The present studies on Phlebotomus and Carrión's disease were begun when the writer came to Peru as a member of the Harvard 1937 Expedition to Peru. He returned to Lima at the end of 1937 to continue the work under the joint auspices of Harvard Medical School and the National Institute of Hygiene and Public Health, later becoming a member of the Institute's staff.
Carrión's disease is widely known under the names of its two chief clinical forms, namely Oroya fever, a severe, usually fatal, anemia, and verruga peruana, or simply verruga, usually benign and characterized by a cutaneous eruption of hemangioma-like nodules. In Peru it is common to include both forms of the disease under the term la verruga. The disease is endemic in a narrow strip along the Pacific slope and in certain other parts of the Peruvian Andes between Latitudes 6 and 13 degrees South and at altitudes usually between 800 and 3000 meters.