Archives of the Balkan Medical Union vol. 55, no. 1, pp. 98-107 Copyright © 2020 Balkan Medical Union March 2020 ORIGINAL PAPER INCIDENCE OF ECHINOCOCCOSIS IN THE PLEVEN REGION OF BULGARIA IN THE PERIOD 1998-2017 Martin P. LALEV1, Joana I. SIMEONOVA2, Ludmil S. STOYANOV4 , Zheni S. BOSHNAKOVA3, Ivelin A. ANGELOV4 1 Laboratory of Parasitology, University Hospital – Pleven, Bulgaria 2 Department of Pharmaceutical Sciences and Social Pharmacy, Faculty of Pharmacy, Medical University – Pleven, Bulgaria 3 Department of Infectious Diseases Control, Regional Health Inspectorate – Pleven, Bulgaria 4 Department of Infectious Diseases, Epidemiology, Parasitology and Tropical Medicine, Medical University – Pleven, Bulgaria Received 03 Jan 2020, Corrections received 19 Jan 2020, Accepted 11 Febr 2020 https://doi.org/10.31688/ABMU.2020.55.1.11 ABSTRACT RÉSUMÉ Introduction. Cystic echinococcosis (CE) is a zoonot- Étude de l’incidence de l’échinococcose dans la ré- ic parasitosis still encountered in Balkan countries. gion de Pleven pour la période 1998-2017 Bulgaria is a country with a high incidence of CE and ranks first among the countries of European Union. Introduction. L’échinococcose kystique (EC) est une Objectives. The study aimed at analyzing the trends parasitose zoonotique de grande importance médicale in CE incidence from 1998 to 2017 in the Pleven re- et sociale pour l’homme. La Bulgarie est un pays avec gion of Bulgaria and of finding out if the implemen- une incidence élevée d’EC et est classée au premier tation of the Bulgarian national program for control rang des pays de l’Union européenne par le nombre of cystic echinococcosis in humans and animals has de cas enregistrés chaque année. resulted in the decrease of the disease rates. Objectifs. L’objectif de l’étude est d’analyser l’inci- Methods. This study of echinococcosis in the Pleven dence de l’échinococcose dans la région de Pleven au region covers 20 years (1998–2017) and is divided into cours de la période 1998-2017 et d’évaluer si la mise two parts: before and after the introduction of the en œuvre du programme national du contrôle de EC 5-year program for control. Data were collected from chez l’homme et l’animal a entraîné une diminution epidemiological records and histories of 248 subjects du taux d’incidence. with primary CE. Méthodes. L’étude couvre une période de 20 ans Results. A high incidence was registered during the (1998-2017), divisée en deux parties : avant et après o first studied period (1998 – 2007) – 5.27 /oooo, which l’introduction d’un programme de 5 ans pour le o in 1999 reached 8.14 /oooo. After implementation of contrôle de l’échinococcose chez l’homme. Les don- the national program, the yearly incidence of hydatid nées des dossiers médicaux de 248 personnes atteintes disease showed a statistically significant decrease, de TDM primaire ont été utilisées. Address for correspondence: Ludmil S. STOYANOV Address: Saint Kliment Ohridski Street no.1, 5800 Pleven, Bulgaria Email: [email protected]; Phone: +359 889907713 Archives of the Balkan Medical Union o reaching 2.42 /oooo in 2017. The analysis of the data Résultats. Au cours de la première période de l’étude showed that the incidence was higher among work- (1998-2007), une incidence moyenne élevée d’échino- o ing-age people and in the 5-19 years old age group. coccose a été enregistrée – 5,27 /oooo, qui en 1999 a o Conclusions. The persistence of a relatively high in- atteint 8,14 /oooo. Après l’introduction du programme cidence in the young age group is a sign of continuing national, l’incidence annuelle moyenne de l’EC a active transmission of the infection and demonstrates montré une tendance à la baisse statistiquement signi- o the necessity to continue active measures. ficative et a atteint 2,42 /oooo en 2017. L’analyse des données montre que l’incidence est plus élevée dans Keywords: cystic echinococcosis, Echinococcus gran- le groupe d’âge de 5 à 19 ans et chez les personnes en ulosus, incidence. âge de travailler. Conclusions. Le maintien d’une incidence relative- Abbreviations: CE = Cystic Echinococcosis; PAIR = ment élevée dans le groupe d’âge jeune est un signe de puncture-aspiration-injection-reaspiration. transmission réelle continue de l’invasion et indique la nécessité d’interventions actives continues à la source. Mots-clés: échinococcose kystique, Echinococcus granulosus, incidence. INTRODUCTION MATERIALS AND METHODS Cystic echinococcosis (CE) is a zoonotic para- The study on the incidence of CE in the Pleven sitosis still encountered in Balkan countries. The region covers twenty years (1998–2017). We used data etiological agent is Echinococcus granulosus, a small from medical records of 248 subjects with primary tapeworm that dwells in the intestinal tract of dogs, CE. All patients were diagnosed intraoperatively, and jackals, wolves, and other carnivorous animals. The the diagnoses were confirmed by histological and cy- larval form of the parasite, hydatid cyst, is the form tological tests in those who underwent PAIR therapy. of the parasite that is found in humans1. We collected data regarding age, sex, place of Human CE is a severe, chronic disease, with residence, and the year of surgery. The category vari- relapses that may lead to complications and death. ables were described as a number and percentage of Bulgaria is a country with a high incidence of CE and patients in each category of a variable. Age is a quan- ranks first among the European Union (EU) coun- titative variable that was described by the median tries in number of cases registered per year2, 3. (Mdn) and the range (minimal and maximal value of Over the last decades, there has been a nega- the variable in the order statistics). tive trend related to CE. More and more often, the For statistical analysis, we divided the patients disease is diagnosed in young patients, and this ac- into age groups. When defining the level of age-ad- counts for almost one-fourth of all patients operated justed incidence rates, the following groups were for CE4, 5. The number of cases of primary multi-or- formed: 0-14 years, 15-59 years, and 60+years (the gan and complicated CE has also increased6. The Bulgarian population). Then, the second and the high disease rate of CE, that in 2001 was as high as third age groups were changed to 15-64 years and 65+ o 9.21 /oooo, necessitated the implementation in 2004 of years (standard European population). Data of the a nationwide program for the control of CE in ani- Pleven region population were used by the Regional mals and humans7. Despite the drop in incidence af- Health Inspectorate – Pleven8. Also, we used data o ter the program started (3.95 /oooo in 2010), over the of the Bulgarian population by the National Center following years, the incidence increased again and has of Public Health and Analyses9 and the National stayed high6. Statistical Institute10. Data about the European pop- ulation were used by European Health for all data- THE OBJECTIVE OF THE STUDY was to analyze the bases11. When we calculated the incidence rates of trends in CE incidence from 1998 to 2017 in the CE by age group, we divided the patients into eight Pleven region, and find out if the implementation of groups, as follows: (1-9 years, 10-19 years, 20-29 years, the national program for control of the disease has 30-39 years, 40-49 years, 50-59 years, 60-69 years, and resulted in the decrease of the disease rates. 70+ years)12. The data were statistically processed with soft- ware package SPPS v.24.0. March 2020 / 99 Incidence of echinococcosis in the Pleven region of Bulgaria in the period 1998-2017 – LALEV et al Table 1. Distribution of CE patients in Pleven region by demographic characteristics. Variable N (%) Variable N (%) Age Sex Average age (yrs) Mdn=43.0 (4÷88) Males 107 (43.1) 0-14 26 (10.5) Females 141 (56.9) 15-59 156 (62.9) Total 248 (100.0) 60+ 66 (26.6) Total 248 (100.0) Residence (municipality) Pleven 90 (36.3) Cherven bryag 36 (14.5) D. Dabnik 20 (8.1) Residence Levski 12 (4.8) Regional town 51 (20.6) Nikopol 10 (4.0) Small town (municipality) 70 (28.2) D. Mitropolia 17 (6.9) Village 127 (51.2) Iskar 16 (6.5) Total 248 (100.0) Belene 4 (1.6) Pordim 5 (2.0) Gulyantsi 12 (4.8) Knezha 26 (10.5) Total 248 (100.0) Table 2. Number of new cases and incidence rates of cystic echinococcosis o ( /oooo) in the Pleven region for the two periods compared. Number of Incidence rates Number of Incidence rates Year o Year o cases ( /oooo) cases ( /oooo) 1998 12 3.72 2008 13 4.42 1999 26 8.14 2009 12 4.13 2000 24 7.62 2010 4 1.50 2001 28 8.60 2011 11 4.12 2002 11 3.43 2012 12 4.56 2003 14 4.43 2013 5 1.93 2004 10 3.22 2014 8 3.04 2005 19 6.32 2015 6 2.38 2006 8 2.65 2016 6 2.38 2007 13 4.36 2017 6 2.42 Total 165 5.27* Total 83 3.13* *Mean annual incidence of CE for 1998-2007 The absolute change is calculated from the ab- RESULTS solute level (yi) of a single period considered as a base of reference (with fixed base, 1998) or from one pe- The study included 248 patients with CE (Table riod to another (with the base chained) in formulae 1). The percentage of women affected was higher than that of men (56.9% and 43.1%, respectively).