Isolation of Lyme disease Borrelia from puffins (Fratercula arctica) and seabird ticks (Ixodes uriae) on the Faeroe Islands

Phylogeographic relationships of Ixodes uriae (Acari: Ixodidae) and their significance to transequatorial dispersal of Borrelia garinii

The seabird tick Ixodes uriae (Acari: Ixodidae) has a bi- and circumpolar distribution and is commonly infected with Lyme disease Borrelia. Identical Borrelia flagellin gene sequences have been detected in I. uriae from both the Northern and Southern Hemispheres, suggesting a transequatorial transport of Borrelia. Parsimony analysis of the internal transcribed spacer 2 (ITS2) and a part of 16S rDNA of I. uriae from the Northern and Southern Hemispheres indicated that northern and southern I. uriae might be reproductively separated. We hypothesize that Borrelia is probably not dispersed from one hemisphere to the other by ticks attached to seabirds.

Host association of Borrelia burgdorferi sensu lato--the key role of host complement

Borrelia burgdorferi sensu lato (s.l.), the tick-borne agent of Lyme borreliosis, is a bacterial species complex comprising 11 genospecies. Here, we discuss whether the delineation of genospecies is ecologically relevant. We provide evidence that B. burgdorferi s.l. is structured ecologically into distinct clusters that are host specific. An immunological model for niche adaptation is proposed that suggests the operation of complement-mediated selection in the midgut of the feeding tick. We conclude that vertebrate hosts rather than tick species are the key to Lyme borreliosis spirochaete diversity.

Induced maternal response to the Lyme disease spirochaete Borrelia burgdorferi sensu lato in a colonial seabird, the kittiwake Rissa tridactyla

Mothers are predicted to invest in their offspring depending on the quality of their mate, their opportunity to invest in future reproduction and the characteristics of the habitat in which their offspring will be born. Recent studies have suggested a transfer of maternal immunity to offspring as an induced response to the local presence of parasites in the environment, but evidence has been indirect. Here, we show the presence of antibodies against the Lyme disease agent Borrelia burgdorferi sensu lato, a spirochaete transmitted by the seabird tick Ixodes uriae, in the eggs of kittiwakes Rissa tridactyla. We report higher prevalence of antibodies against Borrelia in eggs from breeding areas with higher prevalence and abundance of ticks. Further, high repeatabilities of antibody-positive eggs within clutches and between first and replacement clutches show that, within a breeding season, females differ consistently with respect to the expression of this induced maternal response. Our results suggest that mothers can alter investment in their young depending on local conditions. Such maternal effects clearly have implications for the ecology and evolution of host-parasite interactions.

Ecology of Borrelia burgdorferi in ticks (Acari: Ixodidae), rodents, and birds in the Sierra Nevada foothills, Placer County, California

This study examined the prevalence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner in host-seeking adult and nymphal Ixodes pacificus Cooley & Kohls and estimated the I. pacificus infestation and B. burgdorferi infection of rodent and avian hosts in the western Sierra Nevada foothills of northern California. Additionally, we identified species likely to participate in an enzootic cycle for B. burgdorferi in this yellow pine transition habitat. Evidence of infection with B. burgdorferi was identified in 7.3 and 5.4% of host-seeking I. pacificus adults and nymphs, respectively. Mean numbers of I. pacificus observed on rodents were 1.15 for Neotoma fuscipes Baird and 0.18 for Peromyscus spp. One of 104 ear punch tissues obtained from woodrats and none from 49 Peromyscus spp. yielded B. burgdorferi. A total of 291 collected birds representing 34 species had a mean of 0.27 I. pacificus per bird. The mean I. pacificus infestation of ground-dwelling birds was 2.5 ticks per bird. Forty-nine of 92 (53%) blood smears collected from birds were reactive to a B. burgdorferi specific antibody. This study presents the identification of a B. burgdorferi-like spirochete in birds in western North America. The tick burden and spirochete infection of birds suggests that birds may be involved in a local B. burgdorferi enzootic cycle and likely participate in the transport of ticks and spirochetes to other locations while rodents from this site do not appear to be major contributors.

Genetic diversity of Borrelia burgdorferi sensu lato in ticks from mainland Portugal

To date Borrelia lusitaniae is the only genospecies of Borrelia burgdorferi sensu lato isolated from Ixodes ricinus ticks collected in Portugal and Tunisia. This suggests that the genospecies diversity of B. burgdorferi sensu lato decreases toward the southwestern margin of its Old World subtropical range. In order to further explore the genetic diversity of B. burgdorferi sensu lato from this region, 55 I. ricinus and 27 Hyalomma marginatum questing adults, collected during the spring of 1998 from a sylvatic habitat south of Lisbon, Portugal, were analyzed. Infection prevalences of 75% in I. ricinus ticks and 7% in H. marginatum ticks were detected by a nested PCR that targets the rrf (5S)-rrl (23S) spacer of B. burgdorferi sensu lato. Restriction fragment length polymorphism (RFLP) analysis of the I. ricinus-derived amplicons showed that the sequences in the majority of samples were similar to those of B. lusitaniae type strains (76% for strain PotiB1, 5% for strain PotiB3). Two novel RFLP patterns were obtained from 12% of the samples. The remaining 7% of samples gave mixed RFLP patterns. Phylogenetic analysis of rrf-rrl spacer sequences revealed a diverse population of B. lusitaniae in questing adult I. ricinus ticks (the sequences did not cluster with those of any other genospecies). This population consisted of 10 distinct sequence types, suggesting that multiple strains of B. lusitaniae were present in the local I. ricinus population. We hypothesize that B. lusitaniae has a narrow ecological niche that involves host species restricted to the Mediterranean Basin.