Relapsing Fever Group Borrelia in Southern California Rodents

[CanLyme note: Lyme disease is a borreliosis, caused by many strains/species of Borrelia. Relapsing fever is simply strain related Lyme disease (borreliosis)]

Journal of Medical Entomology 51(5):1029-1034. 2014 

ABSTRACT

Wild rodent reservoir host species were surveyed prospectively for infection with Borrelia hermsii, the causative agent of tick-borne relapsing fever in the western United States. Trapping occurred during the summer of 2009–2012 at field sites surrounding Big Bear Lake, CA, a region where human infection has been reported for many years. Using quantitative polymerase chain reaction (qPCR), we tested 207 rodents from 11 species and found chipmunks (Tamias spp.) and a woodrat (Neotoma macrotis) infected. Chipmunks represented the majority of captures at these sites. Sixteen of the 207 (7.7%; CI = 4.6–12.4) animals were qPCR-positive for Borrelia spp. associated with relapsing fever, and of those, we obtained bacterial DNA sequences from eight. The phylogram made from these sequences depict a clear association with B. hermsii genomic group I. In addition, we identified an infection withBorrelia coriaceae in a Tamias merriami, a potentially nonpathogenic member of the tick-borne relapsing fever group. Our findings support the hypothesis that chipmunk species play an important role in the maintenance of Borrelia species that cause tick-borne relapsing fever in the western United States, and therefore the risk of infection to people.

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