During the Middle Ages (roughly A.D. 500-1500), Europe changed from an agrarian society composed of relatively small and isolated communities to an increasingly commercial and urban world, though still predominantly agricultural.
After centuries of static or declining growth in late antiquity, the population of Europe increased approximately threefold between 800 and 1300. Generally, the history of medieval diseases reflects these demographic and economic facts.
While the ancient diseases of pneumonia, tuberculosis, and smallpox, and others including typhoid, diphtheria, cholera, malaria, typhus, anthrax, scarlet fever, measles, epilepsy, trachoma, gonorrehea, and amebiasis persisted throughout our period, many diseases of Europeans during the early Middle Ages were related to deficient diet.Improved nutrition in the later Middle Ages led to a relatively larger population. As Fernand Braudel (1979) has emphasized, an increase in population alters all aspects of life, bringing advantages but at the same time threatening the existing standard of living and hope of improving that standard. In addition, it can bring disease. Ironically, the improved nutrition that made possible the growth of population, towns, and trade in the Middle Ages in turn created fertile opportunities for the contagious diseases that ultimately changed the face of Europe.