Excerpt:

Members of the genus Borrelia are among the most common
infectious agents causing tick-borne disease in humans worldwide.
Here, we developed a Light Upon
eXtension(TM) (LUX) real-time PCR assay that can detect and
quantify Borrelia species in ticks that have fed on humans, and
we applied the assay to 399 such ticks. Borrelia PCR-positive
ticks were identified to species by sequencing the products of
conventional PCR performed using Borrelia group-specific primers.
There was a 19% prevalence of Borrelia spp. in the detached
ticks, and the number of spirochetes per Borrelia PCR-positive
tick ranged from 2.0 x 10(2) to
4.9 x 10(5) with a median of 7.8 x 10(3) spirochetes. Adult ticks
had a significantly larger number of spirochetes with a median of
8.4 x 10(4) compared to the median of nymphs 4.4 x 10(4). Adult
ticks also exhibited higher prevalence of Borrelia (33%) compared
to nymphs (14%). Among the identified species, Borrelia afzelii
was found to predominate (61%), followed by B. garinii (23%), B.
valaisiana (13%), B. burgdorferi sensu stricto (1%), B.
lusitaniae (1%), and B. miyamotoi-like (1%). Also, 3% of the
ticks were co-infected with multiple strains of B. afzelii.
Notably, this is the first report of B.
lusitaniae being detected in ticks in Sweden. 

Methods: Amplification of DNA sequences of Borrelia burgdorferi sensu lato by nested PCR from formalin-fixed and paraffin-embedded skin biopsies of morphea, GA and LSA, followed by automated sequencing of amplification products. PCR-based studies on Borrelia species in these disorders published until July 2009 were retrieved by a literature search.

Results: Borrelia DNA was detected in 3 of 112 skin biopsies (2.7%) including one of 49 morphea biopsies (2.0%), one of 48 GA biopsies (2.1%) and one of 15 LSA biopsies (6.6%). Amplification products belonged to B. burgdorferi sensu stricto in two cases available for sequence analysis.

Conclusions: The results of our and most of other PCR-based studies do not argue for a significant association of B. burgdorferi sensu lato with morphea, GA, LSA.

Journal of Cutaneous Pathology, 12/21/09

Passage through Ixodes scapularis ticks enhances the virulence of a weakly pathogenic isolate of Borrelia burgdorferi.

Adusumilli S, Booth CJ, Anguita J, Fikrig E. Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America; Section of Comparative Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America; Department of Veterinary and Animal Sciences, University of Massachusetts at Amherst, Amherst, Massachusetts, United States of America.

Lyme disease is the most common tick-borne illness in the United States. In this paper we explore the contribution of Ixodes scapularis ticks to the pathogenicity of Borrelia burgdorferi in mice. Previously we demonstrated that an isolate of B. burgdorferi sensu stricto (designated N40), passaged 75 times in vitro (N40-75), was infectious but no longer able to cause arthritis and carditis in C3H mice. We now show that N40-75 spirochetes can readily colonize I. scapularis and multiply during tick engorgement. Remarkably, tick-transmitted N40-75 spirochetes cause disease in mice. N40-75 spirochetes isolated from these animals also retained their pathogenicity when subsequently administered to mice via syringe inoculation. Array analysis revealed that several genes associated with virulence, including bba25, bba65, bba66, bbj09 and bbk32 had higher expression levels in the tick-passaged N40-75 spirochete. These data suggest that transmission of a high-passage attenuated isolate of B. burgdorferi by the arthropod vector results in generation of spirochetes that have enhanced pathogenesis in mice. PMID: 19822652 [PubMed – as supplied by publisher]=