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Borrelia burgdorferi infection surrounding La Crosse, Wis
S M Callister1, W A Agger, R F Schell
1Microbiology Research Laboratory, Gundersen Medical Foundation, La Crosse, Wisconsin 54601.
Abstract:
This investigation defined the extent of Borrelia burgdorferi infection surrounding La Crosse, Wis. White-footed mice, Peromyscus leucopus or P. maniculatis, were captured from sites in Wisconsin, Minnesota, and Iowa and cultured for B. burgdorferi to define the local boundaries of the midwestern Lyme disease area. All foci of B. burgdorferi infection (N1, N2, N3, and N4) were located north of interstate highway 90 except focus S2, which was south of the highway near Fort McCoy, Wis. The interstate highway may have been a barrier to deer movement which slowed the southward dispersal of Ixodes dammini. B. burgdorferi was isolated from 12 (63%) of the mice captured from site N4, which was adjacent to the western border of Fort McCoy. Unexpectedly, no B. burgdorferi-infected mice were isolated at site N0, located north of interstate highway 90 and enclosed by areas in which B. burgdorferi infection is endemic. This site is surrounded by natural barriers which may have slowed the spread of I. dammini by deer. The Wisconsin area in which B. burgdorferi is endemic should now include the surrounding area north of interstate highway 90 west from Fort McCoy to the Mississippi River. Additional studies are needed to define the rapidity, limits, and means of I. dammini dispersal into southern Wisconsin.
Insights
This study mapped Borrelia burgdorferi (Lyme disease) in the Midwest. Interstate 90 appears to limit the spread of infected ticks, but further research is needed.
Area of Science:
- Veterinary Entomology
- Epidemiology
- Infectious Diseases
Background:
- Lyme disease, caused by Borrelia burgdorferi, is a growing public health concern in the Midwestern United States.
- Understanding the geographic distribution of B. burgdorferi is crucial for effective prevention and control strategies.
Purpose of the Study:
- To define the local boundaries of the Lyme disease area in the Midwest.
- To investigate the potential role of natural and man-made barriers in the dispersal of Ixodes dammini ticks.
Main Methods:
- Capture of white-footed mice (Peromyscus leucopus/maniculatis) from various sites in Wisconsin, Minnesota, and Iowa.
- Culturing of captured mice for the presence of Borrelia burgdorferi.
- Geographic mapping of infection foci in relation to Interstate Highway 90 and natural barriers.
Main Results:
- All identified Borrelia burgdorferi infection foci (N1-N4) were located north of Interstate Highway 90, with one exception (S2) south of the highway near Fort McCoy, Wisconsin.
- The highway may act as a barrier to deer movement, potentially slowing the southward dispersal of Ixodes dammini.
- Borrelia burgdorferi was isolated from 63% of mice at site N4, adjacent to Fort McCoy's western border. Unexpectedly, no infected mice were found at site N0, north of I-90 but surrounded by endemic areas, suggesting natural barriers limited tick spread.
Conclusions:
- The endemic area for Borrelia burgdorferi in Wisconsin should be expanded to include regions north of Interstate Highway 90, west of Fort McCoy to the Mississippi River.
- Interstate Highway 90 and natural barriers may significantly influence the dispersal patterns of Ixodes dammini.
- Further research is necessary to determine the speed, extent, and mechanisms of Ixodes dammini dispersal into southern Wisconsin.