Kenichi Komada1, Masaya Sugiyama2, Phengta Vongphrachanh3, Anonh Xeuatvongsa4, Bouaphan Khamphaphongphane3, Tomomi Kitamura1, Tomoko Kiyohara5, Takaji Wakita5, Hitoshi Oshitani6, Masahiko Hachiya7. 1. Bureau of International Health Cooperation, National Centre for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. 2. Department of Hepatic Diseases, Research Centre for Hepatitis and Immunology, National Centre for Global Health and Medicine, Ichikawa, Chiba, Japan. 3. National Centre for Laboratory and Epidemiology, Vientiane Capital, Lao PDR. 4. National Immunization Program, Vientiane Capital, Lao PDR. 5. Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan. 6. Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan. 7. Bureau of International Health Cooperation, National Centre for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: m-hachiya@it.ncgm.go.jp.
Abstract
BACKGROUND: There is limited information regarding the prevalence of hepatitis B in Lao PDR, where the hepatitis disease burden is substantial. Thus, reliable seroprevalence data is needed for the disease, based on probability sampling. METHODS: A stratified, multistage, cluster sampling survey of hepatitis B surface antigen (HBsAg) positivity among children aged 5-9 years and their mothers aged 15-45 years was conducted. Participants were selected randomly from the central region of Lao PDR via probability-proportional-to-size sampling. Blood samples were collected onto filter paper and subsequently analyzed using a chemiluminescent microparticle immunoassay. RESULTS: A total of 911 mother-and-child pairs were collected; the seroprevalence of HBsAg was estimated to be 2.1% (95% confidence interval 0.8-3.4%) among children and 4.1% (95% confidence interval 2.6-5.5%) in their mothers after taking into account the sampling design and the weight of each sample. The children's HBsAg positivity was positively associated with maternal infection and being born in a non-health facility, while the maternal infection status was not associated with any background characteristic. CONCLUSIONS: Lao PDR has a relatively lower HBsAg prevalence in the general population compared to surrounding countries. To ensure comparability to other countries and to future data, rapid field tests are recommended for a nationwide prevalence survey.
BACKGROUND: There is limited information regarding the prevalence of hepatitis B in Lao PDR, where the hepatitis disease burden is substantial. Thus, reliable seroprevalence data is needed for the disease, based on probability sampling. METHODS: A stratified, multistage, cluster sampling survey of hepatitis B surface antigen (HBsAg) positivity among children aged 5-9 years and their mothers aged 15-45 years was conducted. Participants were selected randomly from the central region of Lao PDR via probability-proportional-to-size sampling. Blood samples were collected onto filter paper and subsequently analyzed using a chemiluminescent microparticle immunoassay. RESULTS: A total of 911 mother-and-child pairs were collected; the seroprevalence of HBsAg was estimated to be 2.1% (95% confidence interval 0.8-3.4%) among children and 4.1% (95% confidence interval 2.6-5.5%) in their mothers after taking into account the sampling design and the weight of each sample. The children's HBsAg positivity was positively associated with maternal infection and being born in a non-health facility, while the maternal infection status was not associated with any background characteristic. CONCLUSIONS:Lao PDR has a relatively lower HBsAg prevalence in the general population compared to surrounding countries. To ensure comparability to other countries and to future data, rapid field tests are recommended for a nationwide prevalence survey.