The book offered to the reader is the first in Russian literature to describe a number of therapeutic, surgical, oncological and other diseases that occur under the guise of infectious diseases. The logical stages of differential diagnosis of febrile conditions, rash, diarrhea, jaundice, hematological changes and other manifestations of infectious or somatic diseases are given. Intended for therapists, infectious disease specialists, surgeons, general practitioners and local doctors, as well as novice doctors who do not have sufficient clinical experience, and senior students of medical universities.