Two cases of Weil's disease with acute renal failure in the central Tokyo metropolitan area.

The incidence of leptospirosis, or Weil's disease, in developed countries, particularly in temperate regions, has been dramatically decreasing due to recent improvements in the hygienic environment. In these areas, physicians rarely face this disease and inclusion as a differential diagnosis of acute renal failure seems increasingly uncommon. However, we encountered two cases of severe leptospirosis requiring hemodialysis in central Tokyo. Both cases showed hyperbilirubinemia, thrombocytopenia and mental disturbance in addition to acute renal failure. Severe leptospirosis remains associated with high mortality rates, and early clinical suspicion and laboratory confirmation of the disease are crucial. Detailed history-taking suggested that leptospirosis was caused by transmission from rats in both cases. Rodents inhabit most land areas, implying that the disease can occur all over the world, even in huge metropoles such as Tokyo. These two cases indicate the need for awareness of leptospirosis among physicians working even in urban areas of developed countries.