Distribution of the disease through the household 191 The first case in the family 194 Intimacy of family contact 197 Recurrent cases 198 SECTION V. IMMUNITY 199 SECTION VI. INFLUENZA AND OTHER DISEASES 212 Influenza and tuberculosis 212 Other infectious diseases 220 Encephalitis lethargica 222 SECTION VII. COMPARISON OF INFLUENZA WITH OTHER EPIDEMIC DISEASES 224 Epizootics 224 Asiatic cholera 228 Epidemic meningitis 228 Plague 229 Measles 231 SECTION VIII. THE PREVENTION AND CONTROL OF INFLUENZA 234 Anticipatory or preventive measures 236 Organization of health services 237 Palliative measures in the presence of an epidemic 239 Problems for the future. Constructive research 241 Bibliography 245 Footnote 1: From the Department of Preventive Medicine and Hygiene, Harvard Medical School, Boston, Mass. INFLUENZA. AN EPIDEMIOLOGIC STUDY. SECTION I. _General Epidemiologic Considerations._ Those who seek to find in a study of the epidemiology of epidemic influenza the secret of the causation of the disease, and its ultimate eradication, are probably predestined to at least partial failure. We must call upon the bacteriologist for information as to the causative organism, and in time he may be able to furnish us with satisfactory prophylactic measures, particularly with a successful vaccine.