The seroprevalence of antibodies to Japanese encephalitis virus in five New South Wales towns at high risk of infection, 2022: a cross-sectional serosurvey.

OBJECTIVES: To determine the proportion of people in New South Wales towns at high risk of Japanese encephalitis virus (JEV) infections during the 2022 outbreak; to identify risk factors for JEV infection. STUDY DESIGN: Cross-sectional serosurvey study of the seroprevalence of JEV-specific antibodies in NSW. SETTING, PARTICIPANTS: Convenience sample of people (all ages) from five regional NSW towns deemed to be at high risk of JEV infections after first outbreak of Japanese encephalitis in southeastern Australia in early 2022 (Balranald, Corowa, Dubbo, Griffith, Temora), 21 June - 22 July 2022. MAIN OUTCOME MEASURES: Proportion of people seropositive for JEV total antibody, assayed by defined epitope-blocking enzyme-linked immunosorbent assay; prevalence odds ratios for exposure risk factors and protective behaviours. RESULTS: Eighty of 917 eligible participants (559 girls or women, 61%; 42 Aboriginal and Torres Strait Islander people, 4.6%; median age, 52 years [IQR, 37-62 years]) were seropositive for JEV-specific total antibody (8.7%); the median age of seropositive people was 61 years (IQR, 48-70 years). The seropositivity proportion was largest for people aged 65 years or more (30 of 192; weighted proportion, 13.7%) and larger for male than female participants (30 of 358, 10.6% v 50 of 559, 7.5%). Five of 42 samples from Aboriginal and Torres Strait Islander participants were seropositive (12%). We found mixed associations with a range of potential risk factors. CONCLUSION: We found evidence for a substantial number of JEV infections in five regional NSW towns during a single arbovirus season in 2022. Public health responses, including effective surveillance, vaccination against JEV, and mosquito management, are critical for controlling outbreaks. Promoting behaviours that reduce exposure to mosquitoes is a core component of prevention, particularly when the vaccine supply is limited.

The New South Wales Mouse Plague 2020-2021: A One Health description.

A mouse plague occurred in Eastern Australia from spring 2020 to winter 2021, impacting an area of around 180,000 km2. It harmed human physical and psychological health, damaged the natural and built environment, and endangered farmed, domestic and native animals. However, the mouse plague was overshadowed by the COVID-19 pandemic, especially as the end of the plague coincided with the arrival and surge of the COVID-19 delta strain in rural New South Wales (NSW). In this article, we systematically overview the multiple impacts of the plague and highlight their complex interactions. Using a One Health framework, we comprehensively review the i) human, ii) animal and iii) environmental impacts including economic dimensions. Given the damage that the mouse plague caused to infrastructure, we consider the environment from two perspectives: the natural and the built environment. This One Health description of the 2020-2021 mouse plague identifies priorities for preparedness, response and recovery at local, regional land levels to inform response and management of future mouse plague events in Australia. It also highlights the need for ongoing collaboration between researchers and practitioners in the human, animal and environmental health sectors.

Influenza outbreaks in aged care facilities in New South Wales in 2017: impact and lessons for surveillance.

INTRODUCTION: A record number of influenza outbreaks in aged care facilities (ACFs) in New South Wales (NSW) during 2017 provided an opportunity to measure the health impact of those outbreaks and assess the quality of routinely available surveillance data. METHODS: Data for all ACF influenza outbreaks in NSW in 2017 were extracted from the Notifiable Conditions Information Management System. The numbers of outbreaks, residents with influenza-like illness (ILI), hospital admissions and deaths were assessed. For each outbreak the attack rate; duration; timeliness of notification; resident and staff influenza vaccination coverage; and antiviral use for treatment or prophylaxis were analysed. Data were considered for NSW in total and separately for seven of the state's local health districts. Data completeness was assessed for all available variables. RESULTS: A total of 538 ACF outbreaks resulted in 7,613 residents with ILI, 793 hospitalisations and 338 deaths. NSW outbreaks had a median attack rate of 17% and median duration of eight days. Data completeness, which varied considerably between districts, limited the capacity to accurately consider some important epidemiological and policy issues. DISCUSSION: Influenza outbreaks impose a major burden on the residents and staff of ACFs. Accurate assessment of the year-to-year incidence and severity of influenza outbreaks in these facilities is important for monitoring the effectiveness of outbreak prevention and management strategies. Some key data were incomplete and strategies to improve the quality of these data are needed, particularly for: the number of influenza-related deaths among residents; resident and staff vaccination coverage prior to outbreaks; and recorded use of antiviral prophylaxis.

Atypical outbreak of Q fever affecting low-risk residents of a remote rural town in New South Wales.

We investigated an outbreak of Q fever in a remote rural town in New South Wales, Australia. Cases identified through active and passive case finding activities, and retrospective laboratory record review were interviewed using a standard questionnaire. Two sets of case-case analyses were completed to generate hypotheses regarding clinical, epidemiological and exposure risk factors associated with infection during the outbreak. Laboratory-confirmed outbreak cases (n=14) were compared with an excluded case group (n=16) and a group of historic Q fever cases from the region (n=106). In comparison with the historic case group, outbreak cases were significantly more likely to be female (43% vs. 18% males, P = 0.04) and identify as Aboriginal (29% vs. 7% non-Aboriginal, P = 0.03). Similarly, very few cases worked in high-risk occupations (21% vs. 84%, P < 0.01). Most outbreak cases (64%) reported no high-risk exposure activities in the month prior to onset. In comparison with the excluded case group, a significantly increased proportion of outbreak cases had contact with dogs (100% vs. 63%, P = 0.02) or sighted kangaroos on their residential property (100% vs. 60%, P = 0.02). High rates of tick exposure (92%) were also reported, although this was not significantly different from the excluded case group. While a source of this outbreak could not be confirmed, our findings suggest infections likely occurred via inhalation of aerosols or dust contaminated by Coxiella burnetii, dispersed through the town from either an unidentified animal facility or from excreta of native wildlife or feral animals. Alternatively transmission may have occurred via companion animals or tick vectors.

Farmers' knowledge of Q fever and prevention approaches in New South Wales.

OBJECTIVE: To identify what New South Wales (NSW) farmers know about Q fever to inform preventive approaches. DESIGN: Thematic analysis of qualitative data gathered through semi-structured individual interviews, focus groups and a community meeting. SETTING: Rural communities in NSW, Australia. PARTICIPANTS: A total of 25 farmers participated in individual interviews (n = 4) or three focus groups, each with seven participants (n = 21). A further 27 persons, were involved in a community meeting. MAIN OUTCOME MEASURES: Themes derived from the interviews, focus groups and community meeting. RESULTS: Knowledge variations regarding Q fever risk and transmission highlight a need for improved risk communication. Vaccination was viewed as the preferred prevention approach; barriers were raised including time, costs, access to screening/vaccination and General Practitioner (GP) knowledge about Q fever. Local vaccination initiatives were supported. CONCLUSIONS: Strengthening existing GP knowledge and services leading to expanded provision of screening/vaccination could improve the coverage of Q fever vaccine in endemic NSW farming and rural communities.