The Measles Epidemic of 1530-1531 affected the populations of Mexico and Peru in a variety of ways. The epidemic impacted the physical populations of the natives, the religions practiced in the areas they inhabited, and also the social systems of the natives.

The measles virus brought from the Old World by Spanish conquistadors ravaged the physical populations of the natives who inhabited the areas of Mexico and Peru (McGrew, 1985). The Measles Epidemic of 1530-1531 followed the Smallpox Epidemic of 1520 where one-third of the Aztec empire (its original population ranging between 20 and 30 million), located in Mexico, succumbed to disease. Many more were killed as the smallpox virus spread through South America. Although the Measles Epidemic of 1530-1531 did not possess as high as a mortality rate of the Smallpox Epidemic of 1520, deaths were still frequent The frequent deaths, as with the Smallpox Epidemic, can be attributed to the isolation of the natives and their resulting non-immunity to the measles virus, something they had never encountered before. Because of the Measles Epidemic along with other epidemics, the conquistadors who numbered only in the hundreds conquered large and once glorious empires, such as the Aztecs (McNeill, 1976).

The Measles Epidemic greatly changed the religions followed by the native populations who lived in present-day Mexico and Peru. As it spread through Spanish-claimed South America, the measles virus wreaked havoc on the natives who were isolated and had no contact with the disease (McGrew, 1985). Because the natives lacked any type of experience with epidemics, they immediately thought that this plague had a supernatural cause, the manifestation of Gods’ displeasure. At the same time, however, the natives observed that most of the Spaniards seemed unable to contract the illness. Science now explains that the Spaniards’ immunity to measles can be attributed to the fact that the Spaniards had constant exposure to the disease during childhood. The Spaniards’ immunity and subsequent defeat and conquest of the natives because of the natives’ dwindling numbers led them to believe that the Gods favored the white man and also contributed to the natives’ growing disbelief in their Gods (McNeill, 1976). This situation is linked “to the ease with which Christianity spread in much of the New World” (Fagg, 1963, p. 244). Christian missionaries led mass conversions and a dramatic change from pagan religions to Christianity followed the Measles Epidemic of 1530-1531 (McNeill, 1976).

As the Aztecan population diminished as a result of the Measles epidemic, the social systems were deeply affected. At one time, the Aztec civilization, due to its military and economic power, extended from the Pacific Ocean to the Gulf Coast in the east (McNeill, 1976). However, the power of the Aztecs was no longer so great as a result of less military power accompanying the deaths of many warriors. These Aztecan warriors had an important part in the social hierarchy of the Aztecan Empire; they were below the nobles who formed the upper class and formed part of the middle class (“The Aztec…”, n.d.). Different parts of the Aztecan social life were also affected by Measles Epidemic. A strong piece of evidence of a modification of a cultural trait was the desisting of bathing in 1531 in “direct response to contagion and Spanish example” (Dobyns, 1997). By not participating in communal bathing, the Aztecs could escape infection in a more effective way. The arrival of Spaniards and the outbreak of measles among the native populations inspired the natives’ new feelings toward the Spaniards. The Spanish appeared invincible because as more and more Aztecan people would get infected, the Spanish would be spared. The Aztecs felt that the white men from Spain were superior and almost like gods, so they were very fearful of them. This fear and the supposed superiority of the Spanish affected them greatly by causing them to not want to oppose the Spanish as much, and so the Spanish were able to turn them into slaves for their mining work. Of these three huge effects on the population caused by the Measles Epidemic, the greatest one was that of the decline of the physical populations, which the Aztec would never recover from.

The Columbian Exchange, which was the massive influx of trade and colonization resulting from the discovery of the Americas by Christopher Columbus, brought many new products to the Americas. These included, but are by no means limited to, cattle, horses, wheat, citrus, bananas, and many other crops. In addition, the Europeans discovered many new crops like potatoes, sweet potatoes, carrots, tobbaco, and corn. The European expansion also brought diseases like measles, smallpox and bubonic plague to which the Europeans had developed an immunity because of continued exposure in their homeland, but to which the natives were entirely unprepared. The Europeans used their superior technology to dominate and enslave the natives and force them to do hard labor. When the supply of native indigenous people ran out, the Europeans began to import slaves from the coast of Africa, which contributed to the strong African influence in the cultures of some areas of our region (namely the Caribbean).
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In 1519, Hernando Cortes arrived on the coast of Mexico in present-day Veracruz, with every intention of conquering the Aztec population and claiming this southern territory in the name of Spain. Over 600 men accompanied Cortes on his voyage, and the ships that Cortes and his crew arrived in displayed some of the finest weaponry of the time. However, the most deadly threat to the Aztec population took the form of a very different kind of visitor. Unlike the gargantuan ships on which the formidable conquistadors arrived, this visitor could not be seen with the naked eye. In fact, this visitor was part of a separate expedition—one led by a lesser known explorer named Panfilo de Narvaez. Narvaez’s expedition is often glossed over in history books, but the impact Narvaez’s expedition had on the Aztec empire strongly resonated throughout all the civilizations of South America (Giblin, 1995).

Before Narvaez’s crew arrived in Mexico, Cortes and his men had already defeated the emperor of the Aztecs, Moctezuma II. On November 8, 1519, the first attack on the Aztecs took place in the capital of the empire, Tenochtitlan. The attack was facilitated by Moctezuma’s initial acceptance of the conquistadors, due to his belief that Cortes might be a reincarnation of the god Quetzalcoatl. Moctezuma’s assumption led the Aztecs to welcome the conquistadors into the city with great pomp and revelry (Bulliet, 1997). Despite this magnanimous welcome, Cortes and his men proceeded to violently attack the Aztecs, who were ill-equipped against the conquistadors’ newfangled weaponry (Marks, 1993). Cortes subsequently became the new ruler of Tenochtitlan (Bulliet, 1997).

Six months later, Narvaez’s expedition arrived from Cuba at Veracruz to arrest Cortes’ men. When word of Narvaez’s expedition reached Cortes, he left eighty of his men at Tenochtitlan while the rest accompanied him to Veracruz to fight Narvaez’s crew. After Cortes’ crew easily claimed victory, Narvaez and his crew were assimilated into Cortes’ original crew. The new combined crew returned to Tenochtitlan under the leadership of Cortes. However, Narvaez’s crew included a certain slave from Africa. This slave is suspected to be the original carrier of the aforementioned deadly visitor: the smallpox virus.

The virus was allegedly transmitted from the slave to Cortes’ men, who transmitted the virus to the Aztecs upon returning to Tenochtitlan. The Aztecs had not had exposure to a wide variety of viral diseases, partly because of Mexico’s geological isolation from the rest of the world. The Aztecs also had weaker immune systems due to a lack of exposure to certain livestock that the Spaniards had already encountered. However, the bathing routine of the Aztecs was one of the key factors that led to the rapid transmittance of viral disease. The Aztecs treated diseases by frequently engaging in communal baths, and the bathwater from consecutive baths would be re-used. Any viral genetic material from an infected individual’s open pustule could leak into the water and proceed to infect multiple subsequent bathers (Marks, 1993). The smallpox disease is believed to have killed 25-50% of those infected (Coryell, 1997). The disease continued to ravage the territory of Mexico, spreading to both the Inca and Maya empires and eventually reaching Brazil. The mortalities from smallpox largely contributed to the success of the Spanish conquest in Mexico. In an account of the conquest written by Bernardino de Sahagun entitled General History of the Things of New Spain, Sahagun alludes to the smallpox disease several times. He describes the impacts of the virus, saying “The pustules that covered people caused great desolation; very many people died of them, and many just starved to death; starvation reigned, and no one took care of others any longer (Woy, 2001).”

The exact origin of the 1521 smallpox epidemic is difficult to pinpoint. According to medical historians, the smallpox disease has existed for 10,000 years, and the roots of the virus can be traced back to primate ancestors (Masci, 2003). Medical historians believe that the disease may have originated at the time when human beings first began to aggregate into discrete communities and travel, allowing the disease to spread and radiate throughout various early communities. Some historians hypothesize that the disease may have first originated in Mesopotamia and spread to the adjacent countries, including Egypt (Geddes, 2006). As researchers, we believe that this explanation could be extended to include the further spread of the virus from Egypt to Africa, a continent that is in close proximity to Egypt. Such a hypothesis would fit well with the events that transpired in the 1521 epidemic, explaining why an African slave would have been the first carrier of the disease. At the time of the outbreak, no known explanation for the event existed. The people of the time were not aware of the concept of microorganisms, so these people most likely suspected a religious correlation. With new technology and knowledge about viral evolution, modern scientists have a far more comprehensive understanding of the molecular mechanisms of viral epidemics, which highlights the crucial difference between current and ancient explanations of the event.