acquiring Lyme disease in the Chicago metropolitan region

".......clinicians and the public should be aware of the
possibility of acquiring Lyme disease in the Chicago metropolitan
region......."


http://www.cdc.gov/ncidod/EID/vol12no06/06-0306.htm

Letter

Borrelia burgdorferi in Ixodes scapularis Ticks, Chicago Area

Dean A. Jobe,* Steven D. Lovrich,* Jeffrey A. Nelson,?Comments Tom C.
Velat,? Chris Anchor,§ Tad Koeune,¶ and Stephen A. Martin, Jr#
*Gundersen Lutheran Medical Center, La Crosse, Wisconsin, USA; ?North
Park University, Chicago, Illinois, USA; ?Forest Preserve District of
DuPage County, Wheaton, Illinois, USA; §Forest Preserve District of
Cook
County, Elgin, Illinois, USA; ¶DuPage County Department of Health,
Wheaton, Illinois, USA; and #Cook County Department of Public Health,
Oak Park, Illinois, USA


To the Editor: Lyme disease is a multisystem disorder associated with
skin, myocardial, musculoskeletal, and central and peripheral nervous
system manifestations caused by infection with Borrelia burgdorferi
sensu lato spirochetes (1). In the United States, the illness is caused
by transmission of B. burgdorferi sensu stricto from the bite of
infected Ixodes scapularis (deer) ticks found primarily in the
northeastern and upper midwestern United States (2). B.
burgdorferi-infected ticks have also been recovered in portions of
northern Illinois but have not yet been reported in the Chicago region
(3). In fact, a previous survey (4) of forested areas in the heavily
populated regions immediately adjacent to Chicago confirmed a low risk
of contracting Lyme disease. Researchers failed to recover deer ticks
from 7 sampling sites and recovered only a single Borrelia isolate from
well-described B. burgdorferi sensu stricto rodent reservoirs (mice,
voles, chipmunks) captured from 5 sampling sites. A subsequent genetic
analysis confirmed the isolate was B. bissettii (5), a genomic group
that is likely nonpathogenic to humans in the United States.

However, the area of the Midwest where Lyme disease is endemic has
continued to expand from its origin in northeastern Minnesota and
northwestern Wisconsin (2,6). The Chicago metropolitan region has
numerous parks and natural areas that are biologically similar to the
known midwestern focus (7), and these areas support a large population
of white-tailed deer. Moreover, we have seen anecdotal reports of
persons with clinical signs and symptoms of Lyme disease and
epidemiologic evidence that suggests local acquisition. Two ticks
submitted by a resident who had hiked in DuPage County near the east
branch of the DuPage River were I. scapularis. We therefore began
searching for questing ticks in this area and 9 other geographically
diverse areas of DuPage County. The 10 sites were flagged by dragging
white cotton sheets through the underbrush for 2- to 10-hour intervals
during the spring of 2005. We timed these collections on the basis of
information that adult deer ticks were questing in Wisconsin. Recovered
ticks were placed in sealed vials and transported to the North Park
University Laboratory where their identity was confirmed. The midguts
were then removed aseptically, and each was placed into a separate vial
that contained 2 mL modified Barbour-Stoenner-Kelly medium that could
support the growth of small numbers of B. burgdorferi sensu stricto
(8).
Cultures were incubated for 6 weeks at 35°C and examined weekly for
spirochetes by darkfield microscopy.

Deer ticks were not found at 8 of the DuPage County sample sites.
However, 90 adult or nymphal I. scapularis were collected from the
remaining 2 sites, and spirochetes were recovered from 3 (3%) of the
tick midgut cultures. Because of these findings and anecdotal reports
of
deer ticks in Cook County, we also surveyed 3 sites in Cook County
during the fall of 2005. Deer ticks were not found at 2 sites, but 37
adult I. scapularis ticks were collected from a site in the
southwestern
portion of Cook County, and spirochetes were recovered from 2 (5%)
cultures.


Figure. Protein profiles of Borrelia burgdorferi sensu stricto (lane
A),
B. bissettii (lane B), and spirochetes...


We first examined the protein profiles to identify the spirochetes.
Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of
4
of the 5 isolates (1 isolate lost viability before analysis) showed
that
they were distinctly different from the B. bissettii isolate recovered
previously from Cook County (4), but the isolates were strikingly
similar to B. burgdorferi sensu stricto (Figure). We then amplified an
intergenic spacer region of the rrf-rrl portion of the rRNA from 2
isolates by a previously described method (9) and sequenced the
amplified products (sequencing by Laragen, Inc., Los Angeles, CA, USA).
The sequences were identical to that of B. burgdorferi sensu stricto
isolate B-31 (9).

The results confirmed that I. scapularis ticks infected with B.
burgdorferi sensu stricto were recovered from forested areas
surrounding
Chicago. Additional studies to define the extent and severity of the
risk are necessary, but clinicians and the public should be aware of
the
possibility of acquiring Lyme disease in the Chicago metropolitan
region.

Acknowledgments

We thank Joan Bestu*** and Linn D. Haramis for initiating the project;
John and Tammie Bouseman, Mike O'Driscoll, Curt Colwell, Barb O'Meara,
Peter Gianakis, Rachael Griffin, and our 16 student participants for
fieldwork; John Bouseman for tick identification; and Steve Callister
for guidance and manuscript review.

Partial funding for this work was received from the DuPage County
Health
Department (to J.A.N.).

References

1. Auwaerter PG, Aucott J, Dumler JS. Lyme borreliosis (Lyme disease):
molecular and cellular pathobiology and prospects for prevention,
diagnosis, and treatment. Expert Rev Mol Med. 2004;6:1-22.
2. Centers for Disease Control and Prevention. Lyme disease-United
States, 2001-2002. MMWR Morb Mortal Wkly Rep. 2004;53:365-8.
3. Nelson JA, Bouseman JK, Kitron U, Callister SM, Harrison B,
Bankowski
MJ, et al. Isolation and characterization of Borrelia burgdorferi from
Illinois Ixodes dammini. J Clin Microbiol. 1991;29:1732-4.
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al. Survey for Ixodes spp. and Borrelia burgdorferi in southeastern
Wisconsin and northeastern Illinois. J Clin Microbiol. 1991;29:403-6.
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SM, et al. CD4+ CD25+ T cells prevent arthritis associated with
Borrelia
vaccination and infection. Clin Diagn Lab Immunol. 2005;12:786-92.
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granulocytic ehrlichiosis agent. J Clin Microbiol. 2002;40:2070-3.
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scapularis in the north central United States. Emerg Infect Dis.
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8. Callister SM, Case KL, Agger WA, Schell RF, Johnson RC, Ellingson
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Effects of bovine serum albumin on the ability of
Barbour-Stoenner-Kelly
medium to detect Borrelia burgdorferi. J Clin Microbiol.
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9. Postic D, Ras NM, Lane RS, Henderson M, Baranton G. Expanded
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Microbiol. 1998;36:349-504.



Suggested citation for this article:
Jobe DA, Lovrich SD, Nelson JA, Velat TC, Anchor C, Koeune T, et al.
Borrelia burgdorferi in Ixodes scapularis ticks, Chicago area [letter].
Emerg Infect Dis [serial on the Internet]. 2006 Jun [date cited].
Available from http://www.cdc.gov/ncidod/EID/vol12no06/06-0306.htm

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