[Prevalence of hepatitis B and risk factors as motivation for vaccination campaign among adolescents]

To study the prevalence of viral Hepatitis B infection (VHB) among eighth-year EGB (basic) students; associated risk factors; and the prevalence of Hepatitis C (HC).

A descriptive crossover study.

Eighth-year EGB students from 8 schools in Villaverde-Usera (Madrid).

A sample of 262 individuals was used to calculate the prevalence of VHB infection (prevalence defined at 1.5%, precision = 0.015, confidence at 95% and 5% loss).

Variables were age, gender, alcohol, tattoos, drugs, family history of drugs, Hepatitis, exchanging syringes, razors, syringes, sexual relations, history of transfusions or surgery. These were obtained from a questionnaire filled in by the students themselves. The definitions were: chronic HB carrier: AgHBS+ in the blood; VHB infection: anti-HBc and/or anti-HBs positives; VHC infection: presence of anti-HC. 402 children answered the questionnaire. Serology was tested in 263 before the vaccination. Average age was 13.3 +/- 0.69. There were 52.8% males and 47.2% females. Prevalence of VHB infection was 2.28% (CI = 0.93-5.14), 6 cases. Prevalence of carriers was 0.38% (CI = 0.02-2.43; one case). There were no VHC positives. No links between VHB and risk practices could be demonstrated.

1) Low prevalence of VHB infection 2) The zero prevalence of VHC infection is lower than that in healthy donors.