Leptospirosis Cases in the Tokyo Metropolitan Area, Japan

In Japan, 20-50 cases of leptospirosis are reported annually, typically involving farmers or returnees from tropical areas. Here, we report on 5 indigenous leptospirosis cases that occurred in the Tokyo urban area. All patients were men (mean age, 66.4 +/- 4.6 [SD] years) and presented with clinical features that included high fever, acute kidney injury, and jaundice. Three patients presented with pulmonary infiltration and ground-glass opacity on admission. Two of the 5 patients were intubated and underwent continuous hemodiafiltration. The mean length of hospitalization was 38.0 +/- 17.0 days, and all patients were treated successfully with antibiotics. Notably, all patients had a history of exposure to rats prior to becoming symptomatic, suggesting that exposure to rats is a risk factor for urban leptospirosis. Although rare, even in metropolitan areas, leptospirosis should be considered by physicians when patients present with severe sepsis, acute kidney injury, and a history of exposure to rats.