Open AccessPopulation Structure of the Lyme Borreliosis Spirochete Borrelia burgdorferi in the Western Black-Legged Tick ( Ixodes pacificus ) in Northern California
Author(s) -
Yvette A. Girard,
Bridgit Travinsky,
Anna M. Schotthoefer,
Natalia Fedorova,
Rebecca J. Eisen,
Lars Eisen,
Alan G. Barbour,
Robert S. Lane
Publication year - 2009
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01704-09
Subject(s) - borrelia burgdorferi , biology , tick , lyme disease , ixodes scapularis , ixodes , population , genotype , borrelia , relapsing fever , ixodidae , virology , genetics , gene , demography , sociology , antibody
Factors potentially contributing to the lower incidence of Lyme borreliosis (LB) in the far-western than in the northeastern United States include tick host-seeking behavior resulting in fewer human tick encounters, lower densities ofBorrelia burgdorferi -infected vector ticks in peridomestic environments, and genetic variation amongB. burgdorferi spirochetes to which humans are exposed. We determined the population structure ofB. burgdorferi in over 200 infected nymphs of the primary bridging vector to humans,Ixodes pacificus , collected in Mendocino County, CA. This was accomplished by sequence typing the spirochete lipoproteinospC and the 16S-23S rRNA intergenic spacer (IGS). ThirteenospC alleles belonging to 12 genotypes were found in California, and the two most abundant,ospC genotypes H3 and E3, have not been detected in ticks in the Northeast. The most prevalentospC and IGS biallelic profile in the population, found in about 22% of ticks, was a newB. burgdorferi strain defined byospC genotype H3. Eight of the most commonospC genotypes in the northeastern United States, including genotypes I and K that are associated with disseminated human infections, were absent in Mendocino County nymphs.ospC H3 was associated with hardwood-dominated habitats where western gray squirrels, the reservoir host, are commonly infected with LB spirochetes. The differences inB. burgdorferi population structure in California ticks compared to the Northeast emphasize the need for a greater understanding of the genetic diversity of spirochetes infecting California LB patients.