Smallpox

Smallpox was introduced in the Americas in 1521, when it first struck the capital of the Aztec empire, Tenochtitlan. Transmitted directly from human-to-human, through contaminated exhaled air, or contact with the open sores or clothing of an infected victim, the disease wiped out entire populations, killing nine in every ten people. Those who cared for the victims of the disease soon developed its symptoms of a fever, severe rash, internal bleeding, and blindness. Since the caretakers of the ill contracted the disease as well, later dying, most natives were doomed to death, if not from the smallpox, from starvation.

Measles

Like smallpox, measles in the New World was linked to the domesticated mammals of the Old World. As the Aztecs and other indigenous people became increasingly exposed to foreign animals, they quickly contracted the highly contagious disease. While the virus, which devastated the Valley of Mexico in 1531-1532, killed many, it covered only a small area of land; this disease was so contained because it could only be spread through contaminated air, exhaled by a sick one.

Malaria

In addition to receiving disease exposure from Europe, the New World also became open to the sicknesses of Africa through the slave trade route. One of them was falciparum malaria, a serious and often fatal strain of the illness. Spread by the mosquito, it caused an infection of the bloodstream, and was then easily transmitted human-to-human by another of the common insects. Just as it did in Africa, the mosquito thrived in the humid, wet jungles of the Central American coast, becoming a serious problem of disease to the native population.

Typhus

Similar to malaria, typhus was also transmitted from an intermediary host to humans. Lice, burrowed in the ships of explorers, thrived on the unsanitary conditions present on the Trans-Atlantic Route. Immediately spilling out onto the shores of Mexico, they passed the bacteria-like microorganisms of typhus from person to person by direct contact. This disease spread quickly among the Indian population, and continues to persist in modern Central and South America and Mexico.

Influenza

Spread from Europe to the Americas in the late fifteenth century, the virus was tied directly to the domesticated animals of the Spanish, foreign to the New World. Influenza first became rooted in Hispaniola with the arrival of Columbus and his men. Linked to their swine and cattle, the highly contagious virus rose to the height of a widespread epidemic soon after, affecting most of the native population.