1. Introduction.- 2. Discovery of the Organisms.- 2.1. Life of Alexandre Yersin (18631943).- 2.1.1. Youth and Education.- 2.1.2. Paris: Influence of Pasteur, Work with Roux on Diphtheria.- 2.1.3. The Orient: Explorations in Indochina.- 2.1.4. Discovery of the Plague Bacillus.- 2.1.5. The YersinKitasato Controversy.- 2.1.6. Further Work on Plague.- 2.1.7. Other Activities.- 2.1.8. Final Years.- 2.2. Nomenclature.- 2.3. History of Yersinia enterocolitica and Yersinia pseudotuberculosis.- 2.4. The Life and Work of K. F. Meyer (18841974).- References.- 3. Epidemiology.- 3.1. Plague.- 3.1.1. Cycles of Transmission.- 3.1.2. World Distribution of Human Plague.- 3.1.3. Plague in Vietnam.- 3.1.4. Plague in Burma.- 3.1.5. Plague in Brazil.- 3.1.6. Plague in the United States.- 3.1.7. Plague in Indonesia.- 3.1.8. Ecology of Plague.- 3.1.9. Mortality from Plague.- 3.2. Yersinia enterocolitica Infection.- 3.2.1. Geographic Distribution.- 3.2.2. Serotypes and Biotypes.- 3.2.3. Reservoirs and Environmental Sources.- 3.2.4. Epidemics.- 3.2.5. Seasonal Variation in Occurrence.- 3.2.6. Effects of Age and Sex.- 3.2.7. Other Host Factors.- 3.2.8. Relationship to Other Infections.- 3.3. Yersinia pseudotuberculosis Infection.- References.- 4. Clinical Syndromes and Pathology in Humans.- 4.1. Plague.- 4.1.1. Bubonic Plague.- 4.1.2. Cutaneous Manifestations.- 4.1.3. Septicemic Plague.- 4.1.4. Pneumonic Plague.- 4.1.5. Meningeal Plague.- 4.1.6. Plague Pharyngitis.- 4.1.7. Liver and Spleen Involvement.- 4.1.8. Kidney Involvement.- 4.1.9. Cardiac Involvement.- 4.1.10. Hematological Aspects.- 4.1.11. Plague-Simulating Surgical Emergencies.- 4.1.12. Differential Diagnosis.- 4.1.13. Mortality.- 4.2. Yersinia enterocolitica Infection.- 4.2.1. Acute Enteritis.- 4.2.2. Abdominal Pain and Appendicitislike Syndrome.- 4.2.3. Arthritis.- 4.2.4. Erythema Nodosum.- 4.2.5. Septicemia and Generalized Infections.- 4.2.6. Miscellaneous Clinical Forms.- 4.3. Yersinia pseudotuberculosis Infection.- Referencl“"