I remember from Stephen Ambrose's book "Undaunted Courage" that oftentimes they kept concubine Native American Indians as "guides" / interpretors, who sometimes

I remember from Stephen Ambrose's book "Undaunted Courage" that oftentimes they kept concubine Native American Indians as "guides" / interpretors, who sometimes ended up becoming the group's traveling STD incubator. Another 90's book mentioning the prevalence of Syphilis pre-1492 is "Guns, Germs, Steel" [which is about 200 pages longer than it needs to be, but still a worthwhile read].