ABSTRACT
Taiwan was a hyperendemic area for hepatitis A virus (HAV) infection before the late 1980s. The seroprevalence of HAV infection was higher than 90% with most HAV infection occurring during childhood. This study was to estimate the seroprevalence of HAV infection among preschool children in central Taiwan. A community-based survey was carried out in 54 kindergartens in 10 urban areas, 10 rural areas and 2 aboriginal areas randomly selected through stratified sampling. Serum samples of 2,549 healthy preschool children and 104 teachers in study kindergartens were screened for the HAV antibodies (anti-HAV) by means of a commercially available microparticle enzyme immunoassay (AxSYM HAVAB). Among aboriginal kindergarten children, more than 96% of them were anti-HAV seropositive due to a mass HAV vaccination program. In urban and rural areas, kindergarten children had a very low prevalence of anti-HAV (0.4%) in contrast to a high seroprevalence in their teachers (78%). There was no gender difference in seroprevalence of anti-HAV, while the anti-HAV seroprevalence was significantly higher in urban areas than in rural areas. Crowdedness of living in urban areas might facilitate the person-to-person transmission of infectious agents.
Subject(s)
Adult , Child, Preschool , Faculty , Female , Hepatitis A/epidemiology , Hepatitis A Antibodies , Hepatitis Antibodies/blood , Hepatovirus/immunology , Humans , Immunoenzyme Techniques , Logistic Models , Male , Rural Health , Seroepidemiologic Studies , Taiwan/epidemiology , Urban HealthABSTRACT
Since the licensing of the rubella virus vaccine (RA 27/3 strain) in 1979, clinical studies on the RA 27/3 strain vaccine, which gives rise to high titer antibody, have been reported. In the present study, this vaccine was used to examine the immune response in young women. Volunteers without the previous immunity to rubella virus screened by hemagglutination inhibition (HAI), latex agglutination (LA), fluorescence immunoassay (FIA) and solid-phase immunoassay (SPIA) tests were injected with Rudivax vaccine or Meruvax II vaccine. Adverse reactions occurred between 10 and 20 days after vaccination in 30% of the volunteers. After 28-35 days, vaccinees developed antibodies against rubella virus. The titer of rubella antibody reached it's peak from the 40th day through the 100th day. One year after vaccination, the geometric mean titer (GMT) of rubella virus antibody still remained over 1 : 64 (HAI) and 1 : 38.2 (FIA), and SPIA IgG RI mean was 2.80. Two years later, the antibody titers were 1 : 52 by HAI and 1 : 32.1 by FIA, and SPIA IgG RI mean was 2.75. After 5 years, the antibody titers were 1 : 48.6 (HAI) and 1 : 28.2 (FIA), and SPIA IgG RI mean was 2.74. After 10 years, the anti-rubella virus antibody titers were 1 : 38.9 (HAI) and 1 : 25.1 (FIA), and SPIA IgG RI mean was 2.42. LA antibody still remained seropositive. In conclusion, the rubella vaccine RA 27/3 is safe and efficient, and it is applicable for the control of the rubella in Taiwan.