Rare Disease Penetrates Baltimore

As if America's inner cities aren't troubled enough, now they have a newly recognized problem to contend with: leptospirosis. A report in today's Annals of Internal Medicine has shown that living in an inner city is a risk factor for the disease.

Leptospirosis is a disease with symptoms ranging from mild aches and pains to jaundice, meningitis, kidney failure, and in rare cases death. Caused by the bacterium Leptospira interrogans, which infects a range of animals, the disease is known and diagnosed primarily in the tropics. A leptospirosis outbreak in Nicaragua last fall sickened thousands of people, killing 20.

Cases in the United States are unusual, although the disease is probably underreported because its symptoms are often attributed to other causes. Such was the case when a "very sick woman" showed up at Johns Hopkins Medical Center in November 1993, says Johns Hopkins infectious disease specialist Joseph Vinetz. Her symptoms--severe jaundice and meningitis--baffled the doctors. Then, Vinetz recalls, "I literally woke up in the middle of the night and thought she had leptospirosis."

Vinetz's team learned that the patient had walked barefoot in inner-city alleys in Baltimore where she had seen rats, and that she had cut her foot 10 days earlier. Subsequent investigations revealed two other Baltimore patients with leptospirosis who had also been in rat-infested alleys.

What particularly surprised Vinetz was that none of the patients had been in the countryside--most previous cases of leptospirosis in the United States have been associated with exposures to infected animals through activities such as camping or farming. Vinetz presumed that his patients had been infected by the rats, and his suspicions were apparently confirmed when his team found L. interrogans in 19 of 21 rats trapped in alleys where the patients had been.

"Leptospirosis in urban areas is not a new problem," says Richard Speigel, an epidemiologist at the Centers for Disease Control and Prevention. However, he says, "it's probably greatly underdiagnosed." Besides confusion stemming from the disease's symptoms, there is no simple lab test to confirm a diagnosis. But the disease is not going to go away, says Vinetz: "Many inner cities are in worse and worse condition."