42 Christova and Komitova, Clinical and epidemiological features of Lyme borreliosis in Bulgaria Wien Klin Wochenschr (2004) 116/1–2: 42–46 © Springer-Verlag 2004 wiener klinische wochenschrift the middle european journal of medicine Printed in Austria Original Article Summary. Introduction: Data on disease expression and epidemiological characteristics of Lyme borreliosis in south-eastern Europe are scarce. Patients: To reveal features of Lyme borreliosis in Bulgaria, clinical data and epidemiological characteristics of 1257 patients reported between 1999 and 2002 were analysed. Results: The most affected age group was 5–9 years, followed by 45–49 years, 50–54 years, and 10–14 years. Most of the patients (68%) lived in a rural area or were attacked by ticks during activities in a rural area. Lyme borreliosis cases occurred throughout the year with two peaks – one in June and second smaller one in Septem- ber. The most common clinical manifestation was erythe- ma migrans (EM), diagnosed in 868 (69.1%) of the pa- tients. Rashes had a median diameter of 11 cm and were predominantly located on lower extremities. Forty-four per cent of the rashes consisted of homogenous erythe- ma and 56% had central clearing. Multiple EM was de- tected in 4.3% of the EM cases. Neuroborreliosis was the second most common presentation of Lyme borreliosis, diagnosed in 19% of the patients. Lyme arthritis was found in 8% of the patients. Heart and ocular manifesta- tions were recorded in 1.1% and 0.9% of the patients, respectively. Borrelial lymphocytoma and acrodermatitis chronica atrophicans were very rare (0.3%). Twenty- seven patients (2.1%) had multiple organ involvement. Conclusions: The results of the study show that the epidemiology and clinical manifestations of Lyme borre- liosis in Bulgaria are similar to those in the majority European countries but possess some distinguishing characteristics. Key words: Lyme borreliosis, Borrelia burgdorferi, disease expression, clinical symptoms, epidemiology. Introduction Lyme borreliosis is considered as the most common human tick-borne disease in Europe and the USA [1]. It is caused by bacteria of the Borrelia burgdorferi sensu lato complex. At least eleven genospecies belong to the complex, although the first three are predominantly asso- ciated with clinical manifestation of borreliosis [2–5]. A wide spectrum of clinical manifestations is attributed to Lyme borreliosis. The disease affects the skin, nervous system, joints, heart, and eyes. An association exists be- tween different clinical manifestations of the disease and various Borrelia genospecies. B. afzelii is associated with acrodermatitis chronica atrophicans, B. garinii with neu- rological disorders, and B. burgdorferi sensu stricto with arthritis [6–9]. All three genospecies cause erythema mi- grans (EM). The prevalence of various clinical manifesta- tions of Lyme borreliosis differs among countries or re- gions. Except for EM, the clinical hallmark of Lyme borreliosis, disease expressions are not specific and need laboratory confirmation. Routine laboratory diagnosis of Lyme borreliosis is serological and, according to the two- step approach, a sensitive ELISA or IFA test is recom- mended as a first step and immunoblot as a second step to confirm positive and borderline results from the first assay [10]. Data on disease expression and epidemiology of Lyme borreliosis are available from different parts of Europe, but as yet such data from south-eastern Europe are scarce. Bulgaria is endemic for Lyme borreliosis and is a country with mandatory notification of the disease. The reported incidence of Lyme borreliosis in Bulgaria is over 6/100 000 population, but the true incidence is most prob- ably much higher, not only because the disease often is self-limited and mild cases go unrecognised but also be- cause of the limited facilities of laboratories in Bulgaria for serological diagnosis. The objectives of this study were to reveal the clinical and epidemiological features of Lyme borreliosis in Bulgaria. For this purpose, the available clinical and sero- logical data of patients diagnosed with Lyme borreliosis between 1999 and 2002 were analysed, together with patients’ epidemiological characteristics. Patients and methods Patients: This study was based on analysis of physi- cian-diagnosed, laboratory-confirmed (except for EM) re- ported cases of Lyme borreliosis in Bulgaria, 1999–2002. Clinical, epidemiological and serological data were col- lected for a total of 1257 patients diagnosed within the Clinical and epidemiological features of Lyme borreliosis in Bulgaria Iva Christova 1 and Radka Komitova 2 1 National Reference Laboratory for Lyme borreliosis, Department of Microbiology, National Center of Infectious and Parasitic Diseases, Sofia, and 2 Department of Infectious Diseases, Medical University, Plovdiv, and Department of Infectious Diseases, Medical University, Sofia, Bulgaria