Why was disease a problem for many Native Americans, but not for Europeans in the New World?

In many cases, the arrival of Europeans brought chaos to Native societies, causing them to miss a corn planting or fall hunt, which could leave them vulnerable to disease. ... At Jamestown, 80 percent of colonists died between 1607 and 1625 as malnutrition and other difficulties left them vulnerable to illness

Explanation:

b toward the volcano.landward. the landward side of something is the side nearest to the land or facing the land, rather than the sea.

troy donahue,   i think.