| Summary: | 碩士 === 國立臺灣大學 === 公共衛生學系 === 83 ===
Hepatitis B virus (HBV) infection is highly endemic in Taiwan. Since 1986 when the HBV universal vaccine program was initiated, the HBV carrier rate has been significantly decreased. Serological tests of HBV markers have been commonly used as the index of infection, but the recent use of polymerase chain reaction (PCR) test revealed the presence of HBV DNA even in some HBsAg (-) cases. Vaccinated children have been found to be infected by some immune-escape mutants that in turn might pose a potential threat to the HBV vaccination program in the furture.
This study were carried out in three parts:1) utilizing the enzymelinked immunosorbent assay (ELISA) on the serum collected in a two-year follow-up study of aboriginal Tawiwanese school children, we aimed to understand the horizontal transmission pattern and trends of HBV infection; 2) using the PCR test, we tried to detect the presence of HBV DNA in some individuals who had been tested HBsAg (-) by ELISA ; 3) conducting a cross-sectional study on vaccinated and unvaccinated aboriginal Taiwanese school children to detect the occurrence of the “a ”determinant mutant strain virus via molecular biologic techniques. In doing so, this study will provid the first systematically surveyed mutant strains of HBV in Taiwan.
In this study we demonstrated that: 1) the frequency of horizontal transmission and infection of HBV remained high among aberiginal Taiwanese school children; observation of trend showed an cumulative infection rate with increasing age; 2) among the aboriginal Taiwanese school children included in this study (ages 7-13 ), the annual infection rate was 7.4%; children having protective antibody ( anti- HBs titer > 10 IU/L ) could still acquire new infection or be reinfected; 3) by using PCR test, one can still detect HBV DNA in HBsAg (-) cases; 4) the “a ”determinant mutants was isolated from one vaccinated school child and unvaccinated adults; 5) among the 4 major subtypers of HBV virus, the adw straim was the dominant strain.
Further suggestions: 1) to follow-up the aboriginal children in order to understand the reasons for such a high rate of horizontal transimission; 2) to monitor the occurrence, distribution, and future trends in transmission of these variants among the immunized children.
|
|---|
