Disease is a two-edged sword

From Carnage and Culture by Victor Davis Hanson. Page 214.

The disease argument cuts both ways: there was a variety of tropical illnesses with which the Europeans had almost no experience or immunity against. Most contemporary accounts mention constant bronchial ailments and fevers that severely weakened and sometimes killed Cortés’s soldiers. New World malarias and dysenteries were far more virulent than similar outbreaks in Spain. Some also suffered from syphilis-like cankers, an especially unpleasant experience for armored men in the tropics. Moreover, not all of Cortés’s men had been exposed to smallpox and gained immunity against a disease that still wiped out thousands in the major urban areas of Europe. Given the small numbers in his army, even a few dozen Spaniards with the disease could have had as great an effect on the relative military efficacy of the conquistadors as did the thousands of infected natives in an Aztec empire of more than a million. In Cortés’s own letters and the annals of contemporary Spanish observers, smallpox, though mentioned, is never characterized as a predominant factor on either side of the struggle. This was because the Castilians, themselves beset by a host of diseases and unable to detect any sudden weakness in the resistance of Tenochtitlán, never fully appreciated the degree to which the outbreak had become pandemic among their enemies.

What prevented the Europeans from being wiped out by these new fevers and old illnesses is explained as much by demographics and culture as by biological causes. As a largely heterogeneous group of younger male warriors with varying backgrounds and travel experience, the Castilians were rarely cooped up in small urban quarters in constant contact with women, children, and the aged. They also had almost no responsibility or need to care for the civilian infected. Besides some biological immunity to smallpox, there was among the Spanish arrivals a long empirical tradition of combating disease outbreaks—Seville would lose half its population to plague in 1600, yet recover without being destroyed by either the disease or opportunistic foreign invasion.

Throughout the fighting, the conquistadors applied wool and cotton bandages to wounds, and found, in a gruesome manner, that the fat from freshly slain Indians worked as an excellent salve and healing cream. While scientific knowledge of viruses and bacilli was, of course, absent in sixteenth-century Europe, and indeed the entire mechanism of infectious agents unknown, the Spaniards did draw on a long empirical tradition that went back to classical medical writers like Hippocrates and Galen, who drew on firsthand observations of epidemics in Greek and Italian cities and had thus helped establish Western traditions emphasizing the importance of proper quarantine, medicinal diets, sleep, and the careful burning of the dead.

As a consequence of that long legacy, the Spaniards realized that close contact with the ill spread infection, that the dead had to be immediately disposed of, that the course of diseases was predictable by acute observation of symptoms, and that the process of empirical observation, diagnosis, and prognosis was superior to mere incantation and sacrifice. Catholic priests may have argued that one became ill as God’s punishment for prior sins and offered prayer as healing, but most Spaniards realized that once the infection set in, there was a predictable course of illness to follow, one that to some degree could be ameliorated by medicines, careful nursing, diet, and isolation.

In contrast, the native people of Mexico, like the ancient Egyptians and many Catholic priests, believed that internal diseases were a result of gods or evil adversaries, who wished to punish or take possession of the afflicted—and could thus be thwarted by charms and incantations. Aztec fortune-tellers consulted the pattern of beans thrown on cotton fabrics to determine the etiology of the disease. Various sacrifices, human and animal, would surely appease the angry Macuilxochitl or Tezcatlipoca—or was it Xipa? The idea that communal sleeping and bathing, group sweat-houses, eating on the floor, wearing of human skin, cannibalism, or the lack of immediate burial and disposal of the dead had anything to do with the spread of diseases was poorly known even among the Mesoamerican herbalists.