Perinatal transmission of hepatitis B virus in Kenya: its relation to the presence of serum HBV-DNA and anti-HBe in the mother

Systematic review with meta-analysis: the risk of mother-to-child transmission of hepatitis B virus infection in sub-Saharan Africa

BACKGROUND

The risk of mother-to-child transmission of hepatitis B virus (HBV) has been quoted as 70-90% among women positive for hepatitis B surface antigen (HBsAg) and e antigen (HBeAg), and 5-30% among HBsAg-positive HBeAg-negative women. These risks are derived from Asia; little is known about sub-Saharan Africa.

AIM

To determine the risk of mother-to-child transmission in sub-Saharan Africa, according to maternal HBeAg and type of prophylaxis.

METHODS

We searched Medline, Global Health, Embase, African Journals Online and African Index Medicus. We included observational or interventional studies that enrolled infants of HBV-infected women, and that tested for HBsAg or HBV DNA between 3 and 12 months of age.

RESULTS

Fifteen articles from 11 African countries were included. Among HBeAg-positive women, the pooled risk was 38.3% (95% CI: 7.0-74.4%) without prophylaxis, which was significantly lower than the lower bound of 70-90% risk in the literature (P = 0.007). Among HBeAg-negative women, the pooled risk was 4.8% (95% CI: 0.1-13.3%) without prophylaxis, which lays within the lower range of the 5-30% risk in Asia. By extrapolating the pooled transmission risks to the number of births to infectious mothers, an estimated 1% of newborns (n = 367 250) are annually infected with HBV at birth in sub-Saharan Africa.

CONCLUSIONS

Compared to Asia, the risk of mother-to-child transmission is low in sub-Saharan Africa. However, the annual number of infants perinatally infected with HBV is twice the number of incident paediatric HIV infections in sub-Saharan Africa (n = 190 000). This highlights the importance of preventing mother-to-child transmission of HBV in sub-Saharan Africa, which has been long neglected.

Hepatitis B virus sero-profiles and genotypes in HIV-1 infected and uninfected injection and Non-injection drug users from coastal Kenya

Background

Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive.

Methods

A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n = 157 and n = 214) and non-IDUs (n = 139 and n = 48), and HIV-1 uninfected non-drug using controls (n = 194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing.

Results

HBsAg positivity was higher in HIV-1 infected IDUs (9.6 %) relative to HIV-1 uninfected IDUs (2.3 %), HIV-1 infected non-IDUs (3.6 %), HIV-1 uninfected non-IDUs (0.0 %) and non-drug users (2.6 %; P = 0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6 %) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3 %), and non-IDUs (8.6 %), and non-drug users (8.2 %; P = 0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2 %) compared to HIV-1 uninfected IDUs (3.3 %), HIV-1 infected non-IDUs (6.5 %), HIV-1 uninfected non-IDUs (2.1 %) and non-drug users (4.6 %; P = 0.038). Acute (5.7 %, 1.4 %, 0.0 %, 0.0 % and 1.5 %) and chronic (5.1 %, 0.9 %, 3.6 %, 0.0 % and 1.5 %) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4 %) relative to HIV-1 infected IDUs (6.4 %), and HIV-1 infected (6.5 %), and uninfected (10.4 %) non-IDUs, and non-drug users (5.7 %; P = 0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2 %) compared to HIV-1 infected IDUs (8.3 %), and HIV-1 infected (7.2 %), uninfected (6.3 %) non-IDUs, and non-drug users (6.7 %; P = 0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants.

Conclusion

HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya.

Hepatitis B virus infection among HIV-infected pregnant women in Malawi and transmission to infants

BACKGROUND & AIMS

The extent of HBV infection to infants of HBV/HIV-coinfected pregnant women in sub-Saharan Africa is unknown. The aim of this study was to assess prevalence of HBV infection among antiretroviral-naïve, HIV-infected pregnant women in Malawi and examine HBV transmission to their infants.

METHODS

Plasma from 2048 HIV-infected, Malawian women and their infants were tested for markers of HBV infection. Study participants were provided standard-of-care health services, which included administration of pentavalent vaccine to infants at 6, 10, and 14 weeks of age.

RESULTS

One-hundred and three women (5%) were HBsAg-positive; 70 of these HBsAg-positive women were also HBV-DNA-positive. Sixteen women (0.8%) were HBV-DNA-positive but HBsAg-negative. Five of 51 infants (9.8%) born to HBsAg-positive and/or HBV-DNA-positive women were HBV-DNA-positive by 48 weeks of age.HBV DNA concentrations of two infants of mothers who received extended lamivudine-containing anti-HIV prophylaxis were <4 log10 IU/ml compared to ⩾ 8 log10 IU/ml in three infants of mothers who did not.

CONCLUSIONS

HBV DNA was detected in nearly 10% of infants born to HBV/HIV-coinfected women. Antenatal testing for HIV and HBV, if instituted, can facilitate implementation of prophylactic measures against infant infection by both viruses.

Genotyping and molecular characterization of hepatitis B virus in liver disease patients in Kenya

Hepatitis B virus (HBV) genotypes are important in both the clinical manifestation of disease and treatment response. Although Kenya belongs to the African Region (AFR-E) characterized by high mortality and hyperendemicity of HBV, there is a paucity of HBV genotyping data. The aim of this study was to molecularly characterize the basic core promoter/precore (BCP/PC) and complete surface (S) regions of HBV isolated from 61 HBsAg-positive liver disease patients attending Kenyatta National Hospital in Nairobi. HBsAg, HBeAg and viral loads were determined. HBV DNA was amplified and sequenced from 58/61 patients. In addition to the complete genome of two isolates, the BCP/PC and the complete S regions of 43 and 38 isolates, respectively were sequenced. Following phylogenetic analysis of the S region, 38 isolates clustered with subgenotype A1, whereas two isolates clustered with genotype D, one with subgenotype D1 and another as an outlier of the clade containing subgenotype D6 and the D/E recombinant. When the complete genome of the latter isolate was sequenced it clustered with D6. The majority of isolates belonged to serological subtype adw2 and only four to ayw2. Three distinct groups of subgenotype A1, distinguished by different amino acid motifs, circulate in Kenya: two in the African cluster and a monophyletic clade in the "Asian" cluster. HBeAg-negativity was a result of G1896A in genotype D isolates, whereas in subgenotype A1, the HBeAg-negativity was a result of mutations in the Kozak region (1809-1812) or precore start codon (1814-1816). Mutations at positions 1762 and 1764 occurred more frequently in HCC patients (p<0.05). In conclusion, subgenotypes A1, D1 and D6 circulate in liver disease patients in Kenya, with A1 predominating.

Maternofetal transmission of hepatitis B virus genotype E in Ghana, west Africa

To determine whether maternofetal transmission of hepatitis B virus (HBV) is a common route of infection leading to chronic infection in west Africa, plasma samples, obtained at delivery from 1368 pregnant Ghanaian women and paired umbilical cord blood or newborn whole blood samples, were tested for HBV surface antigen (HBsAg) and DNA. A 16 % prevalence of HBV chronic carriers, defined as detectable HBsAg and/or HBV DNA, was found, >80 % contained less than 1 x 10(4) IU ml(-1) HBV DNA and 99 % were infected with genotype E strains. HBV maternofetal transmission was documented in 17 out of 204 (8.3 %) paired HBV carrier women-cord blood/newborn samples. The rate of transmission was 55 % and 3.3 % when maternal viral load was above or below 1 x 10(4) IU ml(-1), respectively (P=0.0008). Maternofetal transmission of HBV genotype E was estimated to account for 8 % of the cases of chronic HBsAg carriers. Six women with low viral load at delivery (five <20 IU ml(-1)) and anti-HBe (hepatitis B e antigen) transmitted HBV. Surprisingly, while non-transmitted low viral load strains had 79 % mutations at position 1896 of HBV genome, transmitted strains were all wild-type despite anti-HBe presence (P=0.0041), suggesting the possible role of HBeAg as risk factor for HBV maternofetal transmission. The relative risk of maternofetal transmission was 2.4 when pregnant women carried high viral load and 11.5 when carrying wild-type strains at position 1896, irrespective of viral load. We conclude that viral load and pre-core wild-type at position 1896 are two independent risk factors for HBV genotype E maternofetal transmission, which remains a minor contributor to high prevalence of chronic infection.

Epidemiological patterns of hepatitis B virus (HBV) in highly endemic areas

This paper uses meta-analysis of published data and a deterministic mathematical model of hepatitis B virus (HBV) transmission to describe the patterns of HBV infection in high endemicity areas. We describe the association between the prevalence of carriers and a simple measure of the rate of infection, the age at which half the population have been infected (A50), and assess the contribution of horizontal and perinatal transmission to this association. We found that the two main hyper-endemic areas of sub-Saharan Africa and east Asia have similar prevalences of carriers and values of A50, and that there is a negative nonlinear relationship between A50 and the prevalence of carriers in high endemicity areas (Spearman's Rank, P = 0.0086). We quantified the risk of perinatal transmission and the age-dependent of infection to allow a comparison between the main hyper-endemic areas. East Asia was found to have higher prevalences of HBeAg positive mothers and a greater risk of perinatal transmission from HBeAg positive mothers than sub-Saharan Africa, though the differences were not statistically significant. However, the two areas have similar magnitudes and age-dependent rates of horizontal transmission. Results of a simple compartmental model suggest that similar rates of horizontal transmission are sufficient to generate the similar patterns between A50 and the prevalences of carriers. Interrupting horizontal transmission by mass immunization is expected to have a significant, nonlinear impact on the rate of acquisition of new carriers.

Familial clustering of hepatitis B virus infections and prevention of perinatal transmission by immunization with a reduced number of doses in an area of intermediate endemicity (Tunisia)

Hepatitis B surface antigen (HBsAg) was detected in 3.3% of 7162 pregnant Tunisian women tested and HBeAg in 9.6% of the HBsAg-positive mothers. Family members of 46 of these HBsAg-positive mothers (33 husbands and 61 children aged 1-6 years) were investigated for the presence of HBV markers. HBsAg was detected in 21% of the children and 18% of the husbands. Fifty children born to HBsAg-positive mothers received hepatitis B vaccine at birth, at the age of 2-3 months and at the age of 9 months. After immunization, anti-HBs were detected in 92% of them with an anti-HBs geometric mean titre of 415 mIU ml-1. Compared with the HBsAg carrier state in older siblings, the protective efficacy was estimated to be 60%. It was 100% for infants born to HBeAg-negative mothers, but only 31% for those born to HBeAg-positive mothers. For a better efficacy, the schedule of the EPI needs to be modified to include an immunization session at 1 month of age.

Population-based study of serum hepatitis B virus DNA in Gabon

The prevalence of serum hepatitis B virus (HBV) deoxyribonucleic acid (DNA) was measured in a Gabonese community at high risk for HBV infection. Among 698 subjects 5 to 24 years old, the prevalence of HBsAg was 11.1% vs. 57.9% for anti-HBs and 7.2% for anti-HBc alone. The prevalence of HBeAg among HBsAg-positive subjects was 26.5% vs. 59.5% for anti-HBe. The prevalence of HBV DNA tested by a hybridization spot test was 2.1% in the overall population and 18.7% among HBsAg-positive subjects. HBV DNA was found in 15 of 21 HBeAg-positive subjects but in none of the subjects positive for anti-HBe or negative for both HBeAg and anti-HBe. HBV DNA was not detected in any HBsAg negative subjects. The prevalence of HBV DNA decreased with age. This low prevalence of HBV DNA contrasts with the high level of endemicity in the study population.

Cost-benefit analysis of a nationwide neonatal inoculation programme against hepatitis B in an area of intermediate endemicity

STUDY OBJECTIVE

The aim was to estimate the costs and benefits of a nationwide neonatal vaccination campaign against hepatitis B in Israel for the 1990-2034 period.

DESIGN

Using morbidity, mortality, utilisation, and cost data from Israeli and international sources, a spreadsheet model was constructed to carry out the cost-benefit analysis.

SETTING

The entire State of Israel, an area of intermediate endemicity.

PARTICIPANTS

The population of Israel from 1990-2034.

MAIN RESULTS

A policy of immunising all Israeli neonates would, for a cost of $13.8 million, reduce the number of cases of hepatitis B during the 1990-2035 period in the cohort from 359,000 to 166,000 and save the nation around $21.5 million in health resources alone, $16.6 million in averted work absences, and a further $0.6 million in averted premature mortality costs. Even when the savings to the health services ($0.6 million) arising from the reduction in hepatocellular carcinoma are excluded, the direct benefit to cost ratio is 1.51/1, still in excess of unity.

CONCLUSIONS

The decision to adopt a nationwide neonatal inoculation policy, starting in January 1992, appears to be not only medically but also economically justifiable.

Intrafamilial clustering of hepatitis B virus (HBV) infection: study of 10 Saudi families

In order to evaluate the extent of intrafamilial clustering of hepatitis B virus (HBV) infection, serological tests for evidence of HBV infection were performed on family members of 10 Saudi children who were found to be HBs Ag-positive. The overall prevalences of carriers (HBs Ag-positive) and exposure (presence of any HBV marker) in the 89 siblings were 17.9 and 34.8%, respectively. In siblings of families where the mother was a carrier, exposure to HBV (51.6%) was higher (chi 2 = 1.99, P = 0.15) than in siblings of families where only the father was a carrier (31.4%) and significantly higher (chi 2 = 5.24, P = 0.02) than in siblings of families where neither of the parents was a carrier but both had previous exposure to HBV infection (17.4%). Our data indicate that mainly horizontal and perhaps perinatal transmission could account for this relatively high level of intrafamilial clustering of HBV infection in Saudi families. These results are important for the development of a strategy for controlling HBV infection in Saudi Arabia and perhaps in similar HBV endemic areas.

Combined immunoprophylaxis in the prevention of perinatal transmission of hepatitis B and hepatitis D virus infections in Saudi children

The efficacy of the combined immunoprophylaxis approach (passive plus active immunization) was evaluated in babies born to 52 HBsAg-carrier Saudi mothers, of whom seven (13.5%) were HBeAg-positive and seven were anti-HDV-positive. Newborns were given 100 IU of hepatitis B immune globulin (HBIG) from the Hepuman Berna-Swiss Serum and Vaccine Institute, Berne, and hepatitis B vaccine (5 micrograms) within 12 hours of birth, and the vaccine was given again at 1 and 6 months of age (5 micrograms/injection). After 18 months of follow-up, all but one baby had protective levels of antibody to HBsAg and none of the babies born to anti-HDV-positive carrier mothers showed evidence of HDV infection. These results show that the combined immunoprophylaxis approach is quite successful in protecting against perinatal transmission of HBV and HDV in the Saudi population. Furthermore, early vaccination against HBV will also protect against HDV infection later in life.

Epidemiology of hepatitis B in eastern Kenya

A cross-sectional survey of outpatients attending the three distinct hospitals in the towns of Mombasa, Kilifi, and Malindi was conducted to determine the patterns of hepatitis B transmission in eastern Kenya. Of 1,533 study subjects (mean age 21.9 +/- 13.2 years; range, 4 months to 80 years), 11.4% were positive for HBsAg and 56.2% were seropositive for at least one hepatitis B marker (HBsAg, anti-HBs, or anti-HBc). Anti-delta antibody was found in 1.2% of HBsAg-positive samples. HBeAg was found in 36.0% of HBsAg-positive samples obtained from women of childbearing age. The prevalence of seropositivity for hepatitis B markers was positively correlated with age, increasing from 20% in subjects less than 4 years old to more than 80% in study subjects greater than 40 years old. On multivariate analysis, male sex was found to be associated with HBsAg positivity, and age and previous deliveries of children were associated with seropositivity for any hepatitis marker (HBsAg, anti-HBs, or anti-HBc). An effective hepatitis B immunization strategy in this region of Kenya would require vaccination early in life because a major portion of hepatitis B transmission occurs in childhood.

Lack of evidence for transplacental transmission of HBV infection by HBsAg-carrier mothers

The possibility of transplacental transmission of HBV infection was investigated in 54 HBsAg-carrier Saudi mothers and their newborns. Controls were 60 Saudi mothers with previous exposure to HBV, and their newborns. Thirteen cord blood samples were HBsAg-positive by ELISA, including three from mothers with previous exposure to HBV, compared with one sample which was HBsAg- and HBeAg-positive and three samples which were only HBeAg-positive. Eight of the 13 cord blood samples which were HBsAg-positive by ELISA were haemolysed sera and were found to be HBsAg-negative by RIA and RPHA. None of the infants' sera, taken within 1-4 days of delivery, was positive for HBsAg or IgM anti-HBc. These results indicate that HBV markers in cord blood are either false-positive or due to contamination by maternal blood rather than an indication of in utero infection.

Hepatitis B surface antigen associated nephrotic syndrome

Hepatitis B virus (HBV) has been reported in association with the nephrotic syndrome from different parts of the world, but its role as a cause of the pathological findings of nephrotic syndrome is still controversial. We report seven nephrotic children with positive hepatitis B markers in which members of their families were also positive for the markers but without clinical, renal or hepatic involvement. Four showed haematuria at onset and three developed hypertension later in the course of the disease. Only two were responsive to steroid therapy. Renal biopsy was performed in four, of whom three showed membranous nephropathy and the other showed mesangioproliferative glomerulonephritis. Four patients developed end-stage renal disease. We conclude that in our environment HBV, when detected in children with nephrotic syndrome, should not be considered as a chance finding, but may have a definite role in its pathogenesis. Moreover, the prognosis of HBV-associated nephrotic syndrome appears poor.

Absence of maternal antibodies to hepatitis B core antigen and HBV vertical transmission: one case of infection notwithstanding passive-active prophylaxis

We report the case of a newborn of an HBsAg carrier mother who was infected by vertical transmission and developed a subclinical hepatitis B at four months of age, notwithstanding the passive-active prophylaxis performed right after birth. The mother's HBV marker status was: HBsAg positive, HBeAg positive, anti-HBc IgM positive at low titer, anti-HBc IgG negative, anti-HBs negative, anti-HBe negative. It is assumed that the absence of anti-HBC antibodies might have favoured, perhaps in utero, the HBV infection whose antigenic expression was subsequently delayed by HBIg administered at birth. These findings suggest that the positivity for anti-HBc IgM must be considered an additional marker of maternal infectivity especially in the absence of anti-HBc IgG antibodies.