PMC

Variability of tick infection with R. Helvetica. R. helvetica-positive ticks from DK were divided per life stage and were expressed as a percentage per year (A) or per month (B). Monthly averages and standard deviations were calculated. In figure 2A, the percentage of infected adult ticks in 2006 is not representative, because only three adult ticks were caught. In other years between 12 and 26 adults were caught and tested.

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).