Natural Occurrence and Characterization of the Lyme Disease Spirochete, Borrelia burgdorferi, in Cotton Rats (Sigmodon hispidus) from Georgia and Florida

Abstract

This is the first report of natural infection by Borrelia burgdorferi in the cotton rat Sigmodon hispidus. Nine B. burgdorferi isolates were obtained from ear tissues, urinary bladders, or both, by culturing tissues in BSKII medium. The rat from which the SI-3 isolate was cultured was from the same site (Sapelo Island, Georgia) as an infected cotton mouse Peromyscus gossypinus and Ixodes scapularis tick reported previously. The 8 B. burgdorferi isolates from rats in Florida included 1 (AI-1) from Amelia Island, 1 (FD-1) from Faver-Dykes State Park, and 6 (MI-3 through MI-8) from Merritt Island. The distance between Sapelo Island and Merritt Island is approximately 400 km. All B. burgdorferi isolates were characterized by indirect immunofluorescence using monoclonal antibodies to OspA (H3TS, H5332) and OspB (H5TS, H6831), polymerase chain reaction detection of specific B. burgdorferi B-31 DNA target sequences (ospA, fla, and a random chromosomal sequence), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of spirochetal proteins. The phenotypic and genotypic characteristics of the isolates are discussed, as well as the probable importance of the cotton rat as a reservoir for B. burgdorferi in the southern United States.

Genetic Heterogeneity ofBorrelia burgdorferiSensu Lato in the Southern United States Based on Restriction Fragment Length Polymorphism and Sequence Analysis

“…Experimentally, both species are efficient vectors in the laboratory (17,27). Several B. burgdorferi enzootic cycles exist in widely distributed foci in the South (18)(19)(20)(21)(22). Typical and atypical B. bissettii strains were identified in the present study.…”

Detection of Borrelia burgdorferi Sensu Stricto ospC Alleles Associated with Human Lyme Borreliosis Worldwide in Non-Human-Biting Tick Ixodes affinis and Rodent Hosts in Southeastern United States

“…There is a variety of vertebrate hosts, including small mammals and birds, that might serve as reservoir hosts for B. burgdorferi in the United States. However, in general, rodents appear to be the most common reservoir hosts in the North American regions where LD is endemic (2,28,34,52,63,64). Recent studies suggested that migration of infected vertebrate hosts may have a larger impact on the contemporary expansion of the pathogen population than the movement of tick vectors (54,57).…”

Delineation of a New Species of the Borrelia burgdorferi Sensu Lato Complex, Borrelia americana sp. nov

“…There I. minor, a non-humanbiting tick, appears to be more important in some areas as a maintenance vector in the enzootic cycle of B. burgdorferi sensu lato than the "bridge" vector I. scapularis (39; J. H. Oliver, Jr., C. W. Banks, K. L. Clark, and A. M. James, unpublished data). In addition to the major reservoir hosts, Peromyscus gossypinus and Sigmodon hispidus, the impact of the eastern wood rat Neotoma floridana, several bird species, and the vector I. minor in the enzootic cycles in the southeastern region was confirmed (41,42). There could be either several enzootic separate parallel cycles or overlapping cycles operating.…”