[Seroepidemiology of hepatitis A in Saint-Petersburg in 2009].

Aim: To determine immune structure of different population groups in Saint-Petersburg to hepatitis A virus in 2009 in order to study trends of epidemic process dynamics and planning of prophylactic measures.

Materials And Methods: Nine hundred and three citizens of Saint-Petersburg aged 3 months to 60 years were tested for anti-HAV by ELISA in 2009. Results were compared with data of previous study conducted in Saint-Petersburg in 1999. Two hundred injection drug users (IDUs) aged 14 - 29 years were tested additionally.

Results: In total in 2009, anti-HAV were detected in 32.5 +/- 1.6% citizens of Saint-Petersburg that is 2-fold lower than in 1999 (60.2 +/- 1.5%). Especially sharp decrease of anti-HAV prevalence in 2009 compared to 1999 was observed in age groups 15 - 19 years (by 2.6-fold), 20 - 29 years (by 3.1-fold), and 30 - 39 years (2.8-fold). Anti-HAV were detected in 58.5 +/- 3.5% of tested IDUs that 2.8-fold higher of that value observed in persons 14 - 29 years old from population sample (21.7 +/- 2.4%).

Conclusion: Decrease of immunity to HA in population of Saint-Petersburg is very unfavorable prognostic factor pointing to strong possibility of HA outbreaks onset during worsening of epidemic situation. In such circumstances, active immunization against HA of wide strata of population should become important prophylactic measure.