Sporadic Urban Leptospirosis

15 November 1996 | Volume 125 Issue 10 | Pages 794-798

Background: Surprisingly, many inner-city residents have antibodies to Leptospira interrogans. The manner in which these persons acquire this organism in the absence of recognized occupational, recreational, or epidemic risk factors is not known.

Objective: To study the epidemiology of patients with leptospirosis who acquired L. interrogans in inner-city Baltimore, Maryland.

Design: Epidemiologic investigation.

Setting: Inner-city university hospital.

Patients: Three inner-city residents who developed leptospirosis.

Measurements: Trapping rats in alleys where the patients may have acquired L. interrogans; polymerase chain reaction (PCR) analysis of patient serum and cerebrospinal fluid specimens and rat tissues to determine the presence of leptospiral DNA; and serologic testing of serum from patients and rats by microagglutination assay to confirm L. interrogans infection.

Results: Three patients developed leptospirosis after probable percutaneous exposure to rat (Rattus norvegicus) urine in Baltimore alleys. A PCR assay detected L. interrogans DNA in samples of body fluid obtained from the first two patients at presentation (one in cerebrospinal fluid, the other in serum). Results of PCR done on serum drawn from the third patient after antibiotic therapy began were negative. A microagglutination test showed that all patients had high levels of antibodies to the L. interrogans serogroup lcterohaemorrhagiae. In 19 of 21 rats that were trapped in the alleys where the patients had sustained lacerations before illness developed, kidney or brain tissues were positive by PCR for the presence of L. interrogans.

Conclusions: A population was discovered to be at risk for acquiring L. interrogans: urban residents who are sporadically exposed to rat urine in the inner city. Inner-city rats often carry L. interrogans. Polymerase chain reaction can quickly establish the diagnosis of leptospirosis and is useful for epidemiologic study. An endemic substrate for the transmission of the organism is present in inner-city Baltimore. Leptospirosis may become increasingly recognized in deteriorating inner cities in which rat populations are expanding.

Author and Article Information

From Johns Hopkins School of Medicine and Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland; and the National Institutes of Health, Bethesda, Maryland.
Acknowledgments: The authors thank Sandra Bragg, PhD, of the CDC for doing microagglutination testing on patients and rats. They also thank John Bartlett, MD, for unfailing support; Richard Spiegel, DVM, MPH, for helpful discussions; Ilan Wittstein, MD, for referring patient 3; Lawrence Gardner, MD, Derek Fine, MD, Tonya Adams, MD, and the Osler Medical Housestaff for care of the patients described in this report; Thomas Templeton, PhD, for preparing oligonucleotides; Rodney Willoughby, MD, for retaining the cerebrospinal fluid specimen of patient 1; Lena Trivedi, PhD, for doing screening leptospiral serologic testing; Thomas Quinn, MD, and Charlotte Gaydos, DrPH, for use of laboratory resources; and Jonathan Hirsch and Aaron Meisner for assistance in catching vermin. They also thank Harold D. Standiford, MD, and the Maryland Chapter of the American College of Physicians for generous support.
Grant Support: Dr. Vinetz is a Howard Hughes Medical Institute Physician Postdoctoral Fellow.
Requests for Reprints: Joseph M. Vinetz, MD, National Institute of Allergy and Infectious Diseases, Laboratory of Parasitic Diseases, 9000 Rockville Pike, Building 4, Room 126, Bethesda, MD 20892-0425.
Current Author Addresses: Dr. Vinetz: National Institute of Allergy and Infectious Diseases, Laboratory of Parasitic Diseases, 9000 Rockville Pike, Building 4, Room 126, Bethesda, MD 20892-0425.