There occurred on Cape Cod, Massachusetts, during the summer of 1925 an epidemic of mild nature, characterized by the following symptoms, physical condition and course: generally a sudden onset with a rapidly rising temperature; pain of varying degree located in the abdomen, limbs, back, and especially over the lower ribs, increased by normal breathing; headache, chiefly about the eyes; general malaise; occasionally chilliness but never a "chill"; occasionally vomiting; rarely sore throat; never convulsion; an indefinite physical examination; persistence of these symptoms for a short time, varying from twelve or eighteen hours to one or three days, then remission of fever and general symptoms in turn lasting from twelve to thirty-six hours, followed by a "second peak" of temperature and recurrence of the same symptoms but less severe in character; final subsidence of the temperature to subnormal, with the patient considerably prostrated and entering on a slow convalescence prolonged out