![]() The high level of habitat variation in northwestern California presents a varied risk for Borrelia-associated tick-borne disease in humans because of diverse variations in vertebrate reservoir ecology, tick abundance, and human exposure to ticks. bissettii, a species recently implicated as a human pathogen in Mendocino County, California ( 10). ![]() burgdorferi was found more frequently in woodland habitats, but it was also detected in a grassland–chaparral habitat several hundred meters from the nearest woodland. miyamotoi among its prevalence measures ( 5). pacificus ticks ( 6) the study did not, however, differentiate between Borrelia spp. burgdorferi in nearby Santa Cruz County recreational areas reported an infection prevalence of ≈6% among adult I. miyamotoi was detected at 7/12 sites, and prevalence ranged from 0.7% to 7.5%. burgdorferi sensu lato was detected (4/12 sites each), prevalence was 0.6%–2.2% and 0.7%–2.5%, respectively. pacificus ticks at all 12 sites from which tick sample sizes exceeded 30. that cause tick-borne relapsing fever in the United States ( B. The sequences for our samples from California and those for isolates from the eastern United States ( 9) and Japan ( 8) formed a monophyletic clade that was oriented as a sister clade to the 3 Borrelia spp. miyamotoi (on the basis of alignments of 503 bp). burgdorferisensu lato (both on the basis of alignments of 816 bp), and 14 were B. We obtained intergenic spacer sequence data for 27 of the positive samples 6 samples were B. sequences available from GenBank.įrom a total of 1,180 adult ticks, we found 43 samples positive for Borrelia spp., resulting in a minimum infection prevalence of 3.6% ( Table). BLAST ( ) was used to compare each sequence to other Borreliaspp. The nested PCR product was further purified by using the QIAquick Kit (QIAGEN) and then sequenced (Environmental Genetics and Genomics Laboratory, Northern Arizona University, Flagstaff, AZ, USA by using capillary Sanger sequencing on an ABI 3730 sequencer (Life Technologies, Grand Island, NY, USA). genotype, we attempted to sequence the 16S–23S ( rrs-rrlA) intergenic spacer of each sample positive by qPCR ( 8). DNA was analyzed by qPCR, with use of primer and fluorescent hybridization probes previously developed to differentiate Borrelia spp. DNA was extracted from ticks by using the DNeasy Blood and Tissue Kit (QIAGEN, Valencia, CA, USA) according to the manufacturer’s protocols and then stored at −20☌ until use. from positive pools as the minimum infection prevalence (i.e., assuming 1 positive tick/positive pool). ![]() We interpreted the prevalence of Borrelia spp. ![]() Ticks were pooled for examination by quantitative PCR (qPCR) for the presence of Borrelia spp. Habitat varied from chaparral and grassland to coastal live oak woodland. pacificus ticks by dragging a 1-m 2 white flannel blanket along vegetation and/or leaf litter in 12 recreational areas in the San Francisco Bay area during January–May 2012 ( Table). ecology in California, we collected adult I. burgdorferi if the diagnostics were for spirochetes (e.g., direct fluorescent antibody tests or dark-field microscopy) or genetically targeted for Borrelia spp. miyamotoi infections among measures of B. Other studies may have unintentionally included B. miyamotoi, which is more closely related to spirochetes that cause relapsing fever, has also been detected in 2 locations in California ( 1, 2) and has recently been implicated as a human pathogen in the northeastern United States ( 3, 4). To the Editor: In northwestern California, USA, the western black-legged tick, Ixodes pacificus, is a known vector of Borrelia burgdorferi, the spirochete that causes Lyme disease. Salkeld, Stephanie Cinkovich, and Nathan C. Tick-borne Pathogens in Northwestern California, USA ĭaniel J. ![]()
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