Borrelia burgdorferi sensu lato and Ehrlichia spp. in Ixodes ticks from southern Norway.

We report the results of a study of the prevalence of Ehrlichia and Borrelia species in 341 questing Ixodes ricinus ticks from two locations in southern Norway. The prevalences of Borrelia burgdorferi sensu lato and Ehrlichia spp. were, respectively, 16 and 11.5% at site 1 and 17 and 6% at site 2. Prevalence and species composition of Borrelia and Ehrlichia varied with location and date of collection. The dominant Borrelia species at both sites was Borrelia afzelii, followed by Borrelia burgdorferi sensu stricto. Borrelia garinii was found in only a single tick. The dominant member of the Ehrlichia group was a recently described Ehrlichia-like organism related to the monocytic ehrlichiae. Variants of Ehrlichia phagocytophila and the agent of human granulocytic ehrlichiosis were also found. The highest prevalences for B. afzelii, B. burgdorferi sensu stricto, and the Ehrlichia-like organism were observed in May. B. afzelii was most prevalent in females, less prevalent in nymphs, and least prevalent in males, while the prevalence of Ehrlichia was highest in nymphs, lower in females, and least in males. Double infections with B. afzelii and B. burgdorferi sensu stricto and with B. afzelii and the Ehrlichia-like organism were significantly overrepresented. Tick densities were highest in May, when densities of more than 200 ticks/100 m2 were observed, and declined during the summer months to densities as low as 20 ticks/100 m2. We conclude that estimates of the prevalence of tick-borne bacteria are sensitive to the choice of date and site for collection of ticks. This is the first study of tick-borne Borrelia and Ehrlichia in Norway and the lowest reported B. garinii prevalence in Northern Europe. The prevalence of the Ehrlichia-like organism is described for the first time in questing ticks.

Clonal distribution of invasive Neisseria meningitidis isolates from the Norwegian county of Telemark, 1987 to 1995.

Forty-two Neisseria meningitidis isolates were obtained from patients with meningococcal disease in the Norwegian county of Telemark (January 1987 to March 1995), and all were compared by PCR amplicon restriction endonuclease analysis (PCR-AREA) of the dhps gene, chromosomal DNA fingerprinting, and serological analysis. PCR-AREA divided the isolates into 11 classes, of which 4, comprising 15, 8, 6, and 2 isolates, were clonal while the remaining 8 classes were genetically heterogeneous or contained only 1 isolate. Three of the four clonal classes could be tentatively equated with recognized epidemic clones (ET5, ET37, and cluster A4) on the basis of their phenotypic characteristics, while the remaining clone appears to be new. There were significant differences in the geographical distribution of clones, with class 1 (ET5-like) isolates significantly overrepresented in rural parts of Telemark. Class 1 (ET5-like) isolates occurred throughout the study period and were dominant in 1987. Class 2 (ET37-like) isolates occurred from 1988 to 1992, and class 3 isolates (with no recognizable ET affinities) were found only in 1991 and 1992.