The purpose of this study was evaluation of the prevalence of co-infection with Borrelia species, A. phagocytophilum and Babesia spp. in patients with tick-borne encephalitis (TBE). At total of 110 patients with TBE were included in the study. Serological tests for tick-borne encephalitis virus (TBEV), PCR for Borrelia species, Anaplasma phagocytophilum and Babesia spp., blood smears for A. phagocytophilum and Babesia spp. and BLAST analysis for Babesia spp. were performed. Results showed a significant majority of patients co-infected with Borrelia species (30/110; 27 %), much less with A. phagocytophilum (12/110; 10.9 %) and with Babesia spp. (1/110; 0.9 %). The BLAST analysis of the 18S rDNA sequence obtained with the Babesia spp. specific primers indicated that the patient was infected with Babesia microti. Triple co-infections (TBEV-Borrelia species- A. phagocytophilum) were observed in three (3/110; 2.7 %) patients. Conclusions were such that differential diagnosis in patients after the tick bite, presenting with acute symptoms, should include not only TBE and Lyme disease, but also other diseases transmitted by ticks. In patients with low parasitemia in suspicion of Babesia spp. infection PCR seems to be a more sensitive method than blood smear. Co-infection with various tick-borne pathogens must be always considered, especially in endemic regions.

The incidence of tick-borne encephalitis showed a dramatic spike in several countries in Europe in 2006, a year that was unusually cold in winter but unusually warm and dry in summer and autumn. In this study we examine the possible causes of the sudden increase in disease: more abundant infected ticks and/or increased exposure due to human behaviour, both in response to the weather.

Ticks were collected from the vegetation in the Baltic countries Estonia, Latvia, Lithuania and eastern Poland and analyzed for the presence of tick-borne encephalitis virus (TBEV) by amplification of the partial E and NS3 genes. In Estonia we found statistically significant differences in the TBEV prevalence between I. persulcatus and I. ricinus ticks (4.23% and 0.42%, respectively). In Latvia, the difference in TBEV prevalence between the two species was not statistically significant (1.02% for I. persulcatus and 1.51% for I. ricinus , respectively). In Lithuania and Poland TBEV was detected in 0.24% and 0.11% of I. ricinus ticks, respectively. Genetic characterization of the partial E and NS3 sequences demonstrated that the TBEV strains belonged to the European subtype in all countries, as well as to the Siberian subtype in Estonia. We also found that in areas where ranges of two tick species overlap, the TBEV subtypes may be detected not only in their natural vector, but also in sympatric tick species.