Introduction and objective:
Hepatitis A Virus (HAV), reportedly the most common cause of acute viral hepatitis in developing countries, infects millions of people worldwide each year. The aim of the study is to investigate the seropositivity of anti-hepatitis A virus (HAV) IgG and IgM in all age groups in Erzurum, and to determine the effect of various factors such as age, gender, climatic conditions and HAV vaccination (included in 2012 in the National Immunization Schedule on seroprevalence) on the seropositivity.

Material and methods:
The serological results of 25,007 individuals referred to Erzurum Public Health Microbiology Laboratory between January 2015 – December 2018 were retrospectively reviewed to test for the presence of anti-HAV IgG and IgM. The patient ages were 0–93 years. Serum samples were analyzed by ELISA. S/CO values of ≥1.00 and >1.21 were considered positive for anti-HAV IgG and IgM, respectively; results below this value were considered negative.

Results:
Anti-HAV IgG and IgM seropositivities were 87.3% and 0.2%, respectively. Anti-HAV IgG prevalence – 88.5% and 86.4%, anti-HAV IgM positivity – 0.1% and 0.3% in men and women. Anti-HAV IgG seroprevalence – 87%, 73.2%, 58.7%, 75.2%, 86.1%, 89.8%, 96.1%, 99.1%, 99.1% and 99.3%, respectively, at 0–4, 5–9 10–14, 15–19, 20–24, 25–29, 30–39, 40–49, 50–59 and >60 age groups. Anti-HAV IgM seropositivity – 0, 0.1%, 0.7%, 0.7%, 0.3%, 0, 0.1%, 0.2%, 0.1%, and 0.2%, respectively, in the same age groups. Anti-HAV IgM positivity was the highest in November – 36(0.97%.

Conclusions:
In Erzurum, anti-HAV IgG prevalence is tremendously high, whereas prevalence of anti-HAV IgM is exceptionally low, especially in the paediatric age group. Therefore, HAV vaccine is provided free of charge in Turkey, including Erzurum, since 2012.