Infectious syphilis in women and heterosexual men in major Australian cities: sentinel surveillance data, 2011-2019.

OBJECTIVES: To examine changes in the positive infectious syphilis test rate among women and heterosexual men in major Australian cities, and rate differences by social, biomedical, and behavioural determinants of health. DESIGN, SETTING: Analysis of data extracted from de-identified patient records from 34 sexual health clinics participating in the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance of Sexually Transmissible Infections and Blood Borne Viruses (ACCESS). PARTICIPANTS: First tests during calendar year for women and heterosexual men aged 15 years or more in major cities who attended ACCESS sexual health clinics during 2011-2019. MAIN OUTCOME MEASURES: Positive infectious syphilis test rate; change in annual positive test rate. RESULTS: 180 of 52 221 tested women (0.34%) and 239 of 36 341 heterosexual men (0.66%) were diagnosed with infectious syphilis. The positive test rate for women was 1.8 (95% confidence interval [CI], 0.9-3.2) per 1000 tests in 2011, 3.0 (95% CI, 2.0-4.2) per 1000 tests in 2019 (change per year: rate ratio [RR], 1.12; 95% CI, 1.01-1.25); for heterosexual men it was 6.1 (95% CI, 3.8-9.2) per 1000 tests in 2011 and 7.6 (95% CI, 5.6-10) per 1000 tests in 2019 (RR, 1.10; 95% CI, 1.03-1.17). In multivariable analyses, the positive test rate was higher for women (adjusted RR [aRR], 1.85; 95% CI, 1.34-2.55) and heterosexual men (aRR, 2.39; 95% CI, 1.53-3.74) in areas of greatest socio-economic disadvantage than for those in areas of least socio-economic disadvantage. It was also higher for Indigenous women (aRR, 2.39; 95% CI, 1.22-4.70) and for women who reported recent injection drug use (aRR, 4.87; 95% CI, 2.18-10.9) than for other women; it was lower for bisexual than heterosexual women (aRR, 0.48; 95% CI, 0.29-0.81) and for women who reported recent sex work (aRR, 0.35; 95% CI, 0.29-0.44). The positive test rate was higher for heterosexual men aged 40-49 years (aRR, 2.11; 95% CI, 1.42-3.12) or more than 50 years (aRR, 2.36; 95% CI, 1.53-3.65) than for those aged 15-29 years. CONCLUSION: The positive test rate among both urban women and heterosexual men tested was higher in 2019 than in 2011. People who attend reproductive health or alcohol and drug services should be routinely screened for syphilis.

Incomplete recording of Indigenous identification status under-estimates the prevalence of Indigenous population attending Australian general practices: a cross sectional study.

BACKGROUND: Australian Aboriginal and Torres Strait Islander (Indigenous) peoples face major health disadvantage across many conditions. Recording of patients' Indigenous status in general practice records supports equitable delivery of effective clinical services. National policy and accreditation standards mandate recording of Indigenous status in patient records, however for a large proportion of general practice patient records it remains incomplete. We assessed the completeness of Indigenous status in general practice patient records, and compared the patient self-reported Indigenous status to general practice medical records. METHODS: A cross sectional analysis of Indigenous status recorded at 95 Australian general practices, participating in the Australian Chlamydia Control Effectiveness Pilot (ACCEPt) in 2011. Demographic data were collected from medical records and patient surveys from 16 to 29 year old patients at general practices, and population composition from the 2011 Australian census. General practitioners (GPs) at the same practices were also surveyed. Completeness of Indigenous status in general practice patient records was measured with a 75% benchmark used in accreditation standards. Indigenous population composition from a patient self-reported survey was compared to Indigenous population composition in general practice records, and Australian census data. RESULTS: Indigenous status was complete in 56% (median 60%, IQR 7-81%) of general practice records for 109,970 patients aged 16-29 years, and Indigenous status was complete for 92.5% of the 3355 patients aged 16-29 years who completed the survey at the same clinics. The median proportion per clinic of patients identified as Indigenous was 0.9%, lower than the 1.8% from the patient surveys and the 1.7% in clinic postcodes (ABS). Correlations between the proportion of Indigenous people self-reporting in the patient survey (5.2%) compared to status recorded in all patient records (2.1%) showed a fair association (r = 0.6468; p < 0.01). After excluding unknown /missing data, correlations weakened. CONCLUSIONS: Incomplete Indigenous status records may under-estimate the true proportion of Indigenous people attending clinics but have higher association with self-reported status than estimates which exclude missing/unknown data. The reasons for incomplete Indigenous status recording in general practice should be explored so efforts to improve recording can be targeted and strengthened. TRIAL REGISTRATION: ACTRN12610000297022 . Registered 13th April 2010.

Trends in the prevalence of hepatitis B infection among women giving birth in New South Wales.

OBJECTIVES: To evaluate the effect of targeted and catch-up hepatitis B virus (HBV) vaccination programs in New South Wales on HBV prevalence among women giving birth for the first time. DESIGN: Observational study linking data from the NSW Perinatal Data Collection for women giving birth during 2000-2012 with HBV notifications in the NSW Notifiable Conditions Information Management System. MAIN OUTCOME MEASURES: HBV prevalence in Indigenous Australian, non-Indigenous Australian-born, and overseas-born women giving birth. RESULTS: Of 482 944 women who gave birth to their first child, 3383 (0.70%) were linked to an HBV notification. HBV prevalence was 1.95% (95% CI, 1.88-2.02%) among overseas-born women, 0.79% (95% CI, 0.63-0.95%) among Indigenous Australian women, and 0.11% (95% CI, 0.09-0.12%) among non-Indigenous Australian-born women. In Indigenous Australian women, prevalence was significantly lower for those who had been eligible for inclusion in the targeted at-risk newborn or universal school-based vaccination programs (maternal year of birth, 1992-1999: 0.15%) than for those who were not (born ≤ 1981: 1.31%; for trend, P < 0.001). There was no statistically significant downward trend among non-Indigenous Australian-born or overseas-born women. HBV prevalence was higher among Indigenous women residing in regional and remote areas than those in major cities (adjusted odds ratio [aOR], 2.23; 95% CI, 1.40-3.57), but lower for non-Indigenous (aOR, 0.39; 95% CI, 0.28-0.55) and overseas-born women (aOR, 0.61; 95% CI, 0.49-0.77). CONCLUSION: Among women giving birth, there was a significant reduction in HBV prevalence in Indigenous women associated with the introduction of the HBV vaccination program in NSW, although prevalence remains higher than among non-Indigenous Australian-born women, and it also varies by region of residence. Continuing evaluation is needed to ensure that the prevalence of HBV infections continues to fall in Australia.

Low HIV testing rates among people with a sexually transmissible infection diagnosis in remote Aboriginal communities.

OBJECTIVE: To determine the rates of HIV testing among people who had received positive test results for chlamydia, gonorrhoea and trichomoniasis, or who had been tested for syphilis. DESIGN, SETTING AND PARTICIPANTS: Pathology data for the period January 2010 - December 2014 from 65 remote Aboriginal communities participating in the STRIVE trial of sexually transmissible infection (STI) control were analysed. MAIN OUTCOME MEASURES: Rates of HIV testing within 30 and 90 days of an STI test (for chlamydia, gonorrhoea or trichomoniasis), the result of which was positive, and within 30 days of a test for syphilis; factors independently associated with concurrent HIV testing. RESULTS: 31.8% of 15 260 positive STI test results were linked with an HIV test within 30 days of the test (including 5.6% not on the same day), and 34.8% within 90 days; 44.1% were linked with syphilis testing within 30 days. 53.4% of all those tested for syphilis were also tested for HIV within 30 days. Multivariate analysis found that HIV testing was more likely for men, in geographical regions 3 and 4, in association with positive STI test results during 2012, 2013 or 2014 (v 2010), and in association with positive test results for gonorrhoea or chlamydia. Similar associations with these factors were found for syphilis testing. CONCLUSIONS: A significant challenge in Aboriginal health is avoiding an increase in the number of HIV infections. One critical intervention in this regard is timely and appropriate testing. Adhering to screening recommendations is clearly an aspect of the delivery of sexual health services to remote communities that can be improved in striving to achieve this aim.

Australian trachoma surveillance annual report, 2013.

Australia remains the only developed country to have endemic levels of trachoma (a prevalence of 5% or greater among children) in some regions. Endemic trachoma in Australia is found predominantly in remote and very remote Aboriginal communities. The Australian Government funds the National Trachoma Surveillance and Reporting Unit to collate, analyse and report trachoma prevalence data and document trachoma control strategies in Australia through an annual surveillance report. This report presents data collected in 2013. Data are collected from Aboriginal and Torres Strait Island communities designated at-risk for endemic trachoma within New South Wales, the Northern Territory, South Australia and Western Australia. The World Health Organization grading criteria were used to diagnose cases of trachoma in Aboriginal children, with jurisdictions focusing screening activities on the 5-9 years age group; but some children in the 1-4 and 10-14 years age groups were also screened. The prevalence of trachoma within a community was used to guide treatment strategies as a public health response. Aboriginal adults aged 40 years or over were screened for trichiasis. Screening coverage for the estimated population of children aged 5-9 years and adults aged 40 years or over in at-risk communities required to be screened in 2013 was 84% and 30%, respectively. There was a 4% prevalence of trachoma among children aged 5-9 years who were screened. Of communities screened, 50% were found to have no cases of active trachoma and 33% were found to have endemic levels of trachoma. Treatment was required in 75 at-risk communities screened. Treatment coverage for active cases and their contacts varied between jurisdictions from 79% to 100%. Trichiasis prevalence was 1% within the screened communities.

A sexual health quality improvement program (SHIMMER) triples chlamydia and gonorrhoea testing rates among young people attending Aboriginal primary health care services in Australia.

BACKGROUND: In Australia, chlamydia is the most commonly notifiable infection and over the past ten years chlamydia and gonorrhoea notification rates have increased. Aboriginal compared with non-Aboriginal Australians have the highest notifications rates of chlamydia and gonorrhoea. Regular testing of young people for chlamydia and gonorrhoea is a key prevention strategy to identify asymptomatic infections early, provide treatment and safe sex education. This study evaluated if a sexual health quality improvement program (QIP) known as SHIMMER could increase chlamydia and gonorrhoea testing among young people attending four Aboriginal primary health care services in regional areas of New South Wales, Australia. METHODS: We calculated the proportion of 15-29 year olds tested and tested positivity for chlamydia and gonorrhoea in a 12-month before period (March 2010-February 2011) compared with a 12-month QIP period (March 2012-February 2013). Logistic regression was used to assess the difference in the proportion tested for chlamydia and gonorrhoea between study periods by gender, age group, Aboriginal status and Aboriginal primary health service. Odds ratios (OR) and their 95 % confidence intervals (CIs) were calculated with significance at p < 0.05. RESULTS: In the before period, 9 % of the 1881 individuals were tested for chlamydia, compared to 22 % of the 2259 individuals in the QIP period (OR): 1.43, 95 % CI: 1.22-1.67). From the before period to the QIP period, increases were observed in females (13 % to 25 %, OR: 1.32, 95 % CI: 1.10-1.59) and males (3 % to 17 %, OR: 1.85, 95 % CI: 1.36-2.52). The highest testing rate in the QIP period was in 15-19 year old females (16 % to 29 %, OR: 1.02, 95 % CI: 0.75-1.37), yet the greatest increase was in 20-24 year olds males (3 % to 19 %, OR: 1.65, 95 % CI: 1.01-2.69). Similar increases were seen in gonorrhoea testing. Overall, there were 70 (11 %) chlamydia diagnoses, increasing from 24 in the before to 46 in the QIP period. Overall, 4 (0.7 %) gonorrhoea tests were positive. CONCLUSIONS: The QIP used in SHIMMER almost tripled chlamydia and gonorrhoea testing in young people and found more than twice as many chlamydia infections. The QIP could be used by other primary health care centres to increase testing among young people.

Incidence and predictors of annual chlamydia testing among 15-29 year olds attending Aboriginal primary health care services in New South Wales, Australia.

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.

National trachoma surveillance annual report, 2012.

Australia remains the only developed country to have endemic levels of trachoma (a prevalence of 5% or greater among children) in some regions. Endemic trachoma in Australia is found predominantly in remote and very remote Aboriginal communities. The Australian Government funds a National Trachoma Surveillance and Reporting Unit to collate, analyse and report trachoma prevalence data and document trachoma control strategies in Australia through an annual surveillance report. This report presents data collected in 2012. Data are collected from Aboriginal and Torres Strait communities designated as at-risk for endemic trachoma in the Northern Territory, Queensland, South Australia and Western Australia. The World Health Organization grading criteria were used to diagnose cases of trachoma in Aboriginal children with jurisdictions focusing screening activities on the 5-9 years age group; however, some children in the 1-4 and 10-14 years age groups were also screened. The prevalence of trachoma within a community was used to guide treatment strategies as a public health response. Aboriginal adults aged 40 years or older were screened for trichiasis. Community screening coverage of the designated at-risk communities was 96%. Screening coverage of the estimated population of children aged 5-9 years and adults aged 40 years or older in at-risk communities was 71% and 31%, respectively. Trachoma prevalence among children aged 5-9 years who were screened was 4%. Of communities screened, 63% were found to have no cases of active trachoma and 25% were found to have endemic levels of trachoma. Treatment was required in 87 at-risk communities screened. Treatment coverage of active cases and their contacts varied from 79%-97% between jurisdictions. Trichiasis prevalence was 2% within the screened communities.

High chlamydia positivity rates in Indigenous people attending Australian sexual health services.

OBJECTIVE: To assess the clinical epidemiology of chlamydia among Aboriginal and Torres Strait Islander (Indigenous) people attending sexual health services around Australia. DESIGN: Retrospective analysis of routine demographic, behavioural and clinical data, between 1 January 2006 and 31 December 2011. SETTING: 18 sexual health services in major cities and regional centres in five jurisdictions. MAIN OUTCOME MEASURES: Attendance, chlamydia testing and positivity rates in patients visiting for the first time, and factors associated with chlamydia positivity. RESULTS: Of 168 729 new patients, 7103 (4.2%) identified as Indigenous, of whom 74.3% were tested for chlamydia. Chlamydia positivity was 17.0% in Indigenous women (23.3% in 15-19-year-olds and 18.9% in 20-24-year-olds) and 17.3% in Indigenous men (20.2% in 15-19-year-olds and 24.2% in 20-24-year-olds). There was an increasing trend in chlamydia positivity in Indigenous women from 2006 to 2011 (P for trend = 0.001), but not in Indigenous men. In Indigenous women, factors independently associated with positivity were: younger age, being heterosexual, living in Queensland and attending the service in 2010. In Indigenous men, independent factors associated with chlamydia positivity were younger age, being heterosexual, having sex only in Australia and living in a regional area. CONCLUSION: The high and increasing chlamydia positivity rates highlight the need for enhanced prevention and screening programs for Indigenous people.

Chronic hepatitis B prevalence among Aboriginal and Torres Strait Islander Australians since universal vaccination: a systematic review and meta-analysis.

BACKGROUND: In Australia, higher rates of chronic hepatitis B (HBsAg) have been reported among Aboriginal and Torres Strait Islander (Indigenous) compared with non-Indigenous people. In 2000, the Australian government implemented a universal infant/adolescent hepatitis B vaccination program. We undertook a systematic review and meta-analysis to assess the disparity of HBsAg prevalence between Indigenous and non-Indigenous people, particularly since 2000. METHODS: We searched Medline, Embase and public health bulletins up to March 2011. We used meta-analysis methods to estimate HBsAg prevalence by Indigenous status and time period (before and since 2000). RESULTS: There were 15 HBsAg prevalence estimates (from 12 studies) among Indigenous and non-Indigenous people; adults and pregnant women (n = 9), adolescents (n = 3), prisoners (n = 2), and infants (n = 1). Of these, only one subgroup (adults/pregnant women) involved studies before and since 2000 and formed the basis of the meta-analysis. Before 2000, the pooled HBsAg prevalence estimate was 6.47% (95% CI: 4.56-8.39); 16.72% (95%CI: 7.38-26.06) among Indigenous and 0.36% (95%CI:-0.14-0.86) in non-Indigenous adults/pregnant women. Since 2000, the pooled HBsAg prevalence was 2.25% (95% CI: 1.26-3.23); 3.96% (95%CI: 3.15-4.77) among Indigenous and 0.90% (95% CI: 0.53-1.28) in non-Indigenous adults/pregnant women. CONCLUSIONS: The disparity of HBsAg prevalence between Indigenous and non-Indigenous people has decreased over time; particularly since the HBV vaccination program in 2000. However HBsAg prevalence remains four times higher among Indigenous compared with non-Indigenous people. The findings highlight the need for opportunistic HBV screening of Indigenous people to identify people who would benefit from vaccination or treatment.

Population movement can sustain STI prevalence in remote Australian indigenous communities.

BACKGROUND: For almost two decades, chlamydia and gonorrhoea diagnosis rates in remote Indigenous communities have been up to 30 times higher than for non-Indigenous Australians. The high levels of population movement known to occur between remote communities may contribute to these high rates. METHODS: We developed an individual-based computer simulation model to study the relationship between population movement and the persistence of gonorrhoea and chlamydia transmission within hypothetical remote communities. RESULTS: Results from our model suggest that short-term population movement can facilitate gonorrhoea and chlamydia persistence in small populations. By fixing the number of short-term travellers in accordance with census data, we found that these STIs can persist if at least 20% of individuals in the population seek additional partners while away from home and if the time away from home is less than 21 days. Periodic variations in travel patterns can contribute to increased sustainable levels of infection. Expanding existing STI testing and treatment programs to cater for short-term travellers is shown to be ineffective due to their short duration of stay. Testing and treatment strategies tailored to movement patterns, such as encouraging travellers to seek testing and treatment upon return from travel, will likely be more effective. CONCLUSION: High population mobility is likely to contribute to the high levels of STIs observed in remote Indigenous communities of Australia. More detailed data on mobility patterns and sexual behaviour of travellers will be invaluable for designing and assessing STI control programs in highly mobile communities.

Frequent occurrence of undiagnosed pelvic inflammatory disease in remote communities of central Australia.

OBJECTIVE: To assess the extent of diagnosed and undiagnosed pelvic inflammatory disease (PID) in Aboriginal women in remote central Australia. DESIGN, SETTING AND SUBJECTS: Retrospective cross-sectional study in five remote central Australian primary health care centres. Medical records of all resident Aboriginal women aged 14-34 years were examined. Data were from presentations with documented lower abdominal pain, excluding other causes, for 2007-2008. MAIN OUTCOME MEASURES: PID investigations undertaken, PID diagnoses made, recommended treatment, and presentations meeting the guideline criteria for diagnosing PID based on pelvic examination, symptom profile or history. RESULTS: Of 655 medical records reviewed, 119 women (18%) presented 224 times with lower abdominal pain. Recommended investigations to diagnose PID were infrequently undertaken: bimanual examination (15 cases [7%]); testing for gonorrhoea and chlamydia (78 [35%]); and history taking for vaginal discharge (59 [26%]), intermenstrual bleeding (27 [12%]) and dyspareunia (17 [8%]). There were 95 presentations (42%) consistent with guidelines to diagnose PID, most (87 [39%]) based on symptom profile and history. Of these, practitioners made 15 diagnoses of PID, and none had the recommended treatment documented. CONCLUSION: Pelvic inflammatory disease occurred frequently among Aboriginal women in central Australia during the study period but was vastly underdiagnosed and poorly treated. Undiagnosed or inadequately treated PID leads to poorer reproductive health outcomes in the long term. Increased awareness of PID symptoms, diagnosis and treatment and a revision of the guidelines is needed to improve detection and management of PID in this high-risk setting.

Epidemiology of chlamydia and gonorrhoea among Indigenous and non-Indigenous Australians, 2000-2009.

OBJECTIVES: To assess notification trends for chlamydia and gonorrhoea infections in Indigenous Australians compared with non-Indigenous Australians in 2000-2009. DESIGN AND SETTING: We assessed trends in national notification rates using univariate Poisson regression and summary rate ratios. MAIN OUTCOME MEASURES: Crude notification rates and summary rate ratios, by Indigenous status, sex, age and area of residence. RESULTS: Over the 10-2012 period studied, chlamydia notification rates per 100,000 increased by 80% from 1383 in 2000 to 2494 in 2009 among Indigenous people, and by 335% from 51 in 2000 to 222 in 2009 among non-Indigenous people. The Indigenous versus non-Indigenous summary rate ratio was 23.92 (95% CI, 23.65-24.19; P<0.001). Gonorrhoea notification rates per 100,000 increased by 22% from 1347 in 2000 to 1643 in 2009 among Indigenous people, and by 70% from 10 in 2000 to 17 in 2009 among non-Indigenous people. The gonorrhoea summary notification rate ratio in Indigenous compared with non-Indigenous people was 173.78 (95% CI, 170.81-176.80; P<0.001). In Indigenous people, the highest chlamydia and gonorrhoea notification rates were in women, 15-19-2012-olds, and those living in remote areas. CONCLUSIONS: Chlamydia and gonorrhoea notification rates have increased in both populations but were higher among Indigenous people. Our findings highlight the need for targeted prevention programs for young people, especially Indigenous Australians residing in remote areas.

Australian trachoma surveillance annual report, 2010.

Endemic trachoma continues to exist in remote Aboriginal communities in Australia. The National Trachoma Surveillance and Reporting Unit, established in 2006, is responsible for the collation, analysis and reporting of trachoma prevalence data and the documentation of trachoma control strategies in Australia. Data were collected from Aboriginal communities designated at-risk for endemic trachoma (defined as prevalence of 5% or greater among children) within the Northern Territory, South Australia and Western Australia. This report presents data collected in 2010. Aboriginal children aged 1-14 years were screened using the World Health Organization grading criteria to diagnose and classify individual cases of trachoma. Aboriginal adults aged 40 years or older were screened for trichiasis. Community screening coverage of the designated at-risk communities was 60% in 2010. Screening coverage of the estimated population of children aged 1-14 years and of adults aged 40 years or older in at-risk communities was 11.5% and 5%, respectively. Trachoma prevalence among children aged 1-14 years who were screened was 11%. Of the communities screened, 36% were found to have no cases of active trachoma and 55% were found to have endemic levels of trachoma. Treatment coverage of active cases and their contacts varied between jurisdictions from 64% to 90%. Trichiasis prevalence was 4% within the screened communities.

Impact of Testing Strategies to Combat a Major Syphilis Outbreak Among Australian Aboriginal and Torres Strait Islander Peoples: A Mathematical Modeling Study.

Background: A syphilis outbreak among Australian Aboriginal and Torres Strait Islander people (respectfully referred to as Aboriginal) has resulted in almost 4000 notifications by 2020, with several congenital syphilis cases and infant deaths. Outbreak control efforts became coordinated under a National enhanced test and treat response in 2017. We evaluated the impact of these efforts and of expansion of testing interventions on syphilis prevalence. Methods: We developed an individual-based mathematical model of infectious syphilis transmission among young heterosexual Aboriginal people aged 15-34 years living in and moving between regional and remote areas, and we assessed the impact of existing and hypothetical outbreak control responses on syphilis prevalence. Results: The increased testing coverage achieved through the response (from 18% to 39% over 2011-2020) could stabilize the epidemic from 2021. To return to pre-outbreak prevalence (<0.24%) by 2025, testing coverage must reach 60%. The addition of annual community-wide screening, where 30% of youth in communities are tested over 6 weeks, would reduce prevalence to the pre-outbreak level within 4 years. If testing coverage had been scaled-up to 60% at the start of outbreak in mid-2011, the outbreak would have been mitigated. Conclusions: Our results suggest that to control the syphilis outbreak, the response needs to be delivered to enable the maximum coverage of testing to be reached in the shortest time to reduce the prevalence to pre-outbreak levels. Reduction could be hastened with community-wide screening at similar time periods across all communities together with increases in annual testing coverage.