A nationwide community-based survey on hepatitis C virus (HCV) was carried out in seven townships in Taiwan. A total of 11,904 men aged 30-64 years were recruited for testing for antibodies against HCV (anti-HCV) by second-generation enzyme immunoassay. A total of 272 seropositive cases and 282 seronegative controls were interviewed to explore risk factors for HCV infection in the study areas. Spouses of 214 seropositive cases were identified to assess the concordance of seropositivity of anti-HCV between spouses; genotypes of HCV were also tested in 26 couples who were both seropositive. A significant geographic variation in seroprevalence of anti-HCV was observed in the study townships (1.6-19.6%). Blood transfusions, medical injections, acupuncture and tattooing were related to an increased anti-HCV seroprevalence showing multivariate-adjusted odds ratios of 8.6, 2.5, 3.1, and 2.2, respectively, with corresponding population attributable risk percentages of 25%, 57%, 16%, and 3%, respectively. The anti-HCV prevalence in spouses of index cases (24%) was significantly higher than that observed in the general population of the study areas (4%). However, a striking interspousal discrepancy in HCV genotypes (20/26 = 77%) was observed among both seropositive couples. Common exposures to medical injections and acupuncture were reported by 15 (58%) of these couples. This study identified some endemic areas of HCV infection in Taiwan. Iatrogenic factors were common vehicles for HCV infection, and a concordance of anti-HCV seropositivity between spouses may primarily be due to extrafamilial iatrogenic infectious sources in study areas.

A hepatitis B mass immunization program was launched in Taiwan in July 1984, beginning with newborns of hepatitis B carrier mothers for the first 2 years of the program, which was then extended to all newborns. Seroepidemiology was studied in 3 cohorts at age 6 years. Each cohort consisted of 1500 children proportionally and randomly sampled from those entering elementary school in 1989, 1991, and 1993, representing those born 1 year before the program began and years 1 and 3 of the program, respectively. By RIA, the hepatitis B surface antigen positivity rates in the groups were 10.5%, 6.3%, and 1.7%, respectively; hepatitis B surface antibody positivity rates were 36.9%, 62.0%, 65.4%; and hepatitis B infection rates were 25.0%, 15.9%, 4.3%. Thus, universal immunization was more effective in reducing hepatitis B carriage than selective immunization of newborns of carrier mothers only. The program has proved effective in controlling chronic hepatitis B infection in Taiwan.

In Taiwan, we found two hepatitis B virus (HBV)- and hepatitis C virus (HCV)-endemic townships, Paisha and Tzukuan, with an anti-HCV prevalence of 19 and 37% in men, and 26 and 38% in women, respectively. The hepatitis B surface antigen (HBsAg)-positive rates were 25 and 18%, for men and women in Paisha, and 25 and 22% in Tzukuan, respectively. According to the national death certification database (1982 to 1991), the annual age-adjusted mortality rates per 100,000 population for liver cancer among men and women were 83.0 and 13.8, respectively, in Paisha, and 55.9 and 17.0 in Tzukuan compared with 30.9 and 9.1 in Taiwan as a whole. The male-to-female ratios were 6.0 in Paisha and 3.3 in Tzukuan. Aetiology of 11 cases of hepatocellular carcinoma (HCC) from Paisha and 14 cases from Tzukuan were analysed. All HCC cases from Paisha were HBsAg positive, while 13/14 HCC cases from Tzukuan were anti-HCV positive. The endemic duration of HCV in Tzukuan seemed long enough to induce HCC, but the HCV appeared to be a newly introduced infection in Paisha.

Only 36% (4 of 11) of anti-HCV-positive children had an OD of > 2.0. Subjects with sequentially low OD might recover from chronic HCV infection without detectable HCV RNA and with normal alanine aminotransferase values.