Comparison of tick-borne microorganism communities in Ixodes spp. of the Ixodes ricinus species complex at distinct geographical regions.

Characterizing the tick-borne microorganism communities of Ixodes ricinus (sheep tick) and Ixodes persulcatus (taiga tick) from the I. ricinus species complex in distinct geographical regions of Eastern Europe and European Russia, we demonstrated differences between the two ticks. Taiga ticks were more frequently mono- and co-infected than sheep ticks: 24.4 % (45/184 tested ticks) versus 17.5 % (52/297) and 4.3 % (8/184) versus 3.4 % (10/297), respectively. Ginsberg co-infection index values were significant at the various sites. Diversity of the tick-borne microorganism communities was estimated by the Shannon index, reaching values of 1.71 ± 0.46 and 1.20 ± 0.15 at the sheep-tick and the taiga-tick harbored sites, respectively. Richness of the tick-borne microorganism community in the sheep tick collection sites was about twice the value of the taiga tick collection sites. Future investigations are warranted to further characterize the peculiarities of the tick-borne microorganism communities among the ticks of the Ixodes ricinus complex.

Detection of Babesia Sp. EU1 and members of spotted fever group rickettsiae in ticks collected from migratory birds at Curonian Spit, North-Western Russia.

To reveal the prevalence of spotted fever group (SFG) rickettsiae and Babesia sp. in Ixodes ricinus (L.) ticks from migratory birds, 236 specimens represented 8 species of Passeriformes and were collected at Curonian Spit in Kaliningrad enclave of North-Western Russia. The ticks (total 126) being detached from four bird species, Turdus philomelos, Fringilla coelebs, Parus major, and Sturnus vulgaris, were investigated by PCR using the primers Rp CS.877p/Rp CS.1258n for the detection of Rickettsia and BJ1/BN2 for Babesia spp. Babesia spp. were detected in 2 of 126 (1.6%) ticks. The partial sequence of 18S rDNA had 100% similarity to human pathogenic Babesia sp. EU1. The SFG rickettsiae were detected in 19 of 126 (15.1%) ticks collected from the above-mentioned bird species. BLAST analysis of SFG rickettsia gltA assigned sequences to human pathogenic Rickettsia helvetica (10.3%), Rickettsia monacensis (3.9%), and Rickettsia japonica (0.8%) with 98%-100% sequence similarity. The SFG rickettsiae and Babesia sp. EU1 in ticks collected from the passerines in Russia were detected for the first time. The survey indicates that migratory birds may become a reservoir for Babesia spp. and SFG rickettsiae. Future investigations need to characterize the role of birds in the epidemiology of these human pathogens in the region.

Tick-borne encephalitis virus in ticks in Finland, Russian Karelia and Buryatia.

Tick-borne encephalitis (TBE) is a central nervous system infection caused by a flavivirus [tick-borne encephalitis virus (TBEV)], transmitted by Ixodes ticks and endemic in a large region in Eurasia. We collected 2411 ticks from Finland and Russia in 2003-2008, screened them for TBEV by RT-PCR and isolated and analysed eight strains belonging to all three TBEV subtypes; in addition, we obtained two European-subtype strains from human serum samples. TBEV RNA prevalence in unengorged ticks was approximately 1 % both in the northernmost TBE-endemic areas of Europe in Finland and Russian Karelia, and in Siberia in Buryatia. In Finland, both Ixodes ricinus and Ixodes persulcatus ticks were found from distinct areas and, in Russian Karelia, were overlapping in the same study site. TBEV E and NS3 gene sequences obtained showed a variability of 0-4 % within European-subtype strains, 2-9 % for Siberian-subtype strains and 3-13 % for Far Eastern-subtype strains.

Enhancement of risk of tick-borne infection: environmental and parasitological aspects of the problem.

The appearance of phenotypic (and probably genetic) exoskeleton anomalies in Ixodes ticks, first discovered and described elsewhere, seems to be a global phenomenon clearly related to environment pollution by heavy metal ions. These external markers of cadmium accumulation in the tick indicate an enhanced risk of tick-borne infection related to an increased vectorial capacity. This manifests itself in the ability of infected ticks both to quest longer and to show increased locomotory activity (hunting) compared with normal ticks. Ticks with exoskeleton anomalies show a greater susceptibility to different microorganisms, including tick-borne pathogens, and more intense pathogen replication with a higher prevalence of multi-infection.

Siberian subtype tickborne encephalitis virus, Finland.

We isolated 11 Siberian subtype tickborne encephalitis virus (TBEV) strains from Ixodes persulcatus ticks from a TBEV-endemic focus in the Kokkola Archipelago, western Finland. Thus I. persulcatus and the Siberian TBEV are reported in a focus considerably northwest of their previously known range in eastern Europe and Siberia.

Evidence of Babesia microti infection in multi-infected Ixodes persulcatus ticks in Russia.

To detect Babesia-infected Ixodes persulcatus Shulze in a suburb of St. Petersburg, Russia, 738 adult ticks were studied using Babesia specific primers and PCR techniques. The entire sample (more than 1,200 individuals) was screened for the presence of Borrelia spp., Ehrlichia spp. and tick-borne encephalitis virus (TBEV). All 7 ticks infected with Babesia microti, were also infected with other pathogens (all 7 among 417 infected ticks, zero amongst the remaining 321 naive ones (chi2 = 5.25, p<0.05). Babesia microti occurred twice with Borrelia afzelii, 3 times with Borrelia garinii, once with both, and once with both B. garinii and TBEV. The prevalence of infection with Borrelia spp. was 34.0%, with Ehrlichia spp. 6.2%, with TBEV 1.5%, and with Ba. microti 0.9%. Babesia microti infection was not found in combination with Ehrlichia sp. or Borrelia burgdorferi sensu stricto. The latter pathogen (prevalence 2.6%), just like Ba. microti, was not encountered as a monoinfection. The data suggest that Ba. microti infection can only survive in I. persulcatus in combination with Borrelia spp. (7 of 7 infections). The disease in humans is more severe and longer-lasting when more than one pathogen is involved. Our observations show that the well known St. Petersburg focus of tick-borne encephalitis and Lyme disease is also a focus of ehrlichiosis and babesiosis.