Tick-borne pathogens in Ixodes ricinus ticks collected from migratory birds in southern Norway (original) (raw)
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Rickettsia helvetica in Ixodes ricinus ticks in Sweden
1999
In the present study further characterization of the amplified sequence of the citrate synthase gene of the spotted fever group Rickettsia isolated from Ixodes ricinus ticks in Sweden showed that it has 100% homology with the deposited sequence of the citrate synthase gene of Rickettsia helvetica. The restriction fragment length polymorphism (RFLP) pattern of an amplified 382-bp product of the citrate synthase sequence, defined by primers RpCS877 and RpCS1258, yielded fragments for our isolate that could be visualized as a double band that migrated at approximately 44 bp, another double band at 85 bp, and a single band at nearly 120 bp after digestion with the restriction enzyme AluI. When calculating a theoretical PCR-RFLP pattern of the sequence of the citrate synthase gene of R. helvetica from the known positions where the AluI enzyme cuts, we arrived at the same pattern that was obtained for our isolate, a pattern distinctly different from the previously published PCR-RFLP pattern for R. helvetica. Investigation of 125 living I. ricinus ticks showed a higher prevalence of rickettsial DNA in these ticks than we had found in an earlier study. Rickettsial DNA was detected by amplification of the 16S rRNA gene, for which a seminested primer system consisting of two oligonucleotide primer pairs was used. Of the 125 ticks, some were pooled, giving a total of 82 tick samples, of which 20 were found to be positive for the rickettsial DNA gene investigated. When considering the fact that some of the positive samples were pooled, the minimum possible prevalence in these ticks was 20 of 125 (16%) and the maximum possible prevalence was 46 of 125 (36.8%). These prevalence estimates conform to those of other studies of spotted fever group rickettsiae in hard ticks in Europe.
Ticks and Tick-borne Diseases, 2010
A total of 704 unfed ticks of the species Ixodes ricinus collected in Denmark were screened for Rickettsia DNA by a genus-specific real-time PCR. Of the nymphs, 4.7% (31/662) were positive for rickettsial DNA. Among the positive ticks, we observed a seasonal and habitat variation. The infection rate was highest in May as compared to July, August, and October. Ecotone (high tick density) showed an elevated prevalence as compared to spruce or beech forests. Sequencing revealed only DNA from R. helvetica.
Rickettsia spp. in Ixodes ricinus Ticks in Bavaria, Germany
Annals of the New York Academy of Sciences, 2006
This study aims to provide information on the occurrence of spotted fever rickettsiae in Ixodes ricinus ticks in southern Germany. A total of 2,141 I. ricinus ticks was collected in Bavaria. Pools of 5-10 ticks were studied by a PCR targeting the rickettsial citrate synthase gene gltA. The average prevalence rate was 12% (257 of 2,141). Sequencing data exclusively identified Rickettsia helvetica DNA. Results and other data demonstrate the possible role of R. helvetica in I. ricinus as a source of human infections in southern Germany.
Distribution of Rickettsia helvetica in Ixodes ricinus tick populations in Poland
International Journal of Medical Microbiology, 2008
Questing Ixodes ricinus ticks from different regions of Poland were investigated for the presence of spotted fever group (SFG) rickettsiae. A total of 1214 DNA samples of 2813 ticks, including 820 individual adult ticks and 394 pools containing 1993 nymphs, were tested by PCR for a fragment of the rickettsial gltA gene using the primers RpCs.877 and RpCs.1258. Overall, at least 5.5% ticks were found to be positive with the highest prevalence observed in females (10.6%). A sample of 14 positive PCR products was sequenced. Analyzed fragments of 270-370 bp showed 100% similarities to corresponding sequences of Rickettsia helvetica deposited in the GenBank. Results of our investigation confirm the occurrence and wide distribution of R. helvetica in I. ricinus tick populations in Poland. This rickettsia should be added to the list of potentially dangerous pathogens transmitted by ticks in our country.
First Detection of Rickettsia helvetica in Ixodes ricinus Ticks in Austria
Vector-Borne and Zoonotic Diseases, 2008
A total of 853 Ixodes ricinus ticks collected from the nine federal states of Austria were examined by molecular methods for possible infections with Rickettsia spp. It was shown that roughly one-third of the ticks were infected with Rickettsia spp. Moreover, Rickettsia helvetica was detected in Austria for the first time.
European Journal of Clinical Microbiology & Infectious Diseases, 2004
New Rickettsia spp. are continuously being isolated from ticks around the world, but in most cases their pathogenicity remains to be determined. Some rickettsiae first thought to be nonpathogenic have later been associated with human disease, such as Rickettsia slovaca [1], Rickettsia helvetica [2–4], Rickettsia aeschlimannii [5] and, more recently, the Spanish strain Bar29 (Rickettsia massiliae genogroup), which seems to play a role in the pathogenesis of Mediterranean spotted fever [6]. There are many other rickettsiae that, at least to date, have only been found in ticks, namely (i) genotypes IRS3/IRS4, first isolated in Ixodes ricinus ticks from Slovakia [7]; (ii) genotypes RpA4 and DnS14, DnS28, DnS79, DnS94 (belonging to the R. massiliae genogroup), which were first isolated, respectively, from Rhipicephalus pumilio and Dermacentor nutalli ticks from the former Soviet Union [8]; and more recently (iii) the spotted fever group rickettsiae detected in Dermacentor marginatus ticks c
Ticks and Tick-borne Diseases, 2013
The role of wild mammals in the dissemination and maintenance of Rickettsia in nature is still under investigation. European hedgehogs (Erinaceus europaeus) are often heavily infested by tick and flea species that are known to harbor and transmit different Rickettsia spp. We investigated ixodid ticks sampled from European hedgehogs for the presence of Rickettsia. A total of 471 Ixodes ricinus and 755 I. hexagonus were collected from 26 German and 7 British European hedgehogs. These were tested by a genus-specific real-time PCR assay targeting the citrate synthase gene (gltA). The rickettsia minimum infection rate was 11.7% with an increase detected with each parasitic tick stage. No significant difference in Rickettsia prevalence in the 2 Ixodes species was detected. Using sequencing of partial ompB, Rickettsia helvetica was the only species identified. More than half of the hedgehogs carried Rickettsia-positive ticks. In addition, tissue samples from 2/5 hedgehogs (where tissue DNA was available) were PCR-positive. These results show that European hedgehogs are exposed to R. helvetica via infected ticks and might be involved in the natural transmission cycle of this Rickettsia species.
Isolation of Rickettsia helvetica from ticks in Slovakia
Acta virologica, 2012
to date, only three rickettsial species have been found in ticks in Slovakia by serological and/ or molecular-biological techniques, namely Rickettsia slovaca, Candidatus rickettsia IrS, and Rickettsia raoultii. recently, we succeeded in isolation of the forth species, Rickettsia helvetica from Ixodes ricinus, the most frequent tick in Slovakia. The isolation, positive for 10% of tested ticks, was performed on Xtc cells by the shell-vial technique, Gimenez staining and light microscopy. The infected cell cultures contained rod-shaped particles morphologically identical to rickettsiae. The isolation was confirmed by direct detection of a fragment of the R. helvetica gene for citrate synthase in the positive ticks by Pcr and its subsequent cloning, sequencing and comparison with the database.
Molecular Investigations of Rickettsia helvetica Infection in Dogs, Foxes, Humans, and Ixodes Ticks
Applied and …, 2009
Rickettsia helvetica, a tick-borne member of the spotted-fever-group rickettsiae, is a suspected pathogen in humans; however, its role in animals is unknown. The aims of this study were to establish a R. helvetica-specific real-time TaqMan PCR assay and apply it to the analysis of tick vectors (to determine potential exposure risk) and blood samples from Canidae and humans (to determine prevalence of infection). The newly designed 23S rRNA gene assay for R. helvetica was more sensitive than a published citrate synthase gene (gltA) assay for several rickettsiae. Blood samples from 884 dogs, 58 foxes, and 214 human patients and 2,073 ticks (Ixodes spp.) collected from either vegetation or animals were analyzed. Although the maximal likelihood estimate of prevalence was 12% in unfed ticks and 36% in ticks collected from animals, none of the 1,156 blood samples tested PCR positive. Ticks from cats were more frequently PCR positive than ticks from dogs. Sequencing of the 23S rRNA and/or the gltA gene of 17 tick pools confirmed the presence of R. helvetica. Additionally, Rickettsia monacensis, which has not been previously found in Switzerland, was identified. In conclusion, R. helvetica was frequently detected in the tick population but not in blood samples. Nevertheless, due to the broad host range of Ixodes ticks and the high rate of infestation with this agent (i.e., R. helvetica was 13 times more frequent in unfed ticks than the tick-borne encephalitis virus), many mammals may be exposed to R. helvetica. The PCR assay described here represents an important tool for studying this topic.