title: Seroprevalence of chronic hepatitis B, as determined from dried blood spots, among children and their mothers in central Lao People's Democratic Republic: a multistage, stratified cluster sampling survey.
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.
authors.affiliation: Bureau of International Health Cooperation, National Centre for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, Tokyo 162-8655, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Komada
authors.affiliation: Department of Hepatic Diseases, Research Centre for Hepatitis and Immunology, National Centre for Global Health and Medicine, Ichikawa, Chiba, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Sugiyama
authors.affiliation: National Centre for Laboratory and Epidemiology, Vientiane Capital, Lao PDR.
authors.forename: Phengta
authors.initials: P
authors.lastname: Vongphrachanh
authors.affiliation: National Immunization Program, Vientiane Capital, Lao PDR.
authors.forename: Anonh
authors.initials: A
authors.lastname: Xeuatvongsa
authors.affiliation: National Centre for Laboratory and Epidemiology, Vientiane Capital, Lao PDR.
authors.forename: Bouaphan
authors.initials: B
authors.lastname: Khamphaphongphane
authors.affiliation: Bureau of International Health Cooperation, National Centre for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, Tokyo 162-8655, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kitamura
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kiyohara
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Takaji
authors.initials: T
authors.lastname: Wakita
authors.affiliation: Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Oshitani
authors.affiliation: 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.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hachiya
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D059788:Dried Blood Spot Testing; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood; D019694:Hepatitis B, Chronic / Q000453:epidemiology*; D006801:Humans; D007812:Laos / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009035:Mothers; D015995:Prevalence; D012494:Sampling Studies; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D006514:Hepatitis B Surface Antigens
keywords: Chemiluminescent microparticle immunoassay; Dried blood spots; Hepatitis B; Probability sampling; Seroprevalence; Southeast Asia