According to the textbook, why did diseases such as smallpox and measles produce epidemics that ravaged or completely wiped out native populations in the Americas after contact with Europeans in the late fifteenth century?

The native Americans lacked the immune system to fight diseases like measles and smallpox

Explanation:

The 15th century brought many diseases with the arrival of Europeans in Native America. These diseases have taken on the form of epidemics and have virtually wiped out the population of Native Americans. This is because Americans have no prior exposure to European culture and lifestyle, so they have not developed the immunity needed internally to fight diseases like measles, smallpox, and cholera. They do not even have drugs to prevent or fight these diseases.