The changing patterns of acute hepatitis B infection in Korea in the early 2000's

Background : The prevalence of the hepatitis B virus (HBV) carrier state in Korean children is markedly reduced after the introduction of routine HBV vaccination program. The aims of this study were to evaluate the recent changing patterns of acute HBV infection, and to elucidate the diagnostic value of IgM anti-HBc in distinguishing acute hepatitis B from acute exacerbation in chronic HBV infection (CHB). Methods : Fifty seven patients with acute hepatitis B and ninety nine patients with acute exacerbation in CHB were included. The titer of IgM anti-HBc was measured and the distribution of age was analyzed retrospectively. Signal to cut off ratio (S/CO ratio) of IgM anti-HBc was calculated in each IgM anti-HBc positive cases. Results : The peak age of acute hepatitis B was 30-39 years old in 2000's. IgM anti-HBc was positive in 25.3% of CHB with acute exacerbation and the peak age of this group was also 30-39 years old. Mean(SD) value of S/CO ratio was 8.39.1 in CHB group, while 22.918.7 in acute hepatitis group. The difference was significant between two groups (p value=0.001). However, S/CO ratio in 43.6% of CHB group was greater than 3. Conclusions : The incidence of acute hepatitis in Korea was highest in 30-39 years old recently. Therefore, catch-up vaccination is better to be recommended in adults. As the peak age of distribution of acute hepatitis B and CHB with acute exacerbation overlaps, much more caution is needed to differentiate these two conditions from each other by IgM anti-HBc only.