Source : Webster's Revised Unabridged Dictionary (1913)

Weil's disease \Weil's disease\ (Med.)
   An acute infectious febrile disease, resembling typhoid
   fever, with muscular pains, disturbance of the digestive
   organs, jaundice, etc.

Source : WordNet®

Weil's disease
     n : a severe form of leptospirosis in human beings