Comparative analysis of two epidemic outbreaks of acute hepatitis A in Stara Zagora region, Bulgaria

Acute hepatitis A (AHA) is a common infection disease in Bulgaria. It is a self-limiting illness that commonly has a benign clinical course and a favourable outcome. The most affected age group are children, especially those who have not yet formed good hygienic habits. For a 6-year period (2010-2015) 16480 cases of AHA have been registered in Bulgaria. Materials and methods: For a 6-year period (2010-2015) 2042 cases of AHA have been diagnosed and treated in the Clinic of Infectious diseases of University Hospital, Stara Zagora. 1188 were men, 854 - women; 986 of all were under 18 year old. We observed two epidemic outbreaks - in 2010/11 and in 2015/16. Epidemiological, clinical, laboratorial and serological investigations proved the diagnosis. All cases were followed up through the convalescent period. Results and discussion: The mean (+/- SD) age of the patients with AHA during the first epidemic outbreak was 28.8 +/- 17.0 (range 2-63) years and 23.3 +/- 19.4 (range 2-73) years during the second one. Male were more affected than female. The most observed clinical form in both outbreaks was the moderate one. Reshuts, forced re-hospitalization were reported in 16 patients in the first, respectively in 9 in the second period. Almost all our patients were successfully recovered. The death-rate was 0.09%. Despite of profound research the sources of infection remained unknown. Conclusion: Comparative statistical analyses showed that during the first outbreak unexpectedly prevailed adults with good social status and sanitary habits. In addition moderate and severe clinical forms predominated and direct statistical significances with the age were determined. An accent on the application of specific vaccine against hepatitis A was placed.