Hepatitis delta virus infection in southern Taiwan

Highly endemic hepatitis B infection in rural Vietnam

BACKGROUND AND AIM

Hepatitis B is a major public health problem in Vietnam; however, estimates of the prevalence of hepatitis B virus (HBV) and hepatitis delta virus (HDV), and risk factors in rural Vietnam are limited. The aim of this study was to determine HBV and HDV prevalence, and identify risk factors for HBV infection.

METHODS

A cross-sectional seroprevalence study was undertaken in two rural districts in Thai Binh province. The study population was randomly selected using multistage sampling. Demographic and behavioral risk information and serological samples were obtained from 837 participants.

RESULTS

Mean age was 42.3 years +/- 15.8 (range, 16-82 years), and 50.8% were female. Prevalence of anti-HBV core antibody (anti-HBc) and hepatitis B virus surface antigen (HBsAg) was 68.2% and 19.0%, respectively, and hepatitis B e antigen HBeAg was detected in 16.4% of the HBsAg-positive group. Prevalence of HDV was 1.3% in the HBsAg-positive group. Factors associated with HBV infection (anti-HBc or HBsAg positive) were age 60 years or older (OR, 3.82; 95% CI, 1.35-10.80; P = 0.01), residence in Vu Thu district (OR, 3.00; 95% CI, 2.16-4.17; P < 0.0001), hospital admission (OR, 2.34; 95% CI, 1.33-4.13; P = 0.003) and history of acupuncture (OR, 2.01; 95% CI, 1.29-3.13; P = 0.002). Household contact with a person with liver disease (OR, 2.13; 95% CI, 1.29-3.52; P = 0.003), reuse of syringes (OR, 1.81; 95% CI, 1.25-2.62; P = 0.002) and sharing of razors (OR, 1.69; 95% CI, 1.03-2.79; P = 0.04) were independent predictors of HBsAg positivity. Alanine aminotransferase (ALT) level was elevated (>40 IU/L) in 43% of the HBsAg-positive group; proportion elevated was higher in HBeAg-positive (65%) compared with HBeAg-negative (39%) individuals in this group (P = 0.02).

CONCLUSION

Hepatitis B virus infection is highly endemic in rural Vietnam. Poor infection control activities in health-care settings contribute to high HBV prevalence in this region. Universal HBV infant vaccination and improved infection control procedures are required for improved HBV control in Vietnam.

Rising incidence of hepatocellular carcinoma: the role of hepatitis B and C; the impact on transplantation and outcomes

Hepatocellular carcinoma caused by hepatitis B and hepatitis C are global scourges but are likely to peak in incidence in the next 2 decades and then decline. Universal vaccination has been effective in stemming the incidence of chronic hepatitis B and early-onset HCC in regions of high endemicity where implemented, but preventive measures in HCV are not yet available. After the attrition of older affected generations, the incidence of HCC will likely decline rapidly. While no vaccine is currently available for hepatitis C, cases are projected to peak and decline because of a marked reduction in transmission as a result of behavioral modification and safeguarding of blood supplies. Until these epidemiologic projections come to pass, management of hepatocellular carcinoma will continue to become a progressively more frequently encountered clinical challenge. Therapy for chronic hepatitis may ameliorate but will not eliminate the development of tumors. The demand for orthotopic liver transplantation will continue to climb, and palliative therapies for non-resectable cases will require studies aimed at optimization of benefit. LDLT may remain an option for high-risk patients affording tumor-free survival for some otherwise terminal patients.

Characterization of a new genotype II hepatitis delta virus from Taiwan

Three genotypes of HDV, which may be associated with different clinical pictures and epidemiological patterns, have been identified. In contrast to Type I and Type III HDV, both of which have multiple isolates, Type II HDV so far includes only a single isolate (Japan-1) from a low prevalence area (Japan). Recently, Type II has been reported to be the predominant genotype in Taiwan, which is also a low prevalence area, and is associated with less aggresive disease than Type I. However, the sequence and structure of these viruses have not been characterized. The complete characterization of a second member (Taiwan-3 isolate) of the Type II HDV from Taiwan is reported. These two Type II HDV isolates (Taiwan-3 and Japan-1) have 93.8% nucleotide homology and 89.3% amino acid homology, respectively. These shared sequences establish the common characteristics of Type II viruses. Sequence comparisons of various HDV genotypes show that the autocatalytic region of the RNA is relatively conserved between Type I and Type II (88.5-95.6% homology) but is significantly divergent in Type III (76.8-80.3% homology). The hypervariable region (nucleotides 1602-658) of RNA, however, is heterogeneous (64.9-73.0%) among all three genotypes. The delta antigen sequence is also very heterogeneous (64.9-73.0%). Most strikingly, the C-terminal sequence (19 amino acids) of the large delta antigen is almost completely different in each of the three genotypes. The heterogeneity in this region of three HDV genotypes may be a basis for their different biological properties, and the nucleotide sequences of this region can be used to differentiate the different genotypes of HDV. The consensus sequence in the four previously identified conserved domains of HDV RNA is defined more precisely.

Delta hepatitis: molecular biology and clinical and epidemiological features

Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection.

Hepatitis D virus superinfection remains a rare occurrence in non-drug abusers in Hong Kong

Recent studies from Taiwan reported an increased prevalence of hepatitis D virus (HDV) superinfection as well as a spread of HDV infection to non-drug abusers. We examined the current prevalence of HDV superinfection in Hong Kong by testing sera from a large cohort of patients with acute and chronic hepatitis B virus (HBV) infection, collected between January 1988 and December 1990, for IgG antibody to HDV (anti-HDV). Anti-HDV was detected in 13 (93%) of 14 parenteral drug abusers who had HBV-related chronic liver disease. However, anti-HDV was detected in only one (0.15%) of 664 non-drug abusers who had chronic HBV infection and none of 31% patients with acute hepatitis B. We concluded that HDV superinfection remains a rare occurrence in non-drug abusers in Hong Kong.

Hepatitis delta virus superinfection among patients with chronic hepatitis B in southern Taiwan

To study the prevalence of hepatitis delta virus (HDV) superinfection among patients with chronic hepatitis in southern Taiwan, total and IgM anti-delta antibody (anti-HD) and delta antigen (HDAg) were determined in 85 histology-proven patients with chronic hepatitis. There were 12/85 (14.1%) cases with total anti-HD; 3 of them were also positive for IgM anti-HD. Another 9 (10.6%) cases were positive for HDAg. Thus, the prevalence of HDV superinfection was 21/85 (24.7%), which was significantly higher than previous reports in southern Taiwan. The difference was not seen if anti-HD was used as the only detector. It is concluded that, when other methods are used than previously, HDV infection is more common than previously thought and there is no difference between different parts of Taiwan.