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Open Access Highly Accessed Research article

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

Antony P Black12, Phonethipsavanh Nouanthong1, Naphavan Nanthavong3, Chanthasone Souvannaso1, Keooudomphone Vilivong1, Prapan Jutavijittum4, Bounthome Samountry5, Nina Lütteke12, Judith M Hübschen12, Sylvie Goossens6, Fabrice Quet3, Yves Buisson3 and Claude P Muller12*

Author Affiliations

1 Lao-Lux Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR

2 Institute of Immunology, Centre de Recherche Public de la Santé/Laboratoire National de Santé, 20A, rue Auguste Lumière, L-1950 Luxembourg, Grand-Duchy of Luxembourg

3 Institut de la Francophonie pour la Médecine Tropicale, Vientiane, Lao PDR

4 Department of Pathology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand

5 Department of Pathology, Faculty of Medicine, University of Health Sciences, Vientiane, Lao PDR

6 Independent consultant, Vientiane, Lao PDR

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BMC Infectious Diseases 2014, 14:457  doi:10.1186/1471-2334-14-457

Published: 23 August 2014

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.

Keywords:
Hepatitis B virus; Serology; Vaccine; Cross-sectional