Does the spread of hepatitis B virus genotype A increase the risk of intrafamilial transmission in Japan?

A case of child-to-father transmission of hepatitis B virus in Japan: a rare infection route

This report describes a rare horizontal transmission of hepatitis B virus (HBV) from an unvaccinated 6-year-old boy to his father. The father had been diagnosed with acute hepatitis B 1 month earlier; therefore, when the child visited the clinic with fever, he was screened for HBV markers and diagnosed as an asymptomatic carrier. Neither the child nor his father was vaccinated against HBV, whereas the child's mother and sister, having received the HBV vaccination as they were medical staff and a nursing student, respectively, tested negative for the hepatitis B surface antigen (HBsAg) and positive for anti-HBs. We performed a phylogenetic analysis of HBV in the child and his father, and identified 100% homologous strains of identical genotype C. At diagnosis, the father tested positive for IgM anti-hepatitis B core with a high titer, whereas the child tested negative for this marker. These data strongly indicated a child-to-father transmission. In this case, the HBV infection route was speculated as close contact including saliva-based transmission between the child and father, mainly attributed to their daily food habits. When clinicians diagnose patients with acute or chronic HBV infection, the household members should have been examined for HBV markers immediately. If some household members are susceptible to HBV infection, all members should be vaccinated against HBV.

Transmission route and genotype of chronic hepatitis B virus infection in children in Japan between 1976 and 2010: A retrospective, multicenter study

AIM

The aim of this study was to clarify the trends of the infectious source of chronic hepatitis B virus (HBV) infection and the HBV genotype in the Japanese pediatric population over the last three decades.

METHODS

The present study was a retrospective, nationwide, multicenter study. Patients who were under 20 years of age when diagnosed with chronic HBV infection were eligible for enrollment in this study. A total of 430 patients (male/female, 256/174; age at the time of writing, 1-37 years; median age, 14 years; birth year, 1976-2010) from 11 hospitals were evaluated.

RESULTS

The incidence of chronic HBV infection from 1976 to 1980, 1981-1985, 1986-1990, 1991-1995, 1996-2000, 2001-2005 and 2006-2010 was 56, 52, 34, 37, 81, 92 and 78, respectively. Of the 430 patients, 304 (71%), 61 (14%), 11 (3%) and 54 (13%) were infected via mother-to-child transmission, close contact, blood transfusion and unknown source, respectively. After the introduction of perinatal immunoprophylaxis, the rate of mother-to-child transmission increased from 62% during the 1991-1995 period to 86% during the 2006-2010 period. The distributions of genotypes A, B, C, D and F were 3%, 9%, 86%, 2% and 1%, respectively. No obvious change was observed in the distribution of genotypes. Genotype C was significantly associated with mother-to-child transmission.

CONCLUSION

Mother-to-child transmission remains the primary source of chronic HBV infection after the introduction of immunoprophylaxis. Taking measures to prevent immunoprophylaxis failure is essential to reduce pediatric chronic HBV infection in Japan.

Tackling the Hepatitis B Disease Burden in India

Globally, approximately 240 people have been infected worldwide with hepatitis B Virus (HBV). India has approximately HBV carrier rate of 3.0% with a high prevalence rate in the tribal population. With a population of more than 1.25 billion, India has more than 37 million HBV carriers and contributes a large proportion of this HBV burden. While horizontal transmission in childhood appears to be a major route of transmission, the role of vertical transmission is probably underestimated. Blood transfusion and unsafe therapeutic injections continue to be important modes of transmission of HBV. There is a need for large field studies to better understand HBV epidemiology and identify high prevalence areas, and public health measures to prevent disease transmission and decrease the burden of the disease.

A pediatric case of hepatitis B virus subgenotype A2 in Japan

Hepatitis B virus (HBV) has been classified into 10 major genotypes, and HBV genotypes C and B are found in the majority of Japanese patients. However, the prevalence of genotype A has been increasing in patients with chronic or acute hepatitis. Here we report a pediatric case of HBV subgenotype A2. A 2-year-old girl was referred to our hospital for liver damage caused by HBV infection. During the pregnancy, her father had developed acute sporadic hepatitis B. The child was born without any complications. She did not receive HBV vaccination at birth because her mother was negative for HBs antigen at the pre-delivery screening; however, her mother developed acute hepatitis B 2 months after delivery. At that time, HBs antigen was detected in the current patient. Phylogenetic full-length sequence analysis revealed HBV subgenotype A2. HBV sequencing was not performed for her parents; therefore, the intrafamilial transmission routes in these cases are unclear, although the authors speculate that, for the current patient, mother-to-child transmission may have occurred. This report illustrates the pitfalls of the selective vaccination strategy in Japan for preventing HBV infection. Universal vaccination to prevent HBV infection might be useful in Japan.

Causes of vertical transmission of hepatitis B virus under the at-risk prevention strategy in Japan

The number of hepatitis B virus (HBV) carrier babies has decreased markedly since the introduction in Japan of an "at-risk" strategy for preventing HBV infection. However, elimination of HBV infection from our country appears difficult. To clarify the limitations of the at-risk strategy for preventing vertical transmission of HBV, causes of vertical transmission in a single hospital were retrospectively analyzed. The following causes were presumed in 17 carrier pediatric cases: five patients had prenatal HBV infection, HBV infection during/after the immunization program was confirmed in five cases, two patients had prenatal infection or infection during the immunization program and three cases were caused by human error (by the patients' guardians). Because their mothers were HBV-negative at screening and only developed acute hepatitis B in the perinatal period, another two cases (Cases 3 and 10) did not undergo immunization because they were not subjects of the at-risk strategy. Sequence analyses in ten patients revealed genotype C (subgenotype, C2/Ce) in nine cases and genotype A (subgenotype, A2/Ae) in one case (Case 3). In Japan, HBV subgenotype Ae has recently been found more frequently among sexually active men with acute hepatitis. There are concerns that horizontal transmission of HBV from these men to their pregnant partners could increase. These data suggest clear limitations to the at-risk strategy in Japan and the possibility that the increase in genotype A may influence vertical transmission of HBV.

Lower intrafamilial transmission rate of hepatitis B in patients with hepatitis d coinfection: a data-mining approach

BACKGROUND

The presence of an infected family member significantly increases the risk of HBV transmission, but many socio-demographic and viral characteristics of family members affect the transmission rate.

OBJECTIVES

In this study, we have used data mining techniques to investigate the impact of different variables in intrafamilial transmission of HBV infection.

PATIENTS AND METHODS

demographic information, viral markers, and medical history of 330 patients with chronic hepatitis B and their offspring attending a referral center in Tehran were collected. Data-mining techniques were administered to detect patterns.

RESULTS

The overall transmission rate was 15.7% (5.4% and 27.3% for male and female index cases respectively). In female patients, HBe Ag positively affected the transmission rate (49% vs. 23.4%). There was a dominant change in transmission rate of female patients with negative results for Hbe Ag with HDV coinfection, where the transmission rate changed from 25% in patients with negative results for HDV Ab to 5% in those with positive results. In Hbe Ag negative male index cases, the transmission rate was 1.3% in cases with positive results for HDV Ab compared to 7% in those with negative findings. The overall transmission rate was statistically different between patients with positive and negative results for HDV Ab (P = 0.016).

CONCLUSIONS

There is a minor but consistent pattern change in the presence of HDV infection which reduces familial transmission of HBV, especially in female patients with negative results for HBe Ag.

Tears from children with chronic hepatitis B virus (HBV) infection are infectious vehicles of HBV transmission: experimental transmission of HBV by tears, using mice with chimeric human livers

BACKGROUND

Body fluids such as saliva, urine, sweat, and tears from hepatitis B virus (HBV) carriers are potential sources of HBV transmission.

METHODS

Thirty-nine children and 8 adults who were chronically infected with HBV were enrolled. Real-time polymerase chain reaction was used for the quantification of HBV DNA.

RESULTS

HBV DNA was detected in 73.7% of urine samples (14 of 19), 86.8% of saliva samples (33 of 38), 100% of tear samples (11 of 11), and 100% of sweat samples (9 of 9). Mean HBV DNA levels (±SD) in urine, saliva, tears, and sweat were 4.3 ± 1.1 log copies/mL, 5.9 ± 1.2 log copies/mL, 6.2 ± 0.7 log copies/mL, and 5.2 ± 0.6 log copies/mL, respectively. A statistically significant correlation was observed between the HBV DNA level in serum specimens and HBV DNA levels in saliva and tear specimens (r = 0.88; P < .001). Tear specimens from a child were injected intravenously into 2 human hepatocyte-transplanted chimeric mice. One week after inoculation, both chimeric mice had serum positive for HBV DNA.

CONCLUSIONS

The levels of HBV DNA in tear specimens from young children were high. Tears were confirmed to be infectious, using chimeric mice. Strict precautions should be taken against direct contact with body fluids from HBV carriers with high-level viremia.