DOI: 10.1515/folmed-2017-0005 ORIGINAL ARTICLE, MEDICINE Epidemiological Study of Hepatitis A Infection in Eastern Bulgaria Gabriela St. Tsankova1, Tatina T. Todorova1, Neli M. Ermenlieva2, Tsvetelina K. Popova2, Dayana T. Tsankova3 1 Department of Preclinical and Clinical Sciences, Faculty of Pharmacy, Medical University of Varna, Varna, Bulgaria 2 Medical College, Medical University of Varna, Varna, Bulgaria 3 Faculty of Dental Medicine, Medical University of Varna, Varna, Bulgaria Correspondence: Background: Hepatitis A virus (HAV) infection is an acute, self-limited liver disease Gabriela St. Tsankova, Department transmitted usually through the faecal-oral route via person-to-person contact. of Preclinical and Clinical Sciences, Bulgaria has intermediate HAV endemicity with higher susceptibility among adults Faculty of Pharmacy, Medical Univ- and recurrent outbreaks. ersity of Varna, 3 Bregalnica St., 9000 Varna, Bulgaria Aim: As HAV infection is strongly related to human movements and represents a E-mail: [email protected] signifi cant risk to travelers and migrants, as well as to local population receiving Tel: +359 888 006 401 these groups, we set out to analyze the epidemiological data on hepatitis A in fi ve Received: 29 Apr 2016 of the largest tourist border regions of Bulgaria located in its eastern part: Varna, Accepted: 09 Aug 2016 Shumen, Dobrich, Burgas and Yambol. Published Online: 29 Nov 2016 Materials and methods: We reviewed retrospectively all reported cases of acute Published: 27 March 2017 hepatitis A in the eastern regions of Bulgaria over a 7-year period between 2008 and 2014. Key words: hepatovirus, infec- tious hepatitis, liver infl ammation, Results: A total of 2879 newly infected patients were registered during the study epidemiology period, the number varying widely: from 190 cases in 2014 to 923 in 2012. The av- erage incidence of HAV was higher in the south-eastern regions than in the north- Citation: Tsankova GS, Todorova eastern regions (55.30%000 vs 15.04%000 respectively, p < 0.0001). The most af- TT, Ermenlieva NM, Popova TK, fected age group in all regions was the 5-9-year olds (p < 0.0001) and males were Tsankova DT. Epidemiological study of hepatitis A infection in signifi cantly more susceptible to HAV (p = 0.02). Eastern Bulgaria. Conclusion: Hepatitis A is still a major public health problem in Bulgaria; there is Folia Medica 2017;59(1):63-69. a signifi cant diff erence in the incidence of the disease between the regions in the doi: 10.1515/folmed-2017-0005 south-east and those in the north-east and between the diff erent age groups and sexes. BACKGROUND rus is released into bile and, eventually, shed in Hepatitis A virus (HAV) infection is an acute, the feces.4 The infection is asymptomatic among self-limited disease of the liver with world-wide children up to 6 years whereas in more than 70% distribution.1 Generally, it is transmitted through of the cases among adolescents and adults it leads the faecal-oral route via person to person contact. to clinical disease.1 Alimentary and water routes are also possible. In According to World Health Organization, clinical rare cases HAV can be transmitted via infected cases with HAV account for 1.5 million each year blood of asymptomatic donors and people in in- with the highest number registered in Africa, Asia, cubation period.2 Despite the clinical form of the Central and South America.5 The spread of hepatitis disease (asymptomatic, subclinical, symptomatic or A strongly correlates with low socioeconomic and fulminant), the sick person with acute infection is cultural development of a country.3 The majority the reservoir for spreading of the infection. In the of cases occur in developing countries with unsafe late incubation period (1-2 weeks before the onset water and poor sanitation infrastructure.6 Serological of prodromal symptoms) and during the fi rst week prevalence profi les vary widely among countries.2,6 after the onset of jaundice, the virus is released In highly endemic areas (e.g. Sub-Saharan Africa with the feces in concentrations higher than 108 and parts of South-East Asia) at least 90% of the particles in 1 ml.3 Following the ingestion by the population becomes immune by the age of 10. In new host, HAV particles reach the liver and infect communities with intermediate endemicity (Southern hepatocytes. After replication in the liver, the vi- and Eastern Europe, China, Latin America, Northern 63 Folia Medica I 2017 I Vol. 59 I No. 1 G. Tsankova et al Africa, the Middle East and Russia) at least 50% A in the chosen regions were investigated over a of the population is immune by the age of 15. 7 year-period (2008-2014). Higher susceptibility among adults and recurrent The incidence rates for each region were calcu- outbreaks are observed in these areas. In regions lated on the basis of offi cially reported confi rmed with low endemicity (prevalence of anti-HAV an- cases of HAV divided by the population estimates tibody exceeds 50% by age of 30 but is less than of each region for the corresponding year (http:// 50% by age of 15) and very low endemicity (less www.nsi.bg/). Sociodemographic data were also than 50% seroprevalence by age 30 years) such as obtained by the offi cial statistics of the National Western and Northern Europe, Australia, Canada, Statistical Institute and estimates from the last Japan, and the United States disease may occur census (2011) were used for correlation analysis. among specifi c-risk groups.1,2 Statistical analyses were performed with EpiInfo7 Despite the improved sanitary hygienic conditions, software (contingency table analysis, chi-square) the morbidity of HAV in Bulgaria is still an important or “R” software (correlation coeffi cient tests); p < problem and the country is currently placed in the 0.05 was considered statistically signifi cant. list of intermediate endemicity areas. From 1984 to 2005, the average incidence has varied between RESULTS 27 – 80 cases per 100 000 population during non- Between 2008 and 2014, a total of 2879 newly epidemic periods and has reached 234 cases/100 infected individuals were registered in the fi ve 000 during epidemic periods.7 No recent published studied regions (Table 1). The total incidence data are available regarding the HAV incidence rates varied widely – from 190 cases in 2014 to 923 in in Bulgaria and the burden of the disease cannot 2012. Burgas showed the highest average incidence be easily defi ned. HAV infection is highly related of HAV infection in 2012 (144.63%000) with 599 to human movements and represents a signifi cant infected individuals, while the lowest was reported risk to travelers and migrants, as well as to local for Varna in 2010 (0.94%000) (Fig. 1). Statistically population receiving these groups.8 Over the last signifi cant trend of increase or decrease during the decade, Bulgaria has experienced an increase in investigated period was not observed for any of international transport and human connections and the regions. in this context it is important to know the actual Southeastern regions (Burgas and Yambol) burden of HAV and other infectious diseases. showed higher average incidence of HAV (with a total of 1943 infected persons per population of AIM 539908, according to the national 2011 census) The aim of this study was to analyze the epidemio- logical data on hepatitis A transmission in fi ve of 160 the largest regions of Bulgaria – Varna, Shumen, Dobrich, Burgas and Yambol – which represent the 140 eastern part of the country. 120 100 MATERIALS AND METHODS 80 We analyzed HAV epidemiological patterns in Dobrich, Shumen, Varna (located in the northeast) 60 and in Burgas and Yambol (in the southeast). The 40 information for the number of HAV cases was 20 received from the Regional Health Inspections in 0 Varna, Dobrich, Shumen, Burgas and Yambol. In 2008 2009 2010 2011 2012 2013 2014 Bulgaria, hepatitis A infection is a nationally notifi - able infectious disease which must be reported from Figure 1. HAV incidence between 2008 and 2014 (blue all medical specialists when detected. The European line - Burgas; purple - Yambol; green - Varna; black - Dobrich and red - Shumen). Union case defi nition and case classifi cation of prob- able and confi rmed cases (European Commission Decision 2012/506/EU on 8 August 2012) is used compared with the regions in the north – Varna, as the basis of clinical and laboratory criteria. In Dobrich and Shumen which had a total of 936 our study, all confi rmed reported cases of hepatitis registered cases per 833537 inhabitants. The aver- 64 Folia Medica I 2017 I Vol. 59 I No. 1 Epidemiological Study of Hepatitis A Infection in Eastern Bulgaria age incidence for the whole period in the southern the incidence rates in the studied regions and so- regions was 55.30%000 while the average incidence ciodemographic variables. HAV incidence did not in the north was 15.04%000 (p < 0.0001). correlate with the following factors: total number The Spearman’s rank correlation coeffi cients of the population of the corresponding region, were calculated to assess the association between population density, Roma ethnic origin, proportion Table 1. Distribution of HAV Dobrich Shumen Varna Yambol Burgas Total n Inc.* n Inc.* n Inc.* n Inc.* n Inc.* n 2008 95 46.77 49 25.06 41 8.85 78 55.45 27 6.41 290 2009 62 30.5 18 9.27 24 5.15 160 115.58 40 9.47 304 2010 17 8.5 23 11.96 9 0.94 75 55.22 71 16.85 195 2011 8 4.05 17 9.46 50 10.54 155 119.18 220 53.02 450 2012 18 9.57 3 1.67 276 58.29 27 21.00 599 144.63 923 2013 8 4.29 10 5.61 116 24.47 50 39.31 343 82.75 527 2014 63 34.11 2 1.13 27 5.70 57 45.33 41 9.89 190 Total 271 122 543 602 1341 2879 Aver.