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Volume 13, Number 11—November 2007
Letter

Lyme Disease in Urban Areas, Chicago

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To the Editor: Lyme disease is a multisystem illness caused by infection with the tickborne spirochete Borrelia burgdorferi. Most infections in the United States occur in the Northeast and upper Midwest, and the midwestern focus now includes Illinois (1,2). Previously, the greatest risk of contracting Lyme disease in the Midwest was confined to the northernmost states (Wisconsin and Minnesota) and did not encroach into heavily populated areas around the city of Chicago. However, we showed recently that B. burgdorferi–infected Ixodes scapularis ticks were recovered from sites in Cook and DuPage counties (3), but the percentages of infected ticks were low (<5%). Since that time, however, reports of Lyme disease in Cook County have been reviewed and individual I. scapularis tick submissions from Lake County, north of Chicago, have been received. We therefore surveyed new areas north of Chicago (closest was <1 mile from the city limits; farthest was ≈25 miles from the city limits) and examined additional ticks for infection with B. burgdorferi.

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Thumbnail of Sites surrounding Chicago from which Borrelia burgdorferi–infected Ixodes scapularis ticks were recovered in 2005–2006 (■) and 2006–2007 (●).

Figure. Sites surrounding Chicago from which Borrelia burgdorferi–infected Ixodes scapularis ticks were recovered in 2005–2006 (■) and 2006–2007 (●).

From December 2006 to May 2007, we collected 172 adult I. scapularis ticks from sites to the north and northwest of Chicago (Figure). Adult ticks were collected because nymphal ticks are more difficult to obtain, and the infection rate in adult ticks is similar (1). The tick midguts were removed aseptically, inoculated into tubes containing 1 mL of modified Barbour-Stoenner-Kelly medium (4), incubated at 35ºC, and examined for spirochetes for up to 3 weeks. Spirochetes were recovered from 21 (32%) of 65 ticks and 40 (37%) of 107 ticks collected from sites in Cook and Lake counties, respectively. In addition, PCR using primers specific for outer surface protein A (5) confirmed that the spirochetes were B. burgdorferi.

The findings demonstrate that the midwestern endemic focus of B. burgdorferi–infected I. scapularis now includes northern Cook and Lake counties. More importantly, the high percentage of B. burgdorferi–infected ticks in this region confirms a newly recognized significant risk of Lyme disease in suburban areas adjacent to Chicago (population ≈7 million). Recently, the Infectious Diseases Society of America recommended that clinicians consider prescribing a single prophylactic dose of doxycycline (200 mg) when patients have received tick bites in areas where the percentage of B. burgdorferi–infected I. scapularis exceeds 20% (6,7). The high percentage of infected adult ticks identified in this survey highlights the need for physicians in the Chicago area to become familiar with this recommendation, especially considering the high likelihood that nymphal I. scapularis ticks are similarly infected (1). Moreover, confirmation of the increasing risk of contracting Lyme disease near metropolitan Chicago should provide impetus for more comprehensive studies to completely define the risk of this potentially serious illness.

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Acknowledgment

We thank Joan Bestudik and Linn Haramis for initiating the studies; Joshua J. Nelson, K. Adam Nelson, Mark Hurley, and the North Park University parasitology class for tick collections; Steven Callister and Steven Lovrich for laboratory assistance; and Maria Vastis for secretarial support.

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Dean A. Jobe*, Jeffrey A. Nelson†Comments to Author , Michael D. Adam‡, and Stephen A. Martin§

Author affiliations: *Gundersen Lutheran Medical Center, La Crosse, Wisconsin, USA; †North Park University, Chicago, Illinois, USA; ‡Lake County Health Department and Community Health Center, Waukegan, Illinois, USA; §Cook County Department of Public Health, Oak Park, Illinois, USA

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References

  1. Nelson  JA, Bouseman  JK, Kitron  U, Callister  SM, Harrison  B, Bankowski  MJ, Isolation and characterization of Borrelia burgdorferi from Illinois Ixodes dammini. J Clin Microbiol. 1991;29:17324.PubMed
  2. Callister  SM, Nelson  JA, Schell  RF, Jobe  DA, Bautz  R, Agger  WA, Survey for Ixodes spp. and Borrelia burgdorferi in southeastern Wisconsin and northeastern Illinois. J Clin Microbiol. 1991;29:4036.PubMed
  3. jrn>Jobe DA, Lovrich SD, Nelson JA, Velat TC, Anchor C, Koeune T, et al. Borrelia burgdorferi in Ixodes scapularis ticks, Chicago area. Emerg Infect Dis. 2006;12:1039–41.<jrn>
  4. Callister  SM, Case  KL, Agger  WA, Schell  RF, Johnson  RC, Ellingson  JLE. Effects of bovine serum albumin on the ability of Barbour-Stoener-Kelly medium to detect Borrelia burgdorferi. J Clin Microbiol. 1990;28:3635.PubMed
  5. Nocton  JJ, Dressler  F, Rutledge  BJ, Rys  PN, Persing  DH, Steere  AC. Detection of Borrelia burgdorferi DNA by polymerase chain reaction in synovial fluid from patients with Lyme arthritis. N Engl J Med. 1994;330:22934. DOIPubMed
  6. Wormser  GP, Dattwyler  RJ, Shapiro  ED, Halperin  JJ, Steere  AC, Klempner  MS, The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006;43:1089134. DOIPubMed
  7. Nadelman  RB, Nowakowski  J, Fish  D, Falco  RC, Freeman  K, Mc Kenna  D, Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after Ixodes scapularis tick bite. N Engl J Med. 2001;345:7984. DOIPubMed

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Cite This Article

DOI: 10.3201/eid1311.070801

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Table of Contents – Volume 13, Number 11—November 2007

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Jeffrey A. Nelson, 3225 W. Foster Ave, Chicago, IL 60625, USA;

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Page created: July 06, 2010
Page updated: July 06, 2010
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The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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