Hepatitis B, tropical ulcers, and immunisation strategy in Kiribati

Progress towards hepatitis B prevention through vaccination in the Western Pacific, 1990-2014

Hepatitis B infections are responsible for more than 300 thousand deaths per year in the Western Pacific Region. Because of this high burden, the countries and areas of the Region established a goal of reducing hepatitis B chronic infection prevalence among children to less than 1% by 2017. This study was conducted to measure the progress in hepatitis B prevention and assess the status of achievement of the 2017 Regional hepatitis B control goal. A literature review was conducted to identify studies of hepatitis B prevalence in the countries and areas of the region, both before and after vaccine introduction. A mathematical model was applied to assess infections and deaths prevented by hepatitis B vaccination and hepatitis B prevalence in countries without recent empirical data. The majority of countries and areas (22 out of 36) were estimated to have over 8% prevalence of chronic hepatitis B infection among persons born before vaccine introduction. After introduction of hepatitis B vaccine, most countries and areas (24 out of 36) had chronic infection prevalence of less than 1% among children born after vaccine introduction. It was estimated that in the past 25 years immunization programmes in the Western Pacific Region have averted 7,167,128 deaths that would have occurred in the lifetime of children born between 1990 and 2014 if hepatitis B vaccination programmes had not been established. Regional prevalence among children born in 2012 was estimated to be 0.93%, meaning that the Regional hepatitis B control goal was achieved. While additional efforts are needed to further reduce hepatitis B transmission in the region, this study demonstrates the great success of the hepatitis B vaccination efforts in the Western Pacific Region.

Molecular epidemiology of hepatitis delta virus in the Western Pacific region

BACKGROUND

Hepatitis delta virus (HDV) is a defective RNA virus requiring the presence of the hepatitis B virus (HBV) for the completion of its life cycle. Active replication of HDV can lead to severe hepatitis, and although present worldwide has an irregular geographical distribution, especially in the Asian Pacific region.

OBJECTIVES

The aim of this study was to determine the prevalence and molecular epidemiology of HDV isolates in Oceania following the 1998 evaluation of the hepatitis B vaccine program.

STUDY DESIGN

Sera collected from 184 hepatitis B surface antigen (HBsAg) positive Pacific Islanders living in Micronesia, Polynesia and Melanesia were tested for HDV RNA.

RESULTS

Twenty of 54 patients with chronic hepatitis B (CHB) from Kiribati were positive for serum HDV RNA (37%), whilst sera from patients with CHB from Tonga (59), Fiji (42) and Vanuatu (29) were negative. The mean HDV RNA load for the 20 samples was 7.00log10copies/mL. Phylogenetic analysis revealed that the Kiribati HDV isolates were of genotype 1 and clustered with a previously published isolate from Nauru forming a distinct clade of Pacific HDV. All Micronesian isolates contained a serine at codon 202 of large hepatitis delta antigen (L-HDAg) demonstrating possible relatedness to strains of HDV-1 of African origin.

CONCLUSIONS

This study has confirmed endemic HDV infection in Micronesia and identified Kiribati as having amongst the highest prevalence for HDV viraemia in patients with CHB. Further investigations are ongoing into the origins of this unique HDV Pacific strain, and its inter-relationship with HBV.

Tattooing and transfusion-transmitted diseases in Brazil: a hospital-based cross-sectional matched study

BACKGROUND

Presence of tattoos has been a criterion for temporary deferral of blood donors. Scientific evidence remains equivocal regarding the association between tattooing and transfusion-transmitted diseases (TTDs).

METHODS

A cross-sectional matched study was undertaken among adults attending a Brazilian hospital and blood bank. The exposure of interest was having at least one permanent tattoo, and the outcomes were the presence of serological markers for the following TTDs: hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections, syphilis, and Chagas' disease. Exposed and unexposed subjects were matched on age, sex, and main clinical complaint. Associations were assessed by odds ratios (ORs), adjusted for confounders by unconditional logistic regression.

FINDINGS

The study recruited 345 subjects, 182 with tattoos. Having a tattoo was associated with HCV (OR: 6.41; 95% confidence interval (CI) 1.29, 31.84), and with having at least one positive test for any TTD (OR: 2.05, 95% CI: 1.11, 3.81). No statistically significant associations were found between tattooing and HBV or HIV infection, syphilis or Chagas' disease, but these results are inconclusive given the large CI obtained.

INTERPRETATION

Having a tattoo is not an important indicator for testing positive for a TTD, except for HCV infection. Taking into consideration the increasing prevalence of tattooing in the general population, the absolute need of a safe and sustainable blood supply and optimization of the cost-effectiveness of screening blood donors, further research on tattoos is urgently required.

Tropical ulcers: a condition still hidden from the western world

Tropical ulcers cause great pain and often lead to terrible deformities and amputations among very poor patients. Theories exist about their cause and treatments, but this literature review shows an urgent need for more research into this Cinderella area.

Tattoos as risk factors for transfusion-transmitted diseases

BACKGROUND

Several infectious diseases have been found to be associated with tattooing, including some transfusion-transmitted diseases (TTDs). Information on tattooing has been included in screening interviews of prospective blood donors and may be a reason for deferral.

METHODS

Review of articles identified through Medline (and other computerized data bases) using medical subject heading (MeSH) terms and textwords for "tattooing," "transfusion", "hepatitis", "human immunodeficiency virus", "acquired immunodeficiency syndrome", "syphilis", "Chagas disease", "infection", "risk factors", and their combinations.

RESULTS

There is strong evidence for the transmission of hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, and syphilis by tattooing. Tattooing may also transmit the human immunodeficiency virus (HIV), although convincing evidence is still lacking. There is little or no evidence that other TTDs can be transmitted by tattooing. Epidemiologic studies to date have shown a large variation in odds ratio estimates of the association between tattooing and HBV, HCV, and HIV infections.

CONCLUSION

Further studies are required to clarify the risk of tattoos in transmitting infectious diseases through blood transfusions. A reassessment of tattoos as a screening criterion among blood donors is justified.

The investigation of a 'cluster' of hepatitis B in teenagers from an indigenous community in North Queensland

BACKGROUND

In early 1999, five teenagers from the same Indigenous community were notified as having hepatitis B. Hepatitis B vaccine should have been offered to this cohort of teenagers in a 'catch-up' program during the late 1980s when they were of pre-school age.

OBJECTIVES

To determine the vaccination status of residents of the community born between 1981 and 1985 (inclusive) and to ascertain the prevalence of markers of hepatitis B infection and carriage in the incompletely vaccinated teenagers in this cohort.

METHODS

Community health records were examined to identify all residents in the study cohort. Immunisation records were obtained from local hospital records and from a statewide computerised vaccination database. Serological tests for markers of hepatitis B infection and carriage were performed on blood samples from the incompletely vaccinated teenagers.

RESULTS

Only 44% of 235 teenagers who had their vaccination status assessed were fully vaccinated. One hundred and eleven (47%) of the cohort had not received any hepatitis B vaccine. Over 90% of the incompletely vaccinated had been infected with the hepatitis B virus and 26% of these were hepatitis B carriers.

CONCLUSIONS

Despite the availability of an effective hepatitis B vaccine and the recommendation for a catch-up program, the pre-school aged cohort of children at the community were not effectively targeted for vaccination. Hepatitis B remains a consequential infection in Indigenous communities in North Queensland.

IMPLICATIONS

Initiatives to control hepatitis B need to be enhanced within existing maternal and child health, sexual health, alcohol and drug and chronic disease management programs.

Tropical aspects of viral hepatitis. Hepatitis C

This paper reviews our current understanding of hepatitis C infection in tropical countries. Since its discovery in 1989, hepatitis C has been recognized as an important disease in many tropical countries. In Egypt the prevalence in some sections of the population may-exceed 20%. In most tropical areas, however, the epidemiology of hepatitis C infection is poorly defined. There are clear variations in the distribution of genotypes in different areas and this may be one of the factors which influence the natural history of infection in different regions of the world. Routes of infection in tropical countries are poorly defined, most carriers having no clear risk factors for infection. There is some speculation that inadequate sterilization of medical equipment may be a route of infection in some areas. A combination of factors may result in an increased risk of hepatocellular carcinoma developing in patients from the tropics infected with hepatitis C and the prognosis may be worse due to co-infection with hepatitis B and human immunodeficiency virus, both of which may lead to accelerated liver disease. Prospects for disease control are poor due to the difficulty of developing a vaccine to the virus.

Acute hepatitis B infection in aboriginal Australians

The apparent incidence of acute hepatitis B infection in the Top End of the Northern Territory was estimated from notification data and hospital data to be 12 per 100,000 per year, with a marked difference between Aborigines (42 per 100,000) and non-Aborigines (4 per 100,000), and an odds ratio of 9.7 (95 per cent confidence intervals 3 to 33). Sixty percent of Aboriginal cases of acute hepatitis B occurred in children under 10 years of age, whereas non-Aboriginal cases occurred in adults aged 20 to 29, most with behavioural risk factors. These findings confirm the importance of immunising Aboriginal children to reduce the future incidence of hepatitis B infection and hepatoma.

Hepatitis B in urban Australian schoolchildren. No evidence of horizontal transmission between high-risk and low-risk groups

OBJECTIVE

To document the prevalence of hepatitis B virus (HBV) infection in urban Australian primary schoolchildren, and to look for evidence of horizontal transmission of HBV in schools between children at high risk of infection and those at low risk. We compared the prevalence of infection in a group of low-risk children attending control schools (less than 5% of students from high-risk groups) with the prevalence in low-risk children attending test schools (more than 20% of students from high-risk groups).

METHODS AND RESULTS

Venous blood was collected and tested for hepatitis B markers by radioimmunoassay; 2883 children (1431 boys) of mean age 11.3 years (SD, 0.7) from 50 schools were tested. Evidence of past or current infection was present in 169 children (5.9%). This number comprised three of the 1347 low-risk children (0.2%), 10 of the 602 medium-risk children (1.7%), 154 of the 731 high-risk children (21.1%) and two of the 203 other children (1%). Fifty-four of the 169 infected children were hepatitis B surface antigen (HBsAg) positive, 36 of the 54 were also positive for hepatitis B e antigen (HBeAg). There was no difference between children in the low-risk group in test and control schools for markers of hepatitis B virus infection.

CONCLUSIONS

A low prevalence of HBV infection was found in low-risk school-children irrespective of the proportion of high-risk children in their classes. Targeting vaccination to infants and children with known risk factors is the most important strategy in low endemicity countries; vaccination of children without risk factors could be delayed till early adolescence.

Sex ratios at birth in a Micronesian Atoll population

The recent suggestion that typically masculinized sex ratios at birth in Micronesian populations may be related to a distinct "Micronesian pattern" of life-course coital behavior is applied to data on the sex ratio of livebirths on Butaritari Atoll in Kiribati. The data show that sex ratios on Butaritari are highly masculinized and do not vary significantly with changes in maternal age. However, there is a discernible relationship between the length of closed intervals preceding male and female births. The lack of age-related change in sex ratios in the Butaritari sample is inconsistent with ethnographic data regarding levels of marital coital activity in relation to increasing age and marriage duration. The Butaritari sex ratio data is argued to support the suggestion of a "Micronesian pattern," although it is posed that further tests of this association are required.

Age-specific prevalence of hepatitis B surface antigenaemia in hospitalized children at Port Moresby, Papua New Guinea (a cross-sectional study with implications for the Hepatitis B Control Programme)

A cross-sectional analysis of the prevalence of hepatitis B surface antigenaemia in cord blood from 50 newborn babies and in blood from 415 children admitted to the children's ward of Port Moresby General Hospital indicates that perinatal vertical transmission is likely to be important and that there is a high rate of horizontal transmission in the 1st few years of life. Thirteen per cent of infants aged 3-5 months and 29-30% of those over 2 years of age were strongly positive for hepatitis B surface antigen. Open sores and poor hygiene are likely to play a significant role in the high level of horizontal transmission of hepatitis B virus (HBV) in our context. Our findings give support and urgency to the current active immunization policy against HBV, beginning as soon as possible after birth.

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.

Prevalence of hepatitis C in tropical communities: the importance of confirmatory assays

The prevalence of antibody to hepatitis C virus (HCV) was estimated in 3 tropical populations using 2 screening ELISAs to detect antibody to the c100-3 antigen and 2 supplementary assays designed to test the specificity of these tests. Two hundred and eighty-six of 385 (74.2%) sera from Kiribati, 17 of 138 (12.3%) sera from Vanuatu, and 39 of 173 (22.5%) sera from Zaire were reactive in the initial screening assay. The proportion of reactive sera which were also reactive in the second screening ELISA varied between populations (55.1% in Kiribati, 85.1% in Vanuatu, and 39.2% from Zaire). Reactive sera were selected at random for confirmatory testing. Only 3 of 49 (6.12%) of sera from Kiribati and 1 of 14 (4.76%) of sera from Vanuatu positive in the initial ELISA were reactive in the confirmatory assays. The proportion of confirmed positive sera from Zaire was higher 8 of 28 (28.5%). Based on the results of these supplementary assays the estimated prevalence of anti-HCV in these populations is 4.8% in Kiribati, less than 1% in Vanuatu, and 6.4% in Zaire. Reliance on a single screening ELISA to estimate the prevalence of anti-HCV in stored sera from tropical communities may lead to a gross over-estimate of the true prevalence in these populations.

The hepatitis B virus

Of all the hepatotropic viruses, HBV is associated with the greatest worldwide morbidity and mortality. This is because of the ease of transmission and the potential for progression to a chronic infective carrier state, with the complications of cirrhosis and hepatocellular carcinoma. The use of PCR has shown that some of the earlier concepts concerning the interpretation of serological data were inaccurate. Many patients with anti-HBe and anti-HBs have viral DNA detectable by PCR, and some hepatocellular carcinoma patients have detectable HBV DNA in their livers in the absence of all serological markers of HBV disease. The clearance of HBV infected cells from the liver is dependent on the interplay between the interferon system and the cellular limb of the host immune response. The importance of the nucleocapsid proteins as targets for sensitized cytotoxic T cells has been established for chronic HBV infection. The importance of pre-S sequences as inducers and targets of the virus-neutralizing humoral immune response is becoming established, but their precise role must await the development of in vitro models of hepadnavirus infection and a greater understanding of the mechanisms of viral uptake. The epidemiology and clinical course of the disease can be modified by immunization, immune stimulation and antiviral chemotherapy. For the developing world, a programme of immunization at birth would be the most effective way of eliminating this disease, but at present the cost is prohibitive. For the developed world, immunization is realistic for the at-risk population, and anti-viral and immunostimulatory therapy available for those already infected. In adult acquired chronic HBV infection alpha-interferon produces HBe antigen clearance in 40-60% of cases and is followed by resolution of the hepatic inflammation. Results in neonatally acquired infection are less impressive and prednisolone priming followed by interferon may be needed. The presence of a mutation in the pre-core region of some virus isolates has recently been described. Hepatocytes infected with this virus cannot produce HBe antigen and the course of the liver disease is fairly rapid. Whether this mutant causes liver damage in the same way as the wild virus or is directly cytopathic remains unclear, and its relationship to fulminant hepatitis is under investigation.

Delta hepatitis in Kiribati: a pacific focus

From the Pacific Republic of Kiribati, 90/130 (69%) of hepatitis B-infected individuals carry antibodies to hepatitis delta virus. The prevalence of delta infection varied between geographically isolated subgroups in the population and delta antibodies were found more frequently in subjects over the age of 10. It is unlikely that delta superinfection in this population is associated with an acute hepatic illness. The prevalence of delta infection is the highest recorded from the Pacific region and thus migrants from Kiribati may have provided the source of infection in other population in this region.

Control of HBV and HDV infection in an isolated Pacific Island: 1. Pattern of infection

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) infections are known to be hyperendemic in Nauru. Because of the consequences of chronic HBV infection, the Nauruan Government has commenced a program that aims to reduce and eventually eliminate hepatitis B infection by immunizing susceptible adults and children on the island and every newborn baby. At the outset of this program, a national seroepidemiological survey was undertaken. Eighty-eight percent of the population were tested, of whom 69.1% had markers of HBV infection. Evidence of superinfection with HDV was found in 22.7% of HBV carriers, with the highest prevalence in adolescents and young adults. All seronegative individuals were offered three doses of plasma derived hepatitis B vaccine. A post-vaccination survey of 64% of those vaccinated showed that 98% had developed circulating antibodies.

Hepatitis B infection in Vanuatu: age of acquisition of infection and possible routes of transmission

Seroepidemiological studies of hepatitis B were carried out on diverse groups of children (477) and adults (629) from the Pacific Island country of Vanuatu. In children under 14 years, prevalences of HBsAg and of all markers were 6% and 53.3% respectively; in adults greater than or equal to 20 years the prevalences were 15% and 70%. Age specific prevalence of hepatitis B infection (all markers) was low in infancy (less than 1 year) but rose sharply afterwards, suggesting that the main mechanism of transmission was horizontal spread. This finding is consistent with other developing country studies from the Pacific Islands and elsewhere. In view of the main ages and mechanisms of transmission of hepatitis B in children in developing countries and the need for simple and inexpensive immunisation strategies in this context, it is recommended that mass vaccination of all infants with hepatitis B vaccine be undertaken in hyperendemic areas.