, was associated with a 9% decrease in cryptosporidiosis notifications (IRR 0.91; 95% CI 0.86-0.97). Rainfall was not associated with notifications in either area. These relationships should be considered when planning public health response to ecological risks as well as when developing policies involving climate change. Rising ambient temperature may be an early warning signal for intensifying prevention efforts, including appropriate education for pool users about cryptosporidiosis infection and management, which might become more important as temperatures are projected to increase as a result of climate change.

Trends in HIV testing and HIV stage at diagnosis among people newly diagnosed with HIV.

OBJECTIVE: To identify groups more likely to be referred for HIV testing because of symptomatic presentation rather than as part of asymptomatic screening. DESIGN: A retrospective analysis of Australian National HIV Registry (NHR) surveillance data including sociodemographic and clinical data, as well as reasons for HIV test. METHODS: Using notification records from 2017 to 2022, we summarised reasons for testing leading to an HIV diagnosis. Reasons for testing were combined with clinical status at diagnosis to derive HIV testing categories: testing while symptomatic; asymptomatic HIV screening; seroconversion; and other test reason. We stratified these categories by stage of HIV at diagnosis with late-stage HIV defined as a CD4 count <350 cells/µL at time of diagnosis. RESULTS: Among 4,134 HIV notifications with at least one reason for testing recorded, STI screening was the predominant reason for test referral (38%), followed by HIV indicative symptoms (31%), and risk behaviour (13%). By testing category, people aged 50 years or older (24%), people with HIV attributed to heterosexual sex (21%), people born in Sub-Saharan Africa (19%), and women (17%) had lower levels of asymptomatic screening. More late-stage HIV diagnoses resulted from testing while symptomatic (58%) compared with asymptomatic screening (25%). CONCLUSIONS: Older people and heterosexuals may not access HIV focused healthcare where HIV screening is routinely offered. Instead, HIV testing opportunities may arise in other settings. By normalising HIV testing and offering low-cost HIV screening in a range of settings, it may be possible to facilitate earlier HIV diagnoses, better health outcomes, and reduced onward transmission.

Characterising HIV-1 transmission in Victoria, Australia: a molecular epidemiological study.

Background: In Australia the incidence of HIV has declined steadily, yet sustained reduction of HIV transmission in this setting requires improved public health responses. As enhanced public health responses and prioritisation of resources may be guided by molecular epidemiological data, here we aimed to assess the applicability of these approaches in Victoria, Australia. Methods: A comprehensive collection of HIV-1 pol sequences from individuals diagnosed with HIV in Victoria, Australia, between January 1st 2000 and December 31st 2020 were deidentified and used as the basis of our assessment. These sequences were subtyped and surveillance drug resistance mutations (SDRMs) identified, before definition of transmission groups was performed using HIV-TRACE (0.4.4). Phylodynamic methods were applied using BEAST (2.6.6), assessing effective reproductive numbers for large groups, and additional demographic data were integrated to provide a high resolution view of HIV transmission in Victoria on a decadal time scale. Findings: Based on standard settings for HIV-TRACE, 70% (2438/3507) of analysed HIV-1 pol sequences were readily assigned to a transmission group. Individuals in transmission groups were more commonly males (aOR 1.50), those born in Australia (aOR 2.13), those with probable place of acquisition as Victoria (aOR 6.73), and/or those reporting injectable drug use (aOR 2.13). SDRMs were identified in 375 patients (10.7%), with sustained transmission of these limited to a subset of smaller groups. Informative patterns of epidemic growth, stabilisation, and decline were observed; many transmission groups showed effective reproductive numbers (R e ) values reaching greater than 4.0, representing considerable epidemic growth, while others maintained low R e values. Interpretation: This study provides a high resolution view of HIV transmission in Victoria, Australia, and highlights the potential of molecular epidemiology to guide and enhance public health responses in this setting. This informs ongoing discussions with community groups on the acceptability and place of molecular epidemiological approaches in Australia. Funding: National Health and Medical Research Council, Australian Research Council.

Characterisation of Treponema pallidum lineages within the contemporary syphilis outbreak in Australia: a genomic epidemiological analysis.

BACKGROUND: The incidence of syphilis has increased markedly in the past decade in high-income countries, including Australia. To date, however, genomic studies of Treponema pallidum have focused mainly on the northern hemisphere. Here, we aimed to characterise the lineages of T pallidum driving the current syphilis epidemic in Australia. METHODS: In this genomic epidemiological analysis, using phylogenomic and phylodynamic analyses, we analysed 456 high-quality T pallidum genomes collected from clinical samples in Australia between Oct 19, 2005, and Dec 31, 2020, and contextualised this information with publicly available sequence data. We also performed detailed genomic characterisation of putative antimicrobial resistance determinants, in addition to correlating single-locus typing of the TP0548 allele with the T pallidum phylogeny. FINDINGS: Phylogenomic analyses identified four major sublineages circulating in Australia and globally, two belonging to the SS14 lineage, and two belonging to the Nichols lineage. Australian sublineages were further delineated into twelve subgroups, with five of the six largest subgroups associated with men who have sex with men, and the sixth lineage was predominantly associated with heterosexual people. Most Australian T pallidum genomes (398 [87%] of 456) were genotypically macrolide resistant, and TP0548 typing correlated significantly with T pallidum genomic subgroups. INTERPRETATION: These findings show that the current syphilis epidemic in Australia is driven by multiple lineages of T pallidum, rather than one distinct outbreak. Major subgroups of T pallidum in Australia have emerged within the past 30 years, are closely related to global lineages, and circulate across different sexual networks. In conjunction with improved testing and treatment, these data could better inform the control of syphilis in Australia. FUNDING: National Health and Medical Research Council, Australian Research Council.

Intrahousehold transmission of pandemic (H1N1) 2009 virus, Victoria, Australia.

To examine intrahousehold secondary transmission of pandemic (H1N1) 2009 virus in households in Victoria, Australia, we conducted a retrospective cross-sectional study in late 2009. We randomly selected case-patients reported during May-June 2009 and their household contacts. Information collected included household characteristics, use of prevention and control measures, and signs and symptoms. Secondary cases were defined as influenza-like illness in household contacts within the specified period. Secondary transmission was identified for 18 of 122 susceptible household contacts. To identify independent predictors of secondary transmission, we developed a model. Risk factors were concurrent quarantine with the household index case-patient, and a protective factor was antiviral prophylaxis. These findings show that timely provision of antiviral prophylaxis to household contacts, particularly when household members are concurrently quarantined during implementation of pandemic management strategies, delays or contains community transmission of pandemic (H1N1) 2009 virus.

Epidemiology of chronic hepatitis B and C in Victoria, Australia: insights and impacts from enhanced surveillance.

OBJECTIVE: To assess the impact of an enhanced viral hepatitis surveillance program on data completeness and on epidemiological assessment of affected populations. METHODS: Notified cases of non-acute hepatitis B and C were analysed to determine demographic characteristics and risk factors during the period prior to July 2015-June 2016, and during enhanced surveillance of the period July 2016-June 2017, during which time doctors were contacted for information about new diagnoses. RESULTS: During the enhanced period, completeness for country of birth and Indigenous status doubled for both hepatitis B and hepatitis C, from 18-37% to 48-65%. The incidence ratio of hepatitis C among Aboriginal and Torres Strait Islander people increased from eight-fold to 11.4-fold, and the proportion of hepatitis B cases reported as born in China and Vietnam relative to other countries increased. New data fields identified that 12% of hepatitis C diagnoses occurred in a correctional facility, and 2% of hepatitis B cases were healthcare workers. CONCLUSIONS: Improved data completeness highlighted the underlying epidemiology of chronic viral hepatitis, demonstrating the increased burden of infection among specific priority populations. Implications for public health: Enhanced surveillance provides greater insight into the epidemiology of chronic viral hepatitis, identifying groups at risk and opportunities for public health action.

Phylogenetic clustering networks among heterosexual migrants with new HIV diagnoses post-migration in Australia.

BACKGROUND: It is estimated that approximately half of new HIV diagnoses among heterosexual migrants in Victoria, Australia, were acquired post-migration. We investigated the characteristics of phylogenetic clusters in notified cases of HIV among heterosexual migrants. METHODS: Partial HIV pol sequences obtained from routine clinical genotype tests were linked to Victorian HIV notifications with the following exposures listed on the notification form: heterosexual sexual contact, injecting drug use, bisexual sexual contact, male-to male sexual contact or heterosexual sexual contact in combination with injecting drug use, unknown exposure. Those with heterosexual sexual contact as the only exposure were the focus of this study, with the other exposures included to better understand transmission networks. Additional reference sequences were extracted from the Los Alamos database. Maximum likelihood methods were used to infer the phylogeny and the robustness of the resulting tree was assessed using bootstrap analysis. Phylogenetic clusters were defined on the basis of bootstrap and genetic distance. RESULTS: HIV pol sequences were available for 332 of 445 HIV notifications attributed to only heterosexual sexual contact in Victoria from 2005-2014. Forty-three phylogenetic clusters containing at least one heterosexual migrant were detected, 30 (70%) of which were pairs. The characteristics of these phylogenetic clusters varied considerably by cluster size. Pairs were more likely to be composed of people living with HIV from a single country of birth (p = 0.032). Larger clusters (n≥3) were more likely to contain people born in Australian/New Zealand (p = 0.002), migrants from more than one country of birth (p = 0.013) and viral subtype-B, the most common subtype in Australia (p = 0.006). Pairs were significantly more likely to contain females (p = 0.037) and less likely to include HIV diagnoses with male-to-male sexual contact reported as a possible exposure (p<0.001) compared to larger clusters (n≥3). CONCLUSION: Migrants appear to be at elevated risk of HIV acquisition, in part due to intimate relationships between migrants from the same country of origin, and in part due to risks associated with the broader Australian HIV epidemic. However, there was no evidence of large transmission clusters driven by heterosexual transmission between migrants. A multipronged approach to prevention of HIV among migrants is warranted.

Trends in late and advanced HIV diagnoses among migrants in Australia; implications for progress on Fast-Track targets: A retrospective observational study.

Achieving the Joint United Nations Program on human immunodeficiency virus (HIV)/AIDS Fast-Track targets requires additional strategies for mobile populations. We examined trends and socio-demographics of migrants (overseas-born) and Australian-born individuals presenting with late and advanced HIV diagnoses between 2008 and 2017 to help inform public health approaches for HIV testing coverage and linkage to care and treatment.We conducted a retrospective population-level observational study of individuals diagnosed with HIV in Australia and reported to the National HIV Registry. Annual proportional trends in late (CD4+ T-cell count <350 cells/µL) and advanced (CD4+ T-cell count <200 cells/µL). HIV diagnoses were determined using Poisson regression.Of 9926 new HIV diagnoses from 2008 to 2017, 84% (n = 8340) were included in analysis. Overall, 39% (n = 3267) of diagnoses were classified as late; 52% (n = 1688) of late diagnoses were advanced. Of 3317 diagnoses among migrants, 47% were late, versus 34% of Australian-born diagnoses (P < .001).The annual proportions of late (incidence rate ratio [IRR] 1.00; 95% confidence interval [CI] 0.99-1.01) and advanced HIV diagnoses (IRR 1.01; 95% CI 0.99-1.02) remained constant. Among migrants with late HIV diagnosis, the proportion reporting male-to-male sex exposure (IRR 1.05; 95% CI 1.03-1.08), non-English speaking (IRR 1.03; 95% CI 1.01-1.05), and individuals born in countries in low HIV-prevalence (IRR 1.02; 95% CI 1.00-1.04) increased. However, declines were noted among some migrants' categories such as females, heterosexual exposure, English speaking, and those born in high HIV-prevalence countries.Late HIV diagnosis remains a significant public health concern in Australia. Small declines in late diagnosis among some migrant categories are offset by increases among male-to-male exposures. Reaching the Fast-Track targets in Australia will require targeted testing and linkage to care strategies for all migrant populations, especially men who have sex with men.

Two decades of surveillance data show late presentation among a diverse group of women diagnosed with HIV in Victoria, Australia.

OBJECTIVE: To develop an HIV response suited to women and to inform appropriate services, we describe the characteristics of women diagnosed and living with HIV using 22 years of high-quality surveillance data. METHODS: Data on women newly diagnosed with HIV between 1994 and 2016 and women living with diagnosed HIV in Victoria at 31 December 2016 were extracted from the Victorian Public Health Surveillance System. Descriptive analysis by place of birth was performed and Poisson regression used to assess trends over time. RESULTS: There were 465 new diagnoses among women in Victoria between 1994 and 2016 and 613 women living with HIV in 2016. Women were diagnosed late, and frequently reported no HIV testing history, AIDS-defining illness or other symptoms of HIV at diagnosis. These indicators of delayed diagnosis were even greater for non-Australian-born women. Conclusions and implications for public health: For Victoria to reach the ambitious targets for diagnosis, treatment and viral suppression in 95% of people living with HIV, prevention programs and efforts to increase early diagnosis as well as support services must consider the epidemiology and diversity of women.

Bridging of Neisseria gonorrhoeae lineages across sexual networks in the HIV pre-exposure prophylaxis era.

Whole genome sequencing (WGS) has been used to investigate transmission of Neisseria gonorrhoeae, but to date, most studies have not combined genomic data with detailed information on sexual behaviour to define the extent of transmission across population risk groups (bridging). Here, through combined epidemiological and genomic analysis of 2,186N. gonorrhoeae isolates from Australia, we show widespread transmission of N. gonorrhoeae within and between population groups. We describe distinct transmission clusters associated with men who have sex with men (MSM) and heterosexuals, and men who have sex with men and women (MSMW) are identified as a possible bridging population between these groups. Further, the study identifies transmission of N. gonorrhoeae between HIV-positive and HIV-negative individuals receiving pre-exposure prophylaxis (PrEP). Our data highlight several groups that can be targeted for interventions aimed at improving gonorrhoea control, including returning travellers, sex workers, and PrEP users.

Epidemiology of gonorrhoea notifications in Australia, 2007-12.

UNLABELLED: Background An increase in the notification rate of gonorrhoea was observed in the national surveillance system. In Australia, gonorrhoea is relatively rare, apart from among some populations of Aboriginal people and men who have sex with men. METHODS: Data about gonorrhoea cases reported between 2007 and 2012 from all Australian jurisdictions were extracted from the National Notifiable Diseases Surveillance System. Analyses were undertaken of the time trends in counts and rates, according to jurisdiction, gender, Aboriginal and Torres Strait Islander status, diagnosis method and sexual orientation. RESULTS: The largest increase in notifications between 2007 and 2012 was observed in both men and women in New South Wales (2.9- and 3.7-fold greater in 2012 than 2007, respectively) and Victoria (2.4- and 2.7-fold greater in 2012 than 2007, respectively), men in the Australian Capital Territory and women in Queensland. The highest notification rates remained in Indigenous people in the Northern Territory and Western Australia, and particularly in women, although rates may have decreased over the study period. Changes in age and sex distribution, antimicrobial resistance and patterns of exposure and acquisition were negligible. CONCLUSIONS: There is an ongoing gonorrhoea epidemic affecting Aboriginal and Torres Strait Islander people in Australia, but the increases in notifications have occurred primarily in non-Aboriginal populations in the larger jurisdictions. Interpretation of these surveillance data, especially in relation to changes in population subgroups, would be enhanced by laboratory testing data. Further efforts are needed to decrease infection rates in populations at highest risk.

The spread of influenza A(H1N1)pdm09 in Victorian school children in 2009: implications for revised pandemic planning.

BACKGROUND: Victoria was the first state in Australia to experience community transmission of influenza A(H1N1)pdm09. We undertook a descriptive epidemiological analysis of the first 1,000 notified cases to describe the epidemic associated with school children and explore implications for school closure and antiviral distribution policy in revised pandemic plans. METHODS: Records of the first 1,000 laboratory-confirmed cases of influenza A(H1N1)pdm09 notified to the Victorian Government Department of Health between 20 May and 5 June 2009 were extracted from the state's notifiable infectious diseases database. Descriptive analyses were conducted on case demographics, symptoms, case treatment, prophylaxis of contacts and distribution of cases in schools. RESULTS: Two-thirds of the first 1,000 cases were school-aged (5-17 years) with cases in 203 schools, particularly along the north and western peripheries of the metropolitan area. Cases in one school accounted for nearly 8% of all cases but the school was not closed until nine days after symptom onset of the first identified case. Amongst all cases, cough (85%) was the most commonly reported symptom followed by fever (68%) although this was significantly higher in primary school children (76%). The risk of hospitalisation was 2%. The median time between illness onset and notification of laboratory confirmation was four days, with only 10% of cases notified within two days of onset and thus eligible for oseltamivir treatment. Nearly 6,000 contacts were followed up for prophylaxis. CONCLUSIONS: With a generally mild clinical course and widespread transmission before its detection, limited and short-term school closures appeared to have minimal impact on influenza A(H1N1)pdm09 transmission. Antiviral treatment could rarely be delivered to cases within 48 hours of symptom onset. These scenarios and lessons learned from them need to be incorporated into revisions of pandemic plans.

The changing age distribution of men who have sex with men diagnosed with HIV in Victoria.

OBJECTIVE: To describe recent trends among men who have sex with men (MSM) in age at diagnosis of HIV in Victoria. DESIGN AND SETTING: Analysis of Victorian HIV surveillance data from (i) passive surveillance (2000-2009) and (ii) the Victorian Primary Care Network for Sentinel Surveillance (VPCNSS) (2006-2009). Age-trend comparisons were made using syphilis and gonorrhoea enhanced surveillance. MAIN OUTCOME MEASURES: HIV diagnoses, HIV testing and behavioural indicators by year and age group among MSM. RESULTS: Following a period of sustained increase between 2000 and 2007, the median age at HIV diagnosis among MSM declined significantly, from 38.8 years in 2007 to 35.3 years in 2008 (P=0.023), remaining at 35.9 years in 2009. Between 2007 and 2008, the median age of syphilis and gonorrhoea notifications also declined, from 40.6 to 36.0 years and from 32.3 to 29.3 years, respectively. The median age of HIV testing among MSM in the VPCNSS population remained constant between 2006 and 2009, at 33.0 years. Compared with older MSM, those aged less than 35 years were more likely to have never previously been tested for HIV (relative risk [RR], 1.36 [95% CI, 1.30-1.41]); to not know the HIV status of their regular partner (RR, 1.11 [95% CI, 1.01-1.21]); and to report inconsistent condom use with casual partners (RR, 1.07 [95% CI, 1.01-1.14]) and regular partners (RR, 1.07 [95% CI, 1.00-1.14]). CONCLUSIONS: Younger MSM in Victoria may be at increasing risk of HIV infection. Enhanced methods of monitoring HIV and sexually transmitted infection transmission in younger MSM are needed, as well as prevention messages to target this group, who may not fully understand their HIV risk.

Enhanced case detection for newly acquired hepatitis C infection: epidemiological findings and health service implications.

Identifying newly acquired hepatitis C infections and describing their epidemiological characteristics has public health importance but can be resource intensive. We developed a new approach to conducting surveillance for newly acquired hepatitis C infection and analysed the epidemiological findings and health service implications. Doctors and laboratories in the Australian state of Victoria are required by law to notify all hepatitis C diagnoses to the Department of Human Services, but the routine report is limited to basic demographic information. For all cases reported as being aged 16-19 years or having clinical or laboratory indicators of newly acquired infection, during the period July 2004 to December 2005, additional information was sought from diagnosing doctors and used to classify cases as 'newly acquired' or 'unspecified' using a standard case definition. Of the 4,561 hepatitis C notifications received by the Department during the study period, 415 (9%) were selected for follow up and 148 of these (36%) were classified as newly acquired infections, compared with 4%-10% achieved from previous systems. Based on the enhanced data collection, the most common risk factor for transmission among newly acquired infections was injecting drug use (86%), the median age was 23 years, 59% were males and the predominant reason for testing was drug and alcohol screening (32%). This surveillance system was much more efficient at detecting newly acquired cases of hepatitis C infection than other approaches used in Victoria. Initial results show that injecting drug use continues to be by far the predominant mode of hepatitis C transmission in Victoria.