Prevalence ofBorrelia burgdorferiSensu Lato Infection Among Rodents and Host-Seeking Ticks in South Carolina

Abstract

Tissues of rodents and host-seeking adult ticks collected in the Piedmont, Sandhills, Coastal Plain, and Coastal Zone of South Carolina were cultured in attempts to isolate Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt & Brenner), the etiologic agent of Lyme disease. An exploratory, tree-based statistical analysis was used to identify ecological variables that were associated with spirochete infection among rodents and ticks. Spirochetes were isolated from tissues of 71 rodents: 22 (69%) of 32 eastern woodrats, 39 (53%) of 74 cotton mice, and 11(25%) of 44 hispid cotton rats. Rodent infection prevalences were significantly higher in the Coastal Zone than in other regions. Spirochetes were also cultured from 31 (2.6%) of 1,193 questing ticks. Prevalence of spirochetes in Ixodes affinis Neumann (19/74, 26%) was significantly higher than in I. scapularis Say (12/864, 1.3%) and other species (0/255) of ticks tested. In addition, two (9%) of 23 adult I. minor Neumann removed from woodrats contained spirochetes. Isolates from rodents and ticks were analyzed immunologically by indirect immunofluorescence and Western blots, and further characterized by polymerase chain reaction assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All were determined to be B. burgdorferi sensu lato. Results of this study confirmed that B. burgdorferi is endemic in South Carolina, and that enzootic transmission cycles exist at foci in the Coastal Zone. These findings add additional evidence that I. affinis and I. minor are potentially significant maintenance vectors of the spirochete.

Borrelia Species in Host-Seeking Ticks and Small Mammals in Northern Florida

“…Although they are much less aggressive in biting humans in this region, I. scapularis ticks are also infected with B. burgdorferi sensu lato strains and could occasionally transmit them to people. The prevalence of infection in adult I. affinis ticks in Florida based on PCR testing (31%) was similar to that found in South Carolina (25.7%) by using culture isolation (11). However, this tick species is not known to bite humans and probably is important only in the enzootic transmission of the spirochete among small mammals, which are the preferred hosts for the immature tick stages (10).…”

“…Only 1.3% in South Carolina were infected, based on BSK culture results (11). The present study also identified a very high B. burgdorferi sensu lato infection prevalence (85%) among small mammals from two sites near the Atlantic Coast in northeast Florida.…”

“…The present study also identified a very high B. burgdorferi sensu lato infection prevalence (85%) among small mammals from two sites near the Atlantic Coast in northeast Florida. This is higher than the rates determined for small mammals in South Carolina, Georgia, and Florida in previous studies (11,37). Interestingly, if infection prevalence data from a previous study (37) for cotton mice, cotton rats, and wood rats, three established small mammal reservoir species in the Southeast, are combined from all sites within those three states and compared, a potential trend is apparent.…”

Variation in the Microbiota of Ixodes Ticks with Regard to Geography, Species, and Sex

“…B. burgdorferi has been detected in 35 to 50% of I. scapularis ticks in the northeastern states (4) but is rarely found in ticks in the southern United States (5)(6)(7)(8)(9). In contrast, 63% of I. affinis ticks were found to have Borrelia DNA by PCR (10).…”

<strong><strong></strong></strong><p align="justify">Observations on the seasonality of <em>Ixodes scapularis </em>Say in Mississippi, U.S.A.</p><strong></strong>

“…Primarily as a result of Lyme disease, the seasonality and life cycle of I. scapularis have been well studied in the northeastern and central U.S.; however, less is known about the biology of this tick in the southern U.S. (Clark et al 2002, Goddard 1992, 1993, Oliver 1993, Mackay & Foil 2005, Goddard & Piesman 2006. For example, in a 10-year survey of human-biting ticks in Mississippi, I. scapularis was responsible for 9.2% of reported human tick bites, making it the fourth most Article common tick found on humans in Mississippi (Goddard 2002), and in Florida, Georgia and South Carolina, I. scapularis was commonly collected in several studies (Felz et al 1996, Cilek & Olson 2000.…”