Background and Aim
Australian bat lyssavirus (ABLV) is a rare but fatal zoonotic infection in humans which is transmitted through bites or scratches from infected bats. Although the prevalence of ABLV in bat populations is low, the severity of human disease necessitates a prompt public health response after each potential exposure. In Queensland, Australia, potential ABLV exposure is a notifiable condition which requires Public Health Units (PHUs) to undertake risk assessment and coordinate post-exposure prophylaxis (PEP).
In 2025, Queensland experienced a marked increase in notifications of potential ABLV exposure. The Darling Downs Public Health Unit (DDPHU), serving the rural and regional areas in southwest and part of southeast Queensland, recorded its highest annual number in more than a decade. This has substantially increased the PHU’s workload and highlights the need to better understand both epidemiological trends, increasing risk behaviours and operational challenges associated with managing potential ABLV exposures.

Methods and Analysis
This study is a retrospective mixed-methods review of potential ABLV exposure notifications managed by DDPHU between 2011 and 2025. Quantitative analysis is conducted using routinely collected surveillance and case management data extracted from the Notifiable Conditions System (NoCS) and DDPHU records. This analysis will include descriptive epidemiology to identify temporal and spatial trends of demographic characteristics, exposure circumstances and PEP provision. Qualitative analysis of meeting records is undertaken using a framework analysis approach to identify operational and practical challenges encountered by DDPHU staff in managing potential ABLV exposure notifications.

Outcomes
This study is expected to identify shifts in epidemiology and circumstances of potential ABLV exposures over time and as well as key operational challenges related to workload and service delivery.

Conclusion and Future actions
Findings can inform service planning, optimise PHU management of potential ABLV exposure notifications, and support targeted public health messaging to reduce future exposure risk.

Background and Aim

Australian bat lyssavirus (ABLV) is a rabies-related lyssavirus endemic in Australian flying foxes and microbats. As of 2026, there have been only 4 reported cases, all fatal. In Australia, public health units support post-exposure prophylaxis (PEP) following bat exposures and provide guidance to clinicians on risk assessment, PEP product access and administration.

In 2025, NSW recorded its first ABLV case. This is also the first case in Australia to have developed the disease after receiving PEP.

Methods and Analysis

The public health investigation covered risk assessment of the exposure period and disease onset. A multidisciplinary expert panel was formed with expertise in infectious diseases, immunology, vaccinology, microbiology and public health to support advice and decision-making.

Provision of PEP was reviewed, including timing, dosing, technique, cold chain and wound care, in-line with Australian Immunisation Handbook guidance. Contact tracing covered healthcare and community settings, focusing on potential mucosal or percutaneous exposure to infectious body fluids.

Outcomes

The expert panel concluded that PEP had been administered appropriately and in accordance with national guidelines, including timely initiation, correct dosing, administration technique and product handling. Cold-chain investigations and referrals for batch testing did not identify any product issues.

Of 58 contacts identified through contact tracing, PEP was recommended for 5% (n=3).

Conclusions and future actions

This case highlights the critical role of PHUs and Health Protection NSW in leading coordinated responses to rare and complex infectious disease events. Rapid mobilisation of a trusted expert network enabled timely assurance, consistent messaging and system-wide learning.

The expert panel findings were referred to the Australian Technical Advisory Group on Immunisation (ATAGI), with outcomes pending. Additional work is underway to comprehensively detail the presentation and pathology. Strengthening national and jurisdictional mechanisms for expert collaboration will be essential to support future responses to rare zoonotic infections.

Background and aim

Dengue is a notifiable, mosquito-borne viral infection of significant clinical and public health importance. The most common vector, Aedes genus mosquitos, are only found in tropical or sub-tropical regions of Australia. Non-vector-based transmission routes are rarely reported. Dengue belongs to the Flaviviridae family, which includes Zika virus – a virus with sexual transmission pathway. We describe a case of potentially sexually transmitted dengue in Victoria, Australia, and the subsequent public health investigation.

Methods and Analysis

A dengue case was notified in a female in her 20’s in Melbourne, Victoria She reported no interstate or overseas travel; her male partner, a confirmed dengue case had recently returned from Indonesia, a known endemic area. An outbreak investigation was undertaken, which included case, contact and environmental investigations and management. Potential vector-borne and non-vector routes were investigated. A semen sample was collected 53 days after the symptom onset in the male partner and tested for dengue. Whole genome sequencing (WGS) of viral samples from both the case and their partner was also completed.

Outcomes

The case denied other plausible routes of acquiring infection and confirmed unprotected sexual contact with her partner. Case investigations confirmed both the case and partner had dengue virus serogroup 2 via PCR, with WGS demonstrating near identical genomes. Dengue was not detected in the semen sample. Mosquito surveillance was undertaken on properties that both cases had attended to investigate potential local vector-borne transmission. No competent vectors were identified.

Conclusion and Future actions

The results of this outbreak investigation, the similarity between the Dengue and Zika viruses as well as WGS, support the plausible sexual transmission of dengue virus between the case and her male partner. Public health investigations in non-endemic areas should consider this a plausible pathway of infection. Further research is required to conclusively demonstrate sexual contact as a transmission route.

Background and aim
In Australia, extensively-drug resistant (XDR) Shigella sonnei biotype g infections have predominantly been associated with men who have sex with men (MSM). In December 2025, the WA Department of Health (DoH) investigated an outbreak of S. sonnei biotype g to identify transmission pathways and implement public health control measures.
Methods and analysis
S. sonnei biotype g cases were notified under the Public Health Act, 2016. Isolates underwent anti-microbial susceptibility testing and whole genome sequencing. Cases and symptomatic contacts with illness onset in November-December 2025 and residing in the affected town were interviewed using a hypothesis generating questionnaire. Data were analysed descriptively.
Outcomes
Ten cases (five confirmed, five probable) were identified. The median age was eight years (range 4-41 years), with illness onset ranging from 24/11/25-27/12/25. The median diarrhoea duration was eight days. The likely primarycase was a probable case identifying as MSM who developed diarrhoea on 24/11/25 after returning from interstate and stayed with his sister’s family, all of whom later became ill, including a six-year-old child. Two children from two other families, who were friends or school contacts of the six-year-old, also became ill. The mother of one of these children later became ill. All Shigella isolates were XDR, had the ESBL blaCTX-M-15 gene and were genomically clustered (<5 SNPs).
Conclusion
This investigation is the first reported community outbreak of XDR shigellosis in WA, mostly affecting young children. This genomic strain emerged in WA in 2024, primarily in Perth and is common in eastern Australia, where it is often linked to MSM transmission. This outbreak demonstrates how XDR shigellosis can be introduced into new populations and spread quickly, particularly among young children with lower levels of hand hygiene. Public health agencies have an important role in providing timely advice to prevent onwards transmission.

Background and Aim: Invasive meningococcal disease (IMD) is a vaccine-preventable disease caused by the Neisseria meningitidis bacteria. On 28th August 2025, the Western Public Health Unit (WPHU) were notified of a case of IMD in a 28-year-old male identified as a household-like contact of a previous case notified on 8th June 2025. WPHU investigated the cluster and conducted contact management.

Methods and Analysis: Investigation included case interviews, contact identification to inform antibiotic and vaccine provision, and laboratory investigations.

Outcomes: Two cases were identified in this cluster. From the first case, of eight identified household-like contacts, seven (including the person who later developed disease) had received clearance antibiotics (CAB) and one developed symptoms and was given antibiotics as treatment but tested negative. The case was caused by N. meningitidis serogroup B, so vaccine was not initially offered to contacts per the Australian guidelines. From the second case, 11 household-like contacts were identified of which all were given CAB.

Although there was an epidemiological link between the first and second case, genomic linkage could not be ascertained as bacterial growth was not possible in the second case. N. meningitidis serogroup B was detected in both.

In view of the unusual situation of multiple IMD cases of the same serogroup within a short period of time and many people living in close quarters, vaccine PEP (MenB) was offered to all contacts: five considered vaccination, of which one successfully completed their course. No subsequent cases occurred.

Conclusions and Future Actions: Possible causes of this cluster of IMD include coincidence, CAB failure, and unrecognised close contacts. This unusual incident demonstrates the importance of contact management, communication, and consideration of providing PEP to eligible contacts outside of the usual scope of public health management in order to prevent additional cases in a household setting.

Background: Invasive group A Streptococcus (iGAS), caused by Streptococcus pyogenes, can progress rapidly and lead to severe complications. Transmission of group A Streptococcus (GAS) can occur in healthcare during close patient contact. We describe a healthcare-associated exposure in which staff cared for a patient with undiagnosed iGAS in a Sydney emergency department, after which several healthcare workers developed symptomatic GAS infection.

Methods: An outbreak investigation followed identification of iGAS bacteraemia in a patient presenting to an emergency department. Eighteen health care workers (HCWs) were exposed during the patient’s admission, including a cardiac arrest event; 16 were interviewed. Exposure history, symptom onset, clinical course, microbiological testing, and infection prevention practices were assessed through contact tracing and clinical review. Whole-genome testing was performed on the patient’s isolate.

Results: Six of eighteen exposed HCWs developed tonsilitis or influenza like illness, yielding a symptomatic attack rate of 33% (6/18). Four HCWs had laboratory confirmed GAS infection with a confirmed attack rate of 22% (4/18, 95%CI: 7-49%). One HCW was clinically diagnosed as GAS infection despite a negative culture, and one HCW had compatible symptoms but was not tested. All symptomatic HCWs had contact with the patient prior to cardiac arrest, whereas none without pre-arrest contact became unwell. The estimated mean incubation period was 2.7 days and Illness duration ranged from one day to two weeks. PPE use during care was inconsistently recalled, however no HCWs reported use of N95/P2 respirators. Whole genome sequencing of the patient’s isolate identified emm type 3.93, reported as an emerging type in Europe.

Conclusions: GAS transmission occurred predominantly among HCWs with prolonged close contact during routine bedside care prior to cardiac arrest.

Implications for Public Health: Duration and proximity of routine patient contact may contribute substantially to occupational GAS transmission, and current exposure definitions do not capture this risk.

Background and Aim
Streptococcus pyogenes (Strep A) is a human-specific bacterial pathogen which causes superficial and invasive infections and serious post-infectious disease. Inequitable housing and living conditions are strongly associated with Strep A infections and related diseases. The burden is disproportionately high for Aboriginal and Torres Strait Islander people who remain impacted by settler colonialism in Australia. Improving environmental health is a priority. However, environmental survival of Strep A and specific modes of transmission are not fully understood, which leads to confusion and inconsistent clinical and public health advice. This includes common recommendations for washing clothes and bedding. The aim of this work is to improve understanding of the role of fabrics in Strep A transmission and the value of washing to help manage infection.

Methods and Analysis
Our multidisciplinary research program involved literature reviews, laboratory experiments, and place-based work. We present new knowledge on Strep A viability on fabrics and explore methods for effective laundering.

Indigenous Governance Structures
Our team comprises Indigenous and non-Indigenous collaborators. The agenda for this project was set by the Indigenous Governance Council (IGC) of an NHMRC-funded work focused on Indigenous environmental health to prevent Strep A infection (STARFISH). Ongoing review and input from the IGC continues to guide the direction of this project. We are committed to place-based work that builds capacity and privileges Aboriginal ways of knowing, being and doing (WAAHEC HREC: 1412).

Outcomes and Conclusion
The viability of Strep A on fabrics declines rapidly at first, but low-level survival can occur for extended durations (from hours to months) depending on environmental conditions. Fabric fomite transmission is therefore possible, but unlikely to be a major reservoir of Strep A or driver of infection. Reducing fabric contamination with other relevant skin pathogens and ectoparasites may indirectly reduce Strep A skin infections. Washing or drying fabrics at high temperatures (60C), or lower temperature washing with detergent containing activated oxygen bleach (AOB) are reliable approaches to decontamination. Access to facilities for washing clothes and bedding (Healthy Living Practice 2/HLP2) for Aboriginal and Torres Strait Islander families is a human right, contributing to wellbeing and potentially supporting skin health. HLP2 is likely to play a role in helping to manage severe cases of active skin infections/infestations.

Background and Aim

Reinfections with legionellosis are uncommon but have been recognised in clinical and public health practice. The absence of a defined reinfection or repeat notification period presents challenges for surveillance and case management, particularly when distinguishing true reinfection from relapse of a previous infection and assessing the public health risk associated with exposure sites visited by cases. Clinical, microbiological, and epidemiological information should be considered when assessing whether a second legionellosis notification represents true reinfection or relapse. We describe two likely reinfection cases identified in residents of the North-Eastern Public Health Unit (NEPHU) catchment within a 12-month period and outline system-level actions taken to strengthen statewide guidance.

Methods and Analysis

NEPHU Public Health Officers identified potential reinfection cases during follow-up of legionellosis notifications. Detailed review of notification data, laboratory results, and clinical histories was undertaken. The likelihood of reinfection was evaluated using the time between initial and second symptom onset, evidence of clinical recovery between notifications, treating clinicians’ opinions, and rapid review of published literature.

Outcomes

Two cases, a 78-year-old male with Legionella pneumophila serogroup 1 and a 53-year-old male with Legionella longbeachae, experienced second symptomatic episodes more than 12 months after recovery from their initial legionellosis infection. The prolonged interval between episodes, clear recovery periods, and treating clinicians’ assessments supported the classification of both cases as likely reinfections rather than relapses. Following discussion with the Victorian Department of Health, guidance regarding reinfection assessment has been incorporated into the updated statewide protocol for legionellosis management.

Conclusion and Future Actions

Routine collection of sputum for PCR and culture should be prioritised for all legionellosis notifications to improve diagnostic certainty and enable genomic comparison between episodes. Systematic review and assessment of potential reinfection cases across jurisdictions could support the development of a formal reinfection timeframe and strengthen guidance on the management of reinfection cases.

Background and aim: Eliminating Hepatitis C virus (HCV) by 2030 is a national priority, yet regional and marginalised populations face significant barriers to testing and treatment. This study will evaluate the feasibility, acceptability, and effectiveness of a decentralised, nurse-led, point-of-care HCV testing, enhanced follow-up, and treatment model delivered within harm reduction services in the regional Ovens Murray area of North-East Victoria.

Methods and analysis: This is a prospective observational study recruiting existing clients of Gateway Health’s (the largest community health centre in Ovens Murray) harm reduction services. Participants undergo finger-prick point-of-care HCV RNA testing (GeneXpert HCV Viral Load Fingerstick Assay) and laboratory testing for HCV, Hepatitis B Virus, and HIV. HCV-positive participants are offered treatment prescribed by authorised Nurse Practitioners, with follow-up support tailored to individual needs (classified as minimal, moderate, or high intensity). Structured interviews are administered at enrolment and post-intervention to collect data on demographics, risk behaviours, mental health symptoms, service barriers/enablers and acceptability of the intervention. Data will be analysed using descriptive statistics and logistic regression to examine factors associated with retention in care and blood-borne virus status.

Outcomes: There are few studies from rural Australia that evaluate the feasibility, effectiveness and acceptability of decentralised nurse-led models of hepatitis C testing and treatment in community settings. Preliminary data from this model will be presented. Findings will be used to inform expansion of the model to other high-risk groups and settings and to improve service delivery for people at high risk of HCV in regional Australia.

Conclusion and future actions: Locally designed, nurse-led models of care may improve HCV testing, treatment, and follow-up among high-risk populations. Results will guide future service design, support broader implementation, and contribute to achieving national HCV elimination targets by 2030.

Background and Aim
A hepatitis A exposure at a hostel in June 2025 generated 652 contacts over 23 days. Per the Victorian protocol¹ for exposure management, Western Public Health Unit (WPHU) recommended one dose of hepatitis A vaccine as post-exposure prophylaxis (PEP) for eligible contacts (n=323), defining eligibility as hostel residents who could receive PEP within 14 days from their last exposure to the infectious case. At short notice, the local council arranged a vaccination clinic for hostel guests and staff within 14 days since last possible exposure, which delivered PEP to 21 hostel contacts (3.2%).
There is variability among international jurisdictions and sub-nationally in determining hepatitis A PEP eligibility. Australia has a susceptible population to hepatitis A², and whilst this exposure resolved without any known secondary cases, adherence to other protocols could have increased PEP uptake. We project this situation on different protocols to highlight disparities and inform optimal response.

Methods and Analysis
We compared eligibility definitions across the Victorian, Australian (SoNG)³, and United Kingdom⁴ protocols, assuming the same proportion of eligible contacts would receive PEP in each scenario to project the number of contacts protected against hepatitis A through a vaccination clinic.

Outcomes
The real-world (Victorian) outcome vaccinated 21 contacts. Adherence to the SoNG would have vaccinated 0 contacts, as the clinic would not have been set-up within 14 days of the case’s symptom onset. 42 contacts would have been vaccinated by following the United Kingdom’s protocol, double that achieved in Victoria.

Conclusion and Future Actions
Estimated protection against hepatitis A infection from PEP within 14 days of exposure is high (96-99%)⁵, yet unknown beyond this cut-off day⁶. Vaccination 14 days post-exposure likely prevents the occurrence of tertiary cases in household-like settings⁷. We recommend consideration of flexibility in the 14-day cut-off where longer periods could increase PEP uptake.

References
1. Department of Health Victoria (2025). Hepatitis A Protocol, page 16. (Not publicly accessible).
2. Communicable Diseases Network Australia (Series of National Guidelines) (2025). Hepatitis A National Guidelines for Public Health Units, page 8. https://www.cdc.gov.au/system/files/2025-09/hepatitis-a-cdna-national-guidelines-for-public-health-units.pdf
3. Communicable Diseases Network Australia (Series of National Guidelines) (2025). Hepatitis A National Guidelines for Public Health Units, page 12. https://www.cdc.gov.au/system/files/2025-09/hepatitis-a-cdna-national-guidelines-for-public-health-units.pdf
4. UK Health Security Agency (2024). Public health control and management of hepatitis A 2024: updated guidance, page 27. https://assets.publishing.service.gov.uk/media/65ccdbbd1d93950012946677/Hepatitis-A-guidance-13-february-2024.pdf
5. Parrón, I., Planas, C., Godoy, P., Manzanares-Laya, S., Martínez, A., … Sala, M. R. (2017). Effectiveness of hepatitis A vaccination as post-exposure prophylaxis. Human Vaccines & Immunotherapeutics, 13(2), 423–427. https://doi.org/10.1080/21645515.2017.1264798
6. Nelson NP, Link-Gelles R, Hofmeister MG, et al. Update: Recommendations of the Advisory Committee on Immunization Practices for Use of Hepatitis A Vaccine for Postexposure Prophylaxis and for Preexposure Prophylaxis for International Travel. MMWR Morb Mortal Wkly Rep 2018;67:1216–1220. DOI: http://dx.doi.org/10.15585/mmwr.mm6743a5.
7. UK Health Security Agency (2024). Public health control and management of hepatitis A 2024: updated guidance, page 25. https://assets.publishing.service.gov.uk/media/65ccdbbd1d93950012946677/Hepatitis-A-guidance-13-february-2024.pdf

Background:
Between 2015–2024, South Western Sydney Local Health District recorded a five-fold increase in infectious syphilis notifications. During this period, male-to-female notification ratio shifted from 14:1 (2015) to 4:1 (2024), indicating a growing burden of disease among females. Over an 18-month period in 2024–2025, SWSLHD reported five congenital syphilis cases. This highlights a significant public health challenge in a region with highly diverse community characterised by socio-economic disadvantage, lower health-literacy, and migration-related barriers contributing to missed opportunities for syphilis screening and treatment.

Aim:
To strengthen follow-up of syphilis in pregnancy and prevent congenital infections through improved surveillance, engagement, and multidisciplinary coordination.

Methods and Analysis:
A retrospective audit was conducted of confirmed infectious syphilis cases in pregnant females aged ≤46 years, notified to the SWS Public Health Unit (PHU) between August 2024 and August 2025. An audit tool assessed compliance with antenatal screening and management in accordance with the NSW Syphilis in Pregnancy and Newborns Policy Directive and ASID Management of Perinatal Infections. Analysis identified gaps in antenatal screening, treatment adherence, care coordination, and communication pathways.

Outcomes:
Audit findings informed the development of a quality improvement model focused on enhanced case management, cross service linkage, and systematic monitoring of all pregnant syphilis cases. A “syphilis in pregnancy and newborn” dashboard was introduced to support timely testing, treatment compliance, and multidisciplinary case review. Engagement through the SWSLHD Syphilis Control Steering Committee strengthened collaboration across perinatal, pediatric, sexual health, midwifery, drug and alcohol, and health promotion services.

Conclusion and Future Actions:
Audit findings strengthened monitoring and management of syphilis in pregnancy and newborn follow-up. PHU oversight and leadership has been enhanced with the goal of eliminating congenital syphilis in SWSLHD. Future actions include quarterly audits to monitor guideline compliance and continued culturally responsive strategies to meet the needs of the diverse SWSLHD community.