Objectives:To estimate the prevalence of chronic hepatitis B virus (HBV) infection in Australia and attributable proportions associated with specific demographic groups at higher risk of infection. Methods: Two methods were used to estimate prevalence of HBV surface antigen (HBsAg): (1) Population-based: results of a national serosurvey using sera collected opportunistically from laboratories across Australia were used for 1-59 year olds, with the HBsAg prevalence for 50-59 years extrapolated to the population aged 60 years and over; (2) Risk group-based: estimates for selected high-risk groups (injecting drug users, homosexual men, Indigenous Australians and people born in highprevalence countries), using source data from antenatal HBV screening in central Sydney, HBV prevalence studies, and estimates for low-risk groups (first-time blood donors) were combined proportionally to their representation in the population. Results: Prevalence of HBsAg in the national serosurvey increased, with age, from 0.0% for 1-4 and 5-9 year olds to 1.3-1.8% for the 40-49 year age group. Australian population HBsAg prevalence based on minimum and adjusted estimates from this serosurvey were 91,500 (0.49%) and 163,000 (0.87%) infections, respectively. The risk group method estimated an Australian HBsAg prevalence of 88,000 infections (0.47%). Approximately 50% of people with chronic HBV infection were estimated to be immigrants from either South-East Asia (33.3%) or North-East Asia (16.2%). Conclusion: The range of estimates for chronic HBV infection in Australia is broad, reflecting the uncertainty in source data. A national blood survey encompassing a large and representative population sample may help to provide more accurate estimates. A large proportion of people with chronic HBV infection are Asian born.

Objectives To estimate the prevalence of exposure to the causative agent of Q fever (Coxiella burnetii) and of current infections among blood donors in Australia. Design, setting Cross‐sectional study in metropolitan Sydney and Brisbane, and in non‐metropolitan regions with high Q fever notification rates (Hunter New England in New South Wales; Toowoomba in Queensland). Participants Blood donors attending Red Cross collection centres during October 2014 – June 2015 who provided sera and completed a questionnaire on Q fever vaccination status, diagnosis and knowledge, and exposure history. Main outcome measures Age‐ and sex‐standardised seroprevalence of phase II IgG antibodies to C. burnetii (indicating past exposure) and independent risk factors for seropositivity; presence of C. burnetii DNA (indicating current infection and risk of transmission by blood transfusion). Results 2740 donors (94.5% response rate) completed the questionnaire and supplied sera for analysis. Crude antibody seroprevalence was 3.6%. Standardised seroprevalence was higher in non‐metropolitan than metropolitan regions (NSW, 3.7% v 2.8%; Queensland, 4.9% v 1.6%; statistically significant only in Queensland). Independent predictors of antibody seropositivity were regular contact with sheep, cattle, or goats (adjusted odds ratio [aOR], 5.3; 95% CI, 2.1–14), abattoir work (aOR, 2.2; 95% CI, 1.2–3.9), and assisting at an animal birth (aOR, 2.1; 95% CI, 1.2–3.6). Having lived in a rural area but having only rare or no contact with sheep, cattle or goats was itself a significant risk factor (v never lived rurally: aOR, 2.5; 95% CI, 1.1–5.9). 40% of people in groups recommended for vaccination were aware of the vaccine; 10% of people in these groups had been vaccinated. C. burnetii DNA was not detected in 1681 non‐metropolitan samples, suggesting that transmission by blood donation is unlikely. Conclusions Given their exposure to multiple risk factors, vaccination against Q fever should be considered for all rural residents.

Objective: To determine uptake of treatment for hepatitis C virus (HCV) infection and predictors of deferral of treatment for HCV by using prospectively collected data from the Australian Chronic Hepatitis C Observational Study (ACHOS). Design, patients and setting: Cohort study involving interview and medical record review at enrolment and routine follow‐up clinic visits of patients with chronic HCV and compensated liver disease attending a national network of 24 HCV clinics between April 2008 and December 2009. Eligible patients were those who had not been previously treated, were enrolled within 6 months of their first clinic visit, were eligible for treatment and had been enrolled for at least 6 months. Main outcome measure: Predictors of patients undergoing HCV treatment within the first 6 months of assessment. Results: 1239 patients were enrolled in ACHOS, of whom 406 met the criteria for inclusion in the subcohort for this study. Among this subcohort, 171 (42%) received treatment within 6 months of their first clinic visit. Current injecting drug use (odds ratio [OR], 0.26; 95% CI, 0.08–0.77), past and current treatment for drug dependency (OR, 0.34; 95% CI, 0.18–0.67, and OR, 0.42; 95% CI, 0.22–0.81, respectively) and alcohol use above 20 g/day (OR, 0.20; 95% CI, 0.08–0.46) were independent predictors of deferral of treatment. At least one of these factors applied to 41% of the subcohort. Clinical factors, including HCV genotype, HCV RNA level, and stage of liver disease were not associated with deferral of treatment for HCV. Conclusion: Factors related to drug and alcohol use, rather than clinical factors, influenced uptake of treatment for HCV. Further support for patients with drug and alcohol dependency is required to optimise treatment uptake.