Hepatitis--associated antigen in aboriginal groups in Northern Australia

Hepatitis B virus and human T-cell lymphotropic virus type 1 co-infection in the Northern Territory, Australia

OBJECTIVE

To establish the relationship between hepatitis B virus (HBV) and human T-cell lymphotropic virus type 1 (HTLV-1) serological markers in the Northern Territory, Australia.

METHODS

A retrospective serological study of patients presenting to public healthcare facilities in the Northern Territory between 2008 and 2015 was performed in order to determine the presence and relationships of serological markers of HBV and HTLV-1.

RESULTS

Seven hundred and forty individual patients were found to be serologically positive for HTLV-1 in the Northern Territory over the 8-year period. Hepatitis B results were available for 521 of these patients. Hepatitis B surface antigen (HBsAg) positivity was demonstrated in 15.9% (83/521) of this cohort, which was significantly different to the HTLV-1-negative group (3.7%, 125/3354) (p<0.001). Excluding individuals with isolated hepatitis B surface antibody (anti-HBs), those in the HTLV-1-positive group had a higher HBV exposure history (67.5%, 352/521) when compared to HTLV-1-negative individuals (37.8%, 1259/3354) (p<0.001). HTLV-1-positive individuals had a lower prevalence of HBV combined anti-HBs and hepatitis B core antibody (anti-HBc) positive markers compared to those who were HTLV-1-negative (56.3% (198/352) versus 73.8% (937/1269), respectively; p<0.001).

CONCLUSIONS

A significantly higher prevalence rate of HBV was found in HTLV-1-positive individuals from the Northern Territory. When considering the higher exposure to HBV in HTLV-1-positive individuals, the clearance of HBV appears lower than in those individuals testing HTLV-1-negative. A lower prevalence of clearance in HTVL-1-positive individuals than in HTLV-1-negative individuals, as signified by formation of HBVcAb and HBVsAb in HTVL-1 positive individual's may equate to higher prevalence of ongoing coinfection.

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.

Changing prevalence of hepatitis B virus in urbanized Australian aborigines

Serological surveys of desert or rural Australian Aboriginal settlements report up to 85% positivity for hepatitis B virus (HBV) markers. We report the results of two cross-sectional HBV surveys carried out 5 years apart in the bi-racial town of Condobolin, New South Wales (population 3086; 14% Aborigines). In 1983-84, none of the 310 non-Aborigines tested were hepatitis B surface antigen (HBsAg) positive but 7.2% were positive for hepatitis B core antibody (anti-HBc). Among Aboriginal subjects, 57.6% had detectable HBV markers and 16.9% were HBsAg positive. In 1987-88, no non-Aborigines were HBsAg positive and only 1% (of 422 individuals) had anti-core antibodies. In contrast, 36% of Aboriginal subjects had HBV markers and 6% were HBsAg positive. No significant difference in detectable HBV markers was found among 98 Aborigines who were included in both surveys. Migration was the main factor influencing the HBV prevalence between the two surveys. Clustering of HBsAg carriers occurred within households and the likely mode of infection was intrafamilial horizontal childhood transmission. There was a significant association between HBV markers and tattooing in Aborigines (P < 0.02). Overall, HBV markers were less frequent in this population than in other desert or rural Aboriginal populations surveyed. The prevalence of HBV infection in non-Aboriginal households was not significantly different from that in the Australian Caucasian population.

Australia's contribution to tropical health: past and present

Australian research workers have made important contributions to tropical medicine and tropical public health. Recognised high points of international significance (for example, Joseph Bancroft and filariasis, 1876; Thomas Bancroft and dengue fever, 1906; Burnet and Australian X disease, 1934; Derrick and Q fever, 1937; and Fairley and malaria, 1947) must be seen in the context of much detailed work of national relevance by institutions and individuals. The directions of Australian research can be related to several major themes: the large extent of Australia that is tropical or subtropical; interactions with neighbouring countries, especially Papua New Guinea; and concern for the health of Australian Aborigines.

Hepatitis B virus markers in children and staff in Northern Territory schools

OBJECTIVE

To measure the prevalence of hepatitis B virus (HBV) infection in children and staff at Northern Territory schools.

DESIGN

Children in Years 5-7 in 24 selected primary schools were invited, with parental consent, to provide demographic and ethnic details, and a capillary blood sample for tests for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs). School staff participated on a similar basis.

PARTICIPANTS

1104 children, comprising 556 from ethnic groups (originating from the United Kingdom, Ireland and northern Europe) previously reported as "low HBV prevalence", 439 Aboriginal Australians, and 109 from "other" ethnic groups (originating from Asia, the Pacific, the Middle East and southern Europe); and 209 school staff, comprising 180 from "low HBV prevalence" ethnic groups, and 29 from Aboriginal and other ethnic groups.

RESULTS

Prior HBV infection (i.e. serum positive for HBsAg or anti-HBs) was detected in 28.7% of children (46.9% of 439 Aborigines; 13.7% of the 556 children from the "low prevalence" groups and 32.1% of the 109 from the "other" groups). HBsAg was detected in 8.2% of Aboriginal children, in 0.36% of those from "low prevalence" groups, and in 1.8% of those from the "other" groups. Aboriginal children in rural schools had the highest prevalence of HBV: 5.4% were positive for both HBsAg and anti-HBs, and an additional 9.8% were positive for HBsAg alone. In urban schools, the prevalence was highest in the "other" ethnic groups. For school staff, the prevalence of HBV infection was 12.8% for those from "low prevalence" ethnic groups, and 37.9% for those from all remaining groups (including Aborigines).

CONCLUSION

In the Northern Territory the prevalence of past HBV infection is high in children and school staff from ethnic groups previously known to be at higher risk of HBV infection. For students and staff from ethnic backgrounds expected to be at low risk, HBV prevalence is greater than in individuals from similar backgrounds in other parts of Australia. HBV vaccination is now offered to all infants in the Northern Territory. These results also provide a rationale for the more widespread use of HBV vaccine in other situations where significant HBV transmission might occur.

Aboriginal health--current status

An analysis of the limited available data confirms that the health status of Australia's Aborigines remains much worse than that of non-Aboriginal Australians. Despite significant improvements over the past decade Aboriginal fetal and infant mortality is still approximately three times that of non-Aborigines. Aboriginal life expectancy remains at least twenty years less than that of the total Australian population. Levels of Aboriginal hospitalisation have declined markedly, but remain well in excess of overall levels, particularly for infants and children. For Aborigines, the reduced overall impact of the communicable diseases has been balanced by a worsening of the "lifestyle" diseases, particularly hypertension, coronary heart disease and diabetes mellitus. Alcohol abuse plays an important role in these diseases, and in the level of accidents and violence amongst Aborigines. The current patterns require a reassessment of Aboriginal health priorities, with more attention being directed at the health problems of Aboriginal adults. Special Aboriginal health programs need to be expanded, and integrated with broad wide-ranging programs aimed at alleviating Aboriginal social inequality.

Hepatitis and haemophilia therapy in Australia

243 Australian haemophiliacs have been studied retrospectively over 4 1/2 years to assess the effect of treatment products on liver function and to determine the frequency of hepatitis-B markers in these patients. Commercial blood products are not used in Australia, and the patients were treated with products of blood from unpaid donors screened for hepatitis B surface antigen. Cryoprecipitate was the major treatment product, and only small amounts of factor VIII and IX concentrates were used. Despite the use of blood products obtained from entirely voluntary blood donors and the frequent use of single-donor packs of cryoprecipitate, markers of viral hepatitis were common in these haemophiliacs. Antibody to hepatitis B surface antigen was detected in 63% of the patients, and there were 66 cases of non-A, non-B hepatitis during the study. 29 of these episodes persisted for longer than 6 months. 13 patients (5.4%) had hepatitis B during the study; 2 patients remained HBsAg-positive for longer than 6 months. Abnormal serum aminotransferase levels were found in 34% of the patients; in 8% of patients these abnormalities persisted for more than 6 months.

Hepatitis B in Australian Aborigines and Torres Strait Islanders: georgraphical, age and familial distribution of antigen subtypes and antibody

Hepatitis B antigen of subtype ay is prevalent in Australian Aboriginal populations, but only subtype ad was found in Torres Strait Islanders. Both subtypes were found in Caucasion hepatitis patients and blood donors from Brisbane. Antigenaemia in Aborigines was more prevalent in Northern Territory than in Queensland, and in males in all areas, but different age distributions were found in Queensland (maximal over 30 years) and Northern Territory (maximal under 30 years). Family clustering was striking in all populations where genealogies were known. In a limited survey antibody was found to be more common than antigen in all Aboriginal groups, the prevalence increasing with age with a peak at 11 to 30 years. Hepatitis B virus infection was equally common in some areas of high and low arbovirus activity providing some evidence against arthropod transmission of hepatitis B virus in these areas.