Hepatitis B virus in the Lao People's Democratic Republic: a cross sectional serosurvey in different cohorts

BMC Infect Dis. 2014 Aug 23;14:457. doi: 10.1186/1471-2334-14-457.

Abstract

Background: Despite hepatitis B vaccination at birth and at 6, 10 and 14 weeks of age, hepatitis B virus (HBV) infection continues to be endemic in the Lao People's Democratic Republic (PDR). We carried out a cross-sectional serological study in infants, pre-school children, school pupils and pregnant women to determine their burden of disease, risk of infection and vaccination status.

Methods: A total of 2471 participants between 9 months and 46 years old were recruited from urban (Vientiane Capital, Luang Prabang), semi-urban (Boulhikhamxai and Savannakhet) and remote rural areas (Huaphan). All sera were tested for anti-HBs and anti-HBc. Sera testing positive for anti-HBc alone were further tested for the presence of HBsAg.

Results: A low prevalence of HBsAg (0.5%) was detected among infants from Vientiane and Luang Prabang, indicating some success of the vaccination policy. However, only 65.6% had protective anti-HBs antibodies, suggesting that vaccination coverage or responses remain sub-optimal, even in these urban populations.In pre-school children from remote areas in Huaphan, 21.2% were positive for anti-HBc antibodies, and 4.6% were for HBsAg positive, showing that a significant proportion of children in these rural regions have early exposure to HBV. In pre-school children with 3 documented HBV vaccinations, only 17.0% (15/55) were serologically protected.Among school-children from semi-urban regions of Luang Prabang, Boulhikhamxai and Savannakhet provinces, those below the age of 9 who were born after HBV vaccine introduction had anti-HBc and HBsAg prevalence of 11.7% and 4.1%, respectively. The prevalence increased to 19.4% and 7.8% of 10-14 year olds and to 27% and 10.2% of 15-19 year olds.Pregnant women from Luang Prabang and Vientiane had very high anti-HBc and HBsAg prevalence (49.5% and 8.2%), indicating high exposure and risk of onward vertical transmission to the unborn infant.

Conclusions: Overall, the results demonstrate a dramatic deficiency in vaccination coverage and vaccine responses and/or documentation within the regions of Lao PDR studied, which included urbanized areas with better health care access. Timely and effective hepatitis B vaccination coverage is needed in Lao PDR.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Female
  • Hepatitis B / blood
  • Hepatitis B / epidemiology*
  • Hepatitis B / prevention & control
  • Hepatitis B Antibodies / blood*
  • Hepatitis B Core Antigens / immunology
  • Hepatitis B Surface Antigens / blood*
  • Hepatitis B Vaccines / therapeutic use
  • Hepatitis B virus
  • Humans
  • Infant
  • Infectious Disease Transmission, Vertical
  • Laos / epidemiology
  • Male
  • Middle Aged
  • Pregnancy
  • Prevalence
  • Rural Population
  • Urban Population
  • Vaccination
  • Young Adult

Substances

  • Hepatitis B Antibodies
  • Hepatitis B Core Antigens
  • Hepatitis B Surface Antigens
  • Hepatitis B Vaccines