Presence of Bartonella spp. in Ixodidae ticks

Abstract

Ixodes ricinus and Dermacentor reticulatus are common European ticks and vectors of various infections. Bartonella spp. is an aetiologic agent of vector-borne infections. Bartonella henselae transmission by cat fleas is now well established, and new potential vectors have recently been identifled, including ticks and biting flies. The presence of Bartonella spp. was searched for in adult I. ricinus and D. reticulatus ticks collected from infested animals and vegetation. The studies were performed on 447 ticks. Two hundred and forty-two adult I. ricinus ticks, including 165 removed from animals and 77 collected from vegetation, were tested. All but one of the studied 205 adult D. reticulatus ticks came from vegetation; one was removed from a cow. The ticks were collected in various parts of Poland: central (Warsaw and suburbs), eastern (Bialowieza forest, Biala Podlaska) and southern (Radomsko). All ticks collected from vegetation were unfed. Among 165 Ixodes ricinus ticks collected from animals, 60 were engorged, 48 partly engorged and 55 unfed. Tick samples were stored at –70°C until DNA isolation by Qiagen columns (QIAamp DNA Mini Kit; Qiagen, Hilden, Germany). DNA was extracted from each tick in accordance with the manufacturer's protocol for tissue samples after homogenisation of the arthropod. All D. reticulatus ticks were crushed in Eppendorf tubes first and then DNA extraction was performed by boiling in 200 μL of 0.7 M NH4OH for 30 min. Molecular detection and identification of Bartonella spp. DNA was based on citrate synthase gene (gltA) fragment amplification, which enables identification of a few Bartonella species, as previously published [1Norman AF Regenery R Jameson P Greene C Krause DC Differentiation of Bartonella-like isolates at the species level by PCR-restriction fragment length polymorphism in the citrate synthase gene.J Clin Microbiol. 1995; 33: 1797-1803PubMed Google Scholar]. PCR products were purified with the QIAquick PCR Purification Kit (Qiagen). The amplicons were sequenced with the ABI 377 DNA Analyzer (Applied Biosystem, Forester City, CA, USA). Database searches and sequence comparisons were performed with the BLAST search engines provided by the National Center for Biotechnology Information. Bartonella spp. DNA was detected in nine of 242 I. ricinus ticks, and in one of 205 D. reticulatus specimens. The frequency of Bartonella spp. in two studied species of ticks differed significantly. The majority of studied D. reticulates ticks were sampled from vegetation, whereas I. ricinus ticks were removed from both vegetation and animals. All of the nine I. ricinus ticks, in which Bartonella spp. DNA was detected, were removed from animals: eight from dogs and one from a cow. Four were engorged, four partly engorged and one unfed. The nucleotide sequence of the amplified fragments of the gltA gene from eight I. ricinus ticks were 99–100% homologous to sequences reported as B. henselae. In case of amplicon from one tick we got over 95% of homology with uncultured Bartonella sp. reported from I. tasmani and I. scapularis ticks. A D. reticulatus tick that was positive for Bartonella spp. DNA was collected from vegetation in Czerniakowski Park in Warsaw. A sequence of PCR-derived DNA fragment demonstrated 84% similarity with the sequence of Bartonella quintana DQ383817.1 (Table 1).TABLE 1Characteristics of ticks in which DNA of Bartonella spp. was detectedTick NoSpecies of tickStatus of the ticksPCRMolecular identification of amplicon (% similarities with known sequences of Bartonella – GenBank number)Date of ticks collectionPlace of collectionArea of collection13DD. reticulatusUnfedPositiveB. quintana (84%DQ383817.1)April 2007VegetationWarsaw8R*The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.I. ricinusPartly engorgedPositiveB. henselae (100%AM294994.1)April 2007DogRadomsko10R*The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.I. ricinusPartly engorgedPositiveB. henselae (100%AM294993.1)April 2007DogRadomsko39R*The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.I. ricinusPartly engorgedPositiveBartonella spp.(97%EU247522.1)#The amplicon from the tick demonstrated 97% similarities to uncultured Bartonella sp. reported from I. tasmani.April 2007DogRadomsko70KI. ricinusEngorgedPositiveB. henselae (99%AM294994.1)September 2007CowBiala Podlaska28I. ricinusEngorgedPositiveB. henselae (99%AM294994.1)May 2005DogWarsaw56I. ricinusEngorgedPositiveB. henselae (99%BX897699.1)October 2005DogWarsaw49I. ricinusPartly engorgedPositiveB. henselae (99%BX897699.1)October 2005DogWarsaw30*The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.I. ricinusEngorgedPositiveB. henselae (100%AM294993.1)May 2005DogWarsaw37*The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.I. ricinusUnfedPositiveB. henselae (99%BX897699.1)May 2005DogWarsaw* The ticks were removed from a heavily infested dog. Only one specimen from all those collected was Bartonella PCR-positive.# The amplicon from the tick demonstrated 97% similarities to uncultured Bartonella sp. reported from I. tasmani. Open table in a new tab Three dogs were infested by more than one tick. In two animals B. henselae PCR-positive ticks were found in one of few ticks collected simultaneously. In the third dog, DNA of uncultured Bartonella sp. isolate and DNA of B. henselae were detected from two different ticks. The results obtained in this survey suggest that transmission of Bartonella species may be carried out by ticks. I. ricinus ticks seem to play the most important role in this process, especially because this species is distributed throughout Poland, whereas D. reticulatus is limited to the northeastern part of Poland. So far a few representatives of genus Bartonella have been detected in ticks; among them B. vinsonii subsp. berkhoffii, B. quintana, B. henselae and a group described as uncultured Bartonella have been mentioned [1Norman AF Regenery R Jameson P Greene C Krause DC Differentiation of Bartonella-like isolates at the species level by PCR-restriction fragment length polymorphism in the citrate synthase gene.J Clin Microbiol. 1995; 33: 1797-1803PubMed Google Scholar, 2Chomel B Boulouis HJ Maruyama S Breitschwerdt EB Bartonella spp. in pets and effect on human health.Emerg Infect Dis. 2006; 12: 389-393Crossref PubMed Scopus (306) Google Scholar, 3Halos L Jamal T Maillard R et al.Evidence of Bartonella sp. in questing adult and nymphal Ixodes ricinus ticks from France and co-infection with Borrelia burgdorferi sensu lato and Babesia sp.Vet Res. 2005; 36: 79-87Crossref PubMed Scopus (84) Google Scholar]. The results of our study are concordant as we detected in studied ticks B. quintana, B. henselae and uncultured Bartonella spp. What seems interesting is that despite the fact that the majority (80%) of Bartonella PCR-positive ticks were removed from dogs, we have not detected B. vinsonii subsp. berkhoffii. The results of our studies confirm the prevalence of Bartonella spp. in ticks at a percentage lower than 10%; however, the frequency differs in I. ricinus and D. reticulatus ticks, being 4% vs. 0.5% [2Chomel B Boulouis HJ Maruyama S Breitschwerdt EB Bartonella spp. in pets and effect on human health.Emerg Infect Dis. 2006; 12: 389-393Crossref PubMed Scopus (306) Google Scholar, 3Halos L Jamal T Maillard R et al.Evidence of Bartonella sp. in questing adult and nymphal Ixodes ricinus ticks from France and co-infection with Borrelia burgdorferi sensu lato and Babesia sp.Vet Res. 2005; 36: 79-87Crossref PubMed Scopus (84) Google Scholar, 4Sanogo YO Zeaiter Z Caruso G et al.Bartonella henselae in Ixodes ricinus ticks (Acari:Ixodida) removed from humans, Belluno province, Italy.Emerg Infect Dis. 2003; 9: 329-332Crossref PubMed Scopus (104) Google Scholar]. The presence of Bartonella spp. is reported in various species of ticks from all over the world. To confirm the hypothesis that D. reticulatus ticks are competent vectors of Bartonella, fed ticks should be examined. Because in our study only a few I. ricinus ticks fed on the same animal were infected with Bartonella spp., this may suggest that these bacteria are transmitted transtadially, as has been recently shown by Cotte et al. [5Cotte V Bonnet S Le Rhun DL et al.Transmission of Bartonella henselae by Ixodes ricinus.Emerg Infect Dis. 2008; 7: 1074-1080Crossref Scopus (166) Google Scholar]. The existence of the bacteria of genus Bartonella in ticks and their role in transmission of bartonellosis is an open issue, which needs further investigation. This work was partially supported by the MNISW project N303 047 31/1487.