Weil's disease has been recognized since Weil described the condition in 1886. Whether or not Weil's four cases were actually cases of spirochetal jaundice is not known, since laboratory confirmation was not possible then. Japanese investigators1 in 1916 published the results of their study of the disease in their country and established the identity of the causative organism, later named Leptospira icterohaemorrhagiae.2 Since 1916 cases have been reported from Europe, Asia, Africa, South America and North America and Australia.3 In the United States and Canada thirteen cases have been reported in which the etiologic agent was shown to be L. icterohaemorrhagiae.4 In these thirteen cases the clinical course did not differ materially from the usual course.5 In five cases the diagnosis was not made until autopsy.6
Some confusion exists in the diagnosis of Weil's disease, consisting chiefly in the differentiation of the disease from infectious jaundice. Weil's