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Ixodes ricinus ticks are reservoir hosts for Rickettsia helvetica and potentially carry flea-borne Rickettsia species.

Sprong H, Wielinga PR, Fonville M, Reusken C, Brandenburg AH, Borgsteede F, Gaasenbeek C, van der Giessen JW - Parasit Vectors (2009)

Bottom Line: IRS and R. bellii-like were found.Besides R. helvetica, unexpected rickettsiae are found in I. ricinus ticks.We propose that I. ricinus is a major reservoir host for R. helvetica, and that vertebrate hosts play important roles in the further geographical dispersion of rickettsiae.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and Environment (RIVM), Antonie van Leeuwenhoeklaan 9, P,O, Box 1, Bilthoven, the Netherlands. Joke.van.der.Giessen@rivm.nl.

ABSTRACT

Background: Hard ticks have been identified as important vectors of rickettsiae causing the spotted fever syndrome. Tick-borne rickettsiae are considered to be emerging, but only limited data are available about their presence in Western Europe, their natural life cycle and their reservoir hosts. Ixodes ricinus, the most prevalent tick species, were collected and tested from different vegetation types and from potential reservoir hosts. In one biotope area, the annual and seasonal variability of rickettsiae infections of the different tick stages were determined for 9 years.

Results: The DNA of the human pathogen R. conorii as well as R. helvetica, R. sp. IRS and R. bellii-like were found. Unexpectedly, the DNA of the highly pathogenic R. typhi and R. prowazekii and 4 other uncharacterized Rickettsia spp. related to the typhus group were also detected in I. ricinus. The presence of R. helvetica in fleas isolated from small rodents supported our hypothesis that cross-infection can occur under natural conditions, since R. typhi/prowazekii and R. helvetica as well as their vectors share rodents as reservoir hosts. In one biotope, the infection rate with R. helvetica was ~66% for 9 years, and was comparable between larvae, nymphs, and adults. Larvae caught by flagging generally have not yet taken a blood meal from a vertebrate host. The simplest explanation for the comparable prevalence of R. helvetica between the defined tick stages is, that R. helvetica is vertically transmitted through the next generation with high efficiency. The DNA of R. helvetica was also present in whole blood from mice, deer and wild boar.

Conclusion: Besides R. helvetica, unexpected rickettsiae are found in I. ricinus ticks. We propose that I. ricinus is a major reservoir host for R. helvetica, and that vertebrate hosts play important roles in the further geographical dispersion of rickettsiae.

No MeSH data available.


Related in: MedlinePlus

Occurrence of Rickettsia spp. in The Netherlands. Left: Map of the Netherlands showing the five locations that were sampled for this study. Right: Genetic variation of Rickettsia species found in The Netherlands. The phylogenetic relationship was based on a part of the 16SrRNA sequence: base 41 until 383 of R. prowazekii. The evolutionary distance values were determined by the method of Jukes and Cantor, and the tree was constructed according to the neighbor joining method. Cophenetic correlation coefficients, which are lower than 89%, are indicated at the nodes. 16SrRNA sequences from R. SP. IRS (L36102), IRS2 (DQ100164), IRS3 (AF141907) IRS4 (AF141908), rickettsii (L36217), helvetica (L36212), conorii (L36105), sibirica (L36218), canadensis (L36104), prowazekii (U29135), typhi (M20499), massiliae (L36106), bellii (L36103), felis (DQ102712), akari (L36099), and australis (L36101) were from Genbank. Between brackets the regions where the Rickettsia species were identified (AL = Ameland; BW = Bijlmerweide; DK = Duin en Kruidberg; HO= Heumesoord; HV= Houtvesterijen). No names are given to Rickettsia (sub)species which are not identical to the sequences in Genbank(e.g. AL-ticks).
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Figure 1: Occurrence of Rickettsia spp. in The Netherlands. Left: Map of the Netherlands showing the five locations that were sampled for this study. Right: Genetic variation of Rickettsia species found in The Netherlands. The phylogenetic relationship was based on a part of the 16SrRNA sequence: base 41 until 383 of R. prowazekii. The evolutionary distance values were determined by the method of Jukes and Cantor, and the tree was constructed according to the neighbor joining method. Cophenetic correlation coefficients, which are lower than 89%, are indicated at the nodes. 16SrRNA sequences from R. SP. IRS (L36102), IRS2 (DQ100164), IRS3 (AF141907) IRS4 (AF141908), rickettsii (L36217), helvetica (L36212), conorii (L36105), sibirica (L36218), canadensis (L36104), prowazekii (U29135), typhi (M20499), massiliae (L36106), bellii (L36103), felis (DQ102712), akari (L36099), and australis (L36101) were from Genbank. Between brackets the regions where the Rickettsia species were identified (AL = Ameland; BW = Bijlmerweide; DK = Duin en Kruidberg; HO= Heumesoord; HV= Houtvesterijen). No names are given to Rickettsia (sub)species which are not identical to the sequences in Genbank(e.g. AL-ticks).

Mentions: To investigate the presence of rickettsiae and the possible emergence of Rickettsia species in the Dutch tick population, 1735 ticks were collected between 2000 and 2008 (Table 1) from 5 geographically different locations (Figure 1 left). Ticks from Bijlmerweide (BW), Koninklijke Houtvesterijen (HV), Duin en Kruidberg (DK), and Heumesoord (HO) were collected by blanket dragging [27]. BW is a typical city park near Amsterdam with many deciduous trees and a few shrubs with a rich secondary vegetation. HV is an oak forest where ninety percent of the area is covered with blueberries. DK is a dune area rich in vegetation were several species of deciduous trees and shrubs were present, and 60% of the soil was covered with vegetation litter. HO is a typical heather area which consisted of heather only, with a single pine tree and very little vegetation litter. Only very scarce and incomplete information is available about the fauna present in these areas. Ticks from Ameland (AL) originated from humans who were bitten by ticks on the isle in the Wadden Sea, and who had gone to the local general practitioner for removal of the tick [28].


Ixodes ricinus ticks are reservoir hosts for Rickettsia helvetica and potentially carry flea-borne Rickettsia species.

Sprong H, Wielinga PR, Fonville M, Reusken C, Brandenburg AH, Borgsteede F, Gaasenbeek C, van der Giessen JW - Parasit Vectors (2009)

Occurrence of Rickettsia spp. in The Netherlands. Left: Map of the Netherlands showing the five locations that were sampled for this study. Right: Genetic variation of Rickettsia species found in The Netherlands. The phylogenetic relationship was based on a part of the 16SrRNA sequence: base 41 until 383 of R. prowazekii. The evolutionary distance values were determined by the method of Jukes and Cantor, and the tree was constructed according to the neighbor joining method. Cophenetic correlation coefficients, which are lower than 89%, are indicated at the nodes. 16SrRNA sequences from R. SP. IRS (L36102), IRS2 (DQ100164), IRS3 (AF141907) IRS4 (AF141908), rickettsii (L36217), helvetica (L36212), conorii (L36105), sibirica (L36218), canadensis (L36104), prowazekii (U29135), typhi (M20499), massiliae (L36106), bellii (L36103), felis (DQ102712), akari (L36099), and australis (L36101) were from Genbank. Between brackets the regions where the Rickettsia species were identified (AL = Ameland; BW = Bijlmerweide; DK = Duin en Kruidberg; HO= Heumesoord; HV= Houtvesterijen). No names are given to Rickettsia (sub)species which are not identical to the sequences in Genbank(e.g. AL-ticks).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2743653&req=5

Figure 1: Occurrence of Rickettsia spp. in The Netherlands. Left: Map of the Netherlands showing the five locations that were sampled for this study. Right: Genetic variation of Rickettsia species found in The Netherlands. The phylogenetic relationship was based on a part of the 16SrRNA sequence: base 41 until 383 of R. prowazekii. The evolutionary distance values were determined by the method of Jukes and Cantor, and the tree was constructed according to the neighbor joining method. Cophenetic correlation coefficients, which are lower than 89%, are indicated at the nodes. 16SrRNA sequences from R. SP. IRS (L36102), IRS2 (DQ100164), IRS3 (AF141907) IRS4 (AF141908), rickettsii (L36217), helvetica (L36212), conorii (L36105), sibirica (L36218), canadensis (L36104), prowazekii (U29135), typhi (M20499), massiliae (L36106), bellii (L36103), felis (DQ102712), akari (L36099), and australis (L36101) were from Genbank. Between brackets the regions where the Rickettsia species were identified (AL = Ameland; BW = Bijlmerweide; DK = Duin en Kruidberg; HO= Heumesoord; HV= Houtvesterijen). No names are given to Rickettsia (sub)species which are not identical to the sequences in Genbank(e.g. AL-ticks).
Mentions: To investigate the presence of rickettsiae and the possible emergence of Rickettsia species in the Dutch tick population, 1735 ticks were collected between 2000 and 2008 (Table 1) from 5 geographically different locations (Figure 1 left). Ticks from Bijlmerweide (BW), Koninklijke Houtvesterijen (HV), Duin en Kruidberg (DK), and Heumesoord (HO) were collected by blanket dragging [27]. BW is a typical city park near Amsterdam with many deciduous trees and a few shrubs with a rich secondary vegetation. HV is an oak forest where ninety percent of the area is covered with blueberries. DK is a dune area rich in vegetation were several species of deciduous trees and shrubs were present, and 60% of the soil was covered with vegetation litter. HO is a typical heather area which consisted of heather only, with a single pine tree and very little vegetation litter. Only very scarce and incomplete information is available about the fauna present in these areas. Ticks from Ameland (AL) originated from humans who were bitten by ticks on the isle in the Wadden Sea, and who had gone to the local general practitioner for removal of the tick [28].

Bottom Line: IRS and R. bellii-like were found.Besides R. helvetica, unexpected rickettsiae are found in I. ricinus ticks.We propose that I. ricinus is a major reservoir host for R. helvetica, and that vertebrate hosts play important roles in the further geographical dispersion of rickettsiae.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and Environment (RIVM), Antonie van Leeuwenhoeklaan 9, P,O, Box 1, Bilthoven, the Netherlands. Joke.van.der.Giessen@rivm.nl.

ABSTRACT

Background: Hard ticks have been identified as important vectors of rickettsiae causing the spotted fever syndrome. Tick-borne rickettsiae are considered to be emerging, but only limited data are available about their presence in Western Europe, their natural life cycle and their reservoir hosts. Ixodes ricinus, the most prevalent tick species, were collected and tested from different vegetation types and from potential reservoir hosts. In one biotope area, the annual and seasonal variability of rickettsiae infections of the different tick stages were determined for 9 years.

Results: The DNA of the human pathogen R. conorii as well as R. helvetica, R. sp. IRS and R. bellii-like were found. Unexpectedly, the DNA of the highly pathogenic R. typhi and R. prowazekii and 4 other uncharacterized Rickettsia spp. related to the typhus group were also detected in I. ricinus. The presence of R. helvetica in fleas isolated from small rodents supported our hypothesis that cross-infection can occur under natural conditions, since R. typhi/prowazekii and R. helvetica as well as their vectors share rodents as reservoir hosts. In one biotope, the infection rate with R. helvetica was ~66% for 9 years, and was comparable between larvae, nymphs, and adults. Larvae caught by flagging generally have not yet taken a blood meal from a vertebrate host. The simplest explanation for the comparable prevalence of R. helvetica between the defined tick stages is, that R. helvetica is vertically transmitted through the next generation with high efficiency. The DNA of R. helvetica was also present in whole blood from mice, deer and wild boar.

Conclusion: Besides R. helvetica, unexpected rickettsiae are found in I. ricinus ticks. We propose that I. ricinus is a major reservoir host for R. helvetica, and that vertebrate hosts play important roles in the further geographical dispersion of rickettsiae.

No MeSH data available.


Related in: MedlinePlus