Energy, which causes the built up pressure. :)
Answer: Because they had never developed immunities to the disease
Anti semitism describes mistreatment of news
In general terms one can think of expansionism, that is occupying land that were deamed not productive in order to cultivate or explore -- onje can check the American expansion to the West, this shows that the settlers had little to no regard to the first settlers.
After the consolidation of the American territory, latinos and native Americans were relegaded as second class citizens, along with ex-slaves, most lations and Afroamericans occupied big centers but mostly in the outskirts, and Native Americans now are over 5 million people, a few more than a half this number live in Alaska alone.
Nowadays there is the problem with the border with Mexico and one can say that there is justified fear of human traficking and smuggling with immigrants who seek a better life in the US, the problem is, there are good people who want to work and prosper in the US but they are blended together with evil-doers, still showing a general suspicion to Latinos as a group.