Participation on a crusade to the eastern Mediterranean or the Baltic region would have exposed individuals from Europe to a range of diseases at a time when the stress of such an expedition should have weakened their resistance.
By comparing mortality in clergy and knights, study of the Fifth Crusade (1217-1221) has suggested that about 19 percent of the wealthier participants died from malnutrition and infectious disease [James M. Powell, Anatomy of a Crusade, 1213-1221 (Philadelphia: University of Pennsylvania Press, 1986), pp. 169-171]. We might expect the poor to have even higher mortality, since they had little money to pay for medical care when sick or food at times of shortage. There are many examples in the chronicles when large numbers died from starvation, and specific nutritional deficiency syndromes, such as scurvy (vitamin C deficiency) and night blindness (vitamin A deficiency), also occurred. The concentration of large numbers of people in land armies and ships should have encouraged the transmission of infectious diseases. Epidemics frequently took their toll on armies, but often insufficient details of the symptoms were recorded in the chronicles for a modern identification of the cause to be made. Those army camps close to marshes would have been susceptible to mosquito-borne diseases such as malaria, while poor sanitary arrangements would have led to waterborne infections such as dysentery.
Roundworm eggs on the head of a pin. (Clouds Hill Imaging Ltd./Corbis)
In more stable times, the Frankish settlers of Outremer experienced those infectious diseases endemic to the region. Leprosy was one of the most feared diseases in the medieval period. It may cause skin ulceration, blindness, destruction of the nose, and deformities of the hands and feet. However, the fear was due not only to the physical disfigurement it can cause, but also to the moral and social implications of diagnosis. Many in Europe believed the disease was a punishment for sin, and the sick were often obliged to live separately, typically in foundations known as leprosaria. The military Order of St. Lazarus was formed to accommodate soldiers with the disease in the Frankish kingdoms. The best-known Frank with leprosy was Baldwin IV, king of Jerusalem (1174-1185). Parasitic intestinal worms were common in the medieval world, and the Frankish states were no exception. Excavation of the latrines of the Hospital of St. John in Acre (mod. ‘Akko, Israel) has shown that members of the order were infested with roundworm, whipworm, and the fish tapeworm. Dental disease was a further condition widespread in the Frankish population. Excavated human remains frequently demonstrate both dental caries and heavy tooth wear. Often these problems were so severe that many of the teeth were lost before death. It is possible that dietary influences were responsible, and the consumption of sweet, sticky foods such as sugarcane, figs, and dates cultivated in the Levant would be expected to encourage dental caries.
St. Benedict healing a leper, Rome, eleventh century. (Scala/Art Resource)
It is also important to understand contrasts in health at a population level. The excavated remains of children who died at the crusader-period farming village of Parvum Ger- inum (mod. Jezreel, Israel) and the Frankish castle of Vallis Moysis (mod. al Wu‘ayra, Jordan) suggest that health in the children was much better in the village than at the castle. Children at the castle were dying very young, and some even suffered from scurvy. Relying on stored foods rather than fresh produce was a major cause of the poor health there, but the crowded conditions and limited sanitation facilities in castles may have contributed to the problem.
The crusades are often blamed for spreading disease in the medieval period. However, most of the diseases described here were already endemic in Europe and the Near and Middle East by that time, and so the disease epidemiology of the region is unlikely to have been significantly affected. It is quite possible, however, that particular epidemics could have been transported by those traveling between Europe and Outremer.