Preventing early childhood transmission of hepatitis B in remote aboriginal communities in Northern Australia.

BACKGROUND: Chronic hepatitis B is a public health concern in Aboriginal communities in the Northern Territory of Australia with prevalence almost four times the non-Aboriginal population. Infection is suspected to mainly occur in early life, however, the mode of transmission and vaccine effectiveness is not known in this population. WHO has set a target for hepatitis B elimination by 2030; elimination in this disproportionately affected population in Australia will require understanding of the modes of transmission and vaccine effectiveness. METHODS: We conducted the study at four very remote Aboriginal communities. We approached mothers who had chronic hepatitis B and had given birth between 1988 and 2013 for consent. We obtained hepatitis B serology, immunisation and birth details from the medical record. If both mother and child had hepatitis B viral DNA detected, we performed viral whole genome sequencing. RESULTS: We approached 45 women for consent, of whom 23 agreed to participate. We included 20 mothers and 38 of their children. Of the 20 included mothers, 5 (25%) had children who were hepatitis B immune by exposure and 3 (15%) had children with evidence of chronic hepatitis B infection at the time of assessment. Hepatitis B immunoglobulin (HBIg) had been given at birth in 29/38 (76.3, 95% CI 59.8-88.6) children, and 26 children (68.4, 95% CI 51.3-82.5) were fully vaccinated. Of the 3 children who had chronic hepatitis B, all had received HBIg at birth and two were fully vaccinated. Of the 5 who were immune by exposure, 4 had received HBIg at birth and one was fully vaccinated. Whole genome sequencing revealed one episode of definite mother to child transmission. There was also one definite case of horizontal transmission. CONCLUSIONS: Chronic hepatitis B in this context is a sensitive issue, with a high proportion of women refusing consent. Although uncommon, there is ongoing transmission of hepatitis B to Aboriginal children in remote northern Australia despite vaccination, and this is likely occurring by both vertical and horizontal routes. Prevention will require ongoing investment to overcome the many barriers experienced by this population in accessing care.

Point of care and oral fluid hepatitis B testing in remote Indigenous communities of northern Australia.

Many Indigenous Australians in northern Australia living with chronic hepatitis B are unaware of their diagnosis due to low screening rates. A venous blood point of care test (POCT) or oral fluid laboratory test could improve testing uptake in this region. The purpose of this study was to assess the field performance of venous blood POCT and laboratory performance of an oral fluid hepatitis B surface antigen (HBsAg) test in Indigenous individuals living in remote northern Australian communities. The study was conducted with four very remote communities in the tropical north of Australia's Northern Territory. Community research workers collected venous blood and oral fluid samples. We performed the venous blood POCT for HBsAg in the field. We assessed the venous blood and oral fluid specimens for the presence of HBsAg using standard laboratory assays. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the POCT and oral fluid test, using serum laboratory detection of HBsAg as the gold standard. From 215 enrolled participants, 155 POCT and 197 oral fluid tests had corresponding serum HBsAg results. The POCT had a sensitivity of 91.7% and specificity of 100%. Based on a population prevalence of 6%, the PPV was 100% and NPV was 99.5%. The oral fluid test had a sensitivity of 56.8%, specificity of 98.1%, PPV of 97.3% and NPV of 65.9%. The venous blood POCT has excellent test characteristics and could be used to identify individuals with chronic HBV infection in high prevalence communities with limited access to health care. Oral fluid performance was suboptimal.