Few comments on diseases:
1) The old world diseases are generally a result of animal domesication and the proximity in which humans lived with animals.
2) If the old world disease package was brought over early, it wouldn't grant them any immunity unless the disease itself stuck around, which is only possible if the populations were higher. Which is perfectly possible in itself. But they're gonna have to deal with the crowd diseases for awhile to get any immunity.
1) The old world diseases are generally a result of animal domesication and the proximity in which humans lived with animals.
2) If the old world disease package was brought over early, it wouldn't grant them any immunity unless the disease itself stuck around, which is only possible if the populations were higher. Which is perfectly possible in itself. But they're gonna have to deal with the crowd diseases for awhile to get any immunity.