Vojnosanit Pregl 2016; 73(9): 817–824. VOJNOSANITETSKI PREGLED Page 817 UDC: 616-036.22::595.42(497.11) ORIGINAL ARTICLE DOI: 10.2298/VSP150115069K Prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and assessment of entomological risk index at localities in Belgrade Prevalencija Borrelia burgdorferi sensu lato kod krpelja Ixodes ricinus i procena entomološkog indeksa rizika na lokalitetima Beograda Milena Krstić*†, Novica Stajković*†, Srdjan Lazić*† *Institute of Epidemiology, Sector for Preventive Medicine, Military Medical Academy, Belgrade, Serbia; †Faculty of Medicine of the Military Medical Academy, University of Defence, Belgrade, Serbia Abstract Apstrakt Background/Aim. The first case of human Lyme borreliosis Uvod/Cilj. Prvi slučaj lajmske borelioze (Lyme borreliosis, (LB) in Serbia was recorded in 1987. The number of reported LB LB) u Srbiji zabeležen je 1987. Broj prikazanih bolesnika sa cases has increased in the past decade. The aim of this study was LB porastao je tokom poslednje dekade. Cilj ovog istraživanja to estimate the density of Ixodes ricinus (I. ricinus) ticks, the preva- bio je da se procene gustina krpelja Ixodes ricinus (I. ricinus), lence of Borrelia burgdorferi sensu lato (B. burgdorferi) in them, and en- prevalencija Borrelia burgdorferi (B. burgdorferi) u njima i tomological risk index (ERI) at 19 Belgrade localities which were entomološki indeks rizika (ERI) na 19 beogradskih lokaliteta grouped into three categories (forests, park-forests, parks). The grupisanih u tri ekološke kategorije (šume, park-šume, parko- values of ERI were compared with the number of tick bites in vi). Vrednosti ERI upoređivane su sa brojem uboda krpelja humans. Methods. Ticks were collected monthly by using the kod ljudi. Metode. Krpelji su prikupljani mesečno pomoću flag hours method and the infection rate was determined by us- metode flаg časa, a stopа infekcije određivana je u tamnom ing dark field microscopy. The ERI value was calculated for each polju mikroskopa. ERI vrednost je izrаčunаvana zа svаki locality where the ticks were collected. The related data about lokаlitet na kome su sаkupljeni krpelji. Podаci o ubodima tick bites was obtained from the patient protocol of the Institute krpelja stаnovnikа dobijeni su iz Protokola ispitanika za ubod of Epidemiology, Military Medical Academy, Belgrade. Results. krpelja Institutа zа epidemiologiju Vojnomedicinske The total number of collected ticks, the number of nymphs and аkаdemije u Beogradu. Rezultati. Ukupan broj prikupljenih the infection rates of the nymphs were significantly higher in for- krpelja, broj nimfi i stopa infekcije nimfi bili su značajno viši ests (p < 0.05) than park-forests and parks. Statistically, the ERI u šumama (p < 0,05) nego u park-šumama i parkovima. Utvr- value was significantly higher in forests than parks of Belgrade dili smo statistički značajno višu vrednost ERI u šumama ne- (χ2 = 7.78, p < 0.01). In March and July, the ERI value was also go u parkovima Beograda (χ 2 = 7,78, p < 0,01). U martu i ju- significantly higher in forests, than park-forests (p < 0.01) and lu, značajno viša vrednost ERI ustanovljena je u šumama ne- parks (p < 0.01). May was the month with the highest ERI value go u park-šumama (p < 0,01) i parkovima (p < 0,01). Maj je in each ecological category (forests p < 0.05; park-forests bio mesec sa najvišim vrednostima ERI u svakoj ekološkoj p < 0.01; parks p < 0.001). However, the number of tick bites in kategoriji (šume p < 0,05; park-šume p < 0,01; parkovi humans did not correlate with ERI values. Conclusion. The ob- p < 0,001). Broj uboda krpelja kod ljudi nije bio u korelaciji sa tained results indicate that the risk of tick bite and human expo- vrednostima ERI. Zaključak. Dobijeni rezultati pokazuju da sure to B. burgdorferi sensu lato is present at all selected localities in na svim odabranim lokalitetima Beograda postoji rizik od Belgrade. For a more comprehensive Lyme disease risk assess- uboda krpelja i ekspozicije ljudi B. burgdorferi. Za sveobuhvat- ment the method of entomological risk index assessment should niju procenu rizika od lajmske bolesti, metodu procene ERI be combined with other methods, taking into consideration all trebalo bi kombinovati sa drugim metodama, uzimajući u ob- tick stages and the behaviour and habits of people who may get zir sve stadijume krpelja, kao i ponašanje i navike ljudi, koji se infected B. burgdorferi sensu lato. mogu inficirati B. burgdorferi sensu lato. Key words: Ključne reči: ticks bites; ixodes; borrelia burgdorferi; lyme disease; krpelj, ubodi; ixodes; borrelia burgdorferi; lajmska prevalence; population density; health status indicators; bolest; prevalenca; populacija, gustina; zdravstveno serbia. stanje, indikatori; srbija. Correspondence to: Milena Krstić, Institute of Epidemiology, Sector for Preventive Medicine, Military Medical Academy, Belgrade, Serbia. Phone: +381 11 36 09 345. E-mail: [email protected] Page 818 VOJNOSANITETSKI PREGLED Vol. 73, No. 9 Introduction in people who were present at Belgrade's 19 localities inclu- ded in the study. The first case of human Lyme borreliosis (LB) in Serbia 1 was recorded in 1987 . The number of reported LB cases Methods has increased in the past decade. According to the reports from the Institute for Public Health of Serbia, a total of 3,860 The study was carried out in March-October 2009 in patients were registered in the period 2002–2007, with the Belgrade (Serbia). The research covered two stages of ticks, average annual incidence of 10.7/100 000. Between 2006 but only nymphs were used for calculating the entomological and 2008 more than 200 cases of LB were reported in Serbia. risk index (ERI). The majority of LB cases were found in Belgrade. In the pe- riod from 2000 to 2007, a total of 3,126 persons with tick Site selection bites were referred to the Institute of Epidemiology, Military Medical Academy in Belgrade 2. The study was carried out at 19 localities in Belgrade Due to the high number of LB cases in Belgrade, the classified in three ecological categories: forests (Lipovica, Program of Prevention and Chemical Fighting of Ticks was Bojčinska, Avala, Miljakovačka, Makiš), park-forests (Ada implemented in 1994. The application of preventive measures Ciganlija, Zvezdara, Banjica, Košutnjak, Jajinci) and parks (personal protection and landscape management) has priority (Hajd park, Bele vode, Usće, Šumice, Kalemegdan, Topči- in the Program, but according to some ecological and epide- der, Tašmajdan, Banovo brdo, Pionirski park). All three eco- miological criteria (an increasing number of tick bitten hu- logical categories have conditions for maintaining I. ricinus mans, an increasing incidence of LB, an increasing number of tick population. ticks and the infection rate of B. burgdorferi sensu lato), it is The parks predominately consisted of annual vegetation necessary to perform spraying of chemical insecticides for re- and brushes, although there was perennial vegetation, as duction of tick population in green surfaces such as forests, well. The basic characteristics of the areas were their connec- park-forests and parks. The chances of being bitten by a tick tion with the surrounding roads and the routine maintenance can be decreased by taking a number of precautions: avoid of the areas throughout the year (pruning trees, mowing tick-infected areas, walk on paths away from vegetation, wear lawns, removing leaves, litter accumulations, cut grass, light-coloured clothing so that ticks can be spotted more weeds and brush). These areas are also regularly visited by easily, conduct careful examination of your body and arrange pets and stray dogs. Finally, certain areas in parks are charac- for prompt removal of any ticks and use tick repellents for skin terized by favorable conditions for the appearance of rodents, or clothing. Moreover, to reduce the number of ticks in the squirrels, hedgehogs and birds, too. There are paths, benches surrounding nature it is recommended to remove leaves, litter, and gazebos for persons participating in recreational activiti- woodpiles, cut grass and brush from the area 3, 4. es in parks too. Investigations of ecology of B. burgdorferi sensu lato, Park-forests are slowly but surely, from year to year vectors and reservoirs in our environment have been conduc- changing in favor of parks. A park area is an ideal habitat for ted for more than 20 years. Ixodes ricinus (I. ricinus) was con- ticks, since rodents, lizards and birds live there, where forest firmed as a vector of LB in 1990 in former Yugoslavia 5. The areas are characterized by a big number of birds, small and first isolation of B. burgdorferi sensu lato from Apodemus fla- large rodents, reptiles and deer which also host B. burgdorfe- vicollis was performed 6. All the three patogens of the complex ri sensu lato. Park-forests are characterized by the abundan- B. burgdorferi sensu lato were isolated in Serbia: Borrelia ce of annual and perennial vegetation. sensu stricto, Borrelia afzelii and Borrelia garinii. The preva- Forests are covered by perennial deciduous forest ve- lence of B. burgdorferi sensu lato in I. ricinus ticks collected getation (oak, bitter oak, beech, dogwood, and timber), as in different regions in Serbia between 1990–2005 ranged as well as evergreen vegetation (pine juniper-tree), ivy, mis- follows: Zaječar 26.0 %, Pančevo 19.5%, Zrenjanin 19.8%, tletoe and annual vegetation. Forests are interspersed with Kraljevo 16.1%, Knjaževac 15.4% and Despotovac 33.3% 7. small clearings and roads leading to restaurants. Bojčinska Previous studies done in Belgrade estimate that the av- and Makiš forests are located near the Sava and Danube. erage infection of ticks with B. burgdorferi sensu lato was Throughout the woods there are paths for hikers and vehic- 21.9% 8. In the period from 2002 to 2007, the infection rate les. In the areas of Avala, Bojčinska, and Lipovička forests, of I.