Horizontal transmission of HBV infection among students in Turkey.

In this study, the HBsAg carrier state and the role of horizontal transmission were investigated among primary and high school students in southeastern Anatolia where HBsAg seropositivity is remarkably high. In total, 350 students from primary school first grade, 350 students from fifth grade, 400 students from high school eleventh grade and 400 healthy adults as a control group were studied. In all cases HBsAg and anti-HBs were screened by ELISA. HBsAg positivity was 2.4% in first grade, 6.1% in fifth and 6.7% in eleventh grade students. Anti-HBs positivity was 14% in first grade, 20% in fifth and 21% in eleventh grade students. HBsAg positivity was 9% and anti-HBs, 49% in the control group. There is a significant difference between first and fifth grade students for HBsAg positivity (2.1% vs 6.1% and P<0.05). This difference decreased during the high school years (6.2% and P>0.05). There is also a similar statistically significant difference for anti-HBs positivity during the primary school years (14% vs 20%, P<0.05). These findings show that the risk of horizontal transmission of HBV is especially important during elementary school years between the ages of 7 and 11 y. All infants or at least elementary school first grade students in Turkey should have HBV vaccinations.