Hepatitis B Virus Infection In China Research Articles

Epidemiology and prevention of hepatitis B virus infection in China

The concept of a hepatitis B vaccine was first introduced into China in 1978. China has been one of the first two developing countries to enact the universal hepatitis B vaccination programme for newborn babies in 1992, and has made tremendous achievements in the control of hepatitis B virus (HBV) infection since then. China now has both low and high endemic regions regarding HBV prevalence co-existing. Although China's drive to stop HBV spread has resulted in changes in HBV epidemic patterns, for the eventual elimination HBV infection in China, it is important to understand the current status of its epidemiology and the aspects of HBV transmission in different regions. More efforts are needed to improve and develop strategies for the control of HBV infection in China, particularly after implementing the policy of universal HBV immunization for all newborns.

Modeling the transmission dynamics and control of hepatitis B virus in China

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV) and is a major global health problem. HBV is the most common serious viral infection and a leading cause of death in mainland China. Around 130 million people in China are carriers of HBV, almost a third of the people infected with HBV worldwide and about 10% of the general population in the country; among them 30 million are chronically infected. Every year, 300,000 people die from HBV-related diseases in China, accounting for 40-50% of HBV-related deaths worldwide. Despite an effective vaccination program for newborn babies since the 1990s, which has reduced chronic HBV infection in children, the incidence of hepatitis B is still increasing in China. We propose a mathematical model to understand the transmission dynamics and prevalence of HBV infection in China. Based on the data reported by the Ministry of Health of China, the model provides an approximate estimate of the basic reproduction number R(0)=2.406. This indicates that hepatitis B is endemic in China and is approaching its equilibrium with the current immunization program and control measures. Although China made a great progress in increasing coverage among infants with hepatitis B vaccine, it has a long and hard battle to fight in order to significantly reduce the incidence and eventually eradicate the virus.

Hepatitis B virus genotypes and subgenotypes in China

Eight Hepatitis B virus (HBV) genotypes (A to H) have been identified based on an intergenotype divergence of 8% or more in the entire nucleotide sequence. Subgenotypes have also been identified in different HBV genotypes. As a highly endemic area for HBV infection, the prevalence of chronic HBV infection in China is between 8 and 20% of the general population. Genotypes B and C were identified as the most common HBV strains and account for approximately 95% of Chinese patients. Further study confirmed all genotype B strains belong to subgenotype Ba. Two of genotype C subgenotypes, C1 (Cs) and C2 (Ce), were found in China and they showed different geographic distributions. Genotype A was very rarely found, while genotypes E, F, G and H have not beenreported until now. Two types of HBV C/Drecombinant viruses have been identified in west China and distinct geographic and ethnic distributions were observed. Significant differences were observed (P < 0.001) in the prevalence of A1896 and T1762/A1764 mutations among HBV Ba, C1 and C2 subgenotypes in Chinese patients. Accumulating evidence showed the response rate to antiviral therapy in Chinese patients is higher in genotype B than genotype C patients on interferon treatment, but no difference was observed on nucleoside/nucleotide analog treatment.

A mathematical model of hepatitis B virus transmission and its application for vaccination strategy in china.

Before universal infant immunization against hepatitis B virus (HBV) in 1986 China was a region endemic for HBV infection. The prevalence of HBV infection in the population was about 60% and the proportion of chronic HBV carriers around 10%. These HBV carriers could progress to chronic hepatitis B, cirrhosis, and primary hepatocellular carcinoma. Since 1976, large-scale sero-surveys of HBV infection have been carried out and a lot of data have been collected. This paper describes a mathematical model developed to predict the dynamics of HBV transmission and to evaluate the long-term effectiveness of the vaccination programme. We used a compartment model expressed by a set of partial differential equations based on the characteristics of HBV infection. All parameters, expressed in the model as a non-linear function of age and time since vaccination, were estimated using sero-survey data. The model fits well with both pre-vaccination and post-vaccination sero-surveys. The observed and estimated age-specific prevalence rates of HBV infection and HBV carriage agree with each other. According to our model, if all newborns are vaccinated according to schedule, the rate of HBV carriage will decline sharply over time to 0.2% in 70 years. By then, the ratio of acute hepatitis B will be less than 0.5% and the ratio of chronic hepatitis B will be around 5%. The results suggest that HBV infection in China can be controlled in just one generation, and eventually eliminated. Our model shows that vaccination coverage is the most important indicator for the elimination of HBV transmission. The higher the vaccination coverage, the better the long-term effectiveness of immunization. Thus, the key to controlling and eliminating HBV transmission in China is to find ways to immunize all infants throughout the country, especially in poor, rural areas.