Even if we can, i'm rather wary of that... If things are similar to the real world, we'd get to be responsible for super plagues destroying entire civs, which sounds like the kind of thing our civ would respond...poorly to, assuming we keep our general values that long (among other things, the possibility of managed ecosystems collapse occurring due to us spreading plague for once instead of spreading the solution, and our solutions being too late or not strong enough to save the natives, would probably lead to "must take actions to save as many people and systems as possible")
That said, i don't think AN would stick to the real world version of things. I personally am guessing that the Not!Americas have more surviving domesticatable animals than just the llama, and will have more advanced polities with enough large cities with close animals to have spawned plagues of their own, leading to a less total destruction during contact...and having similar effects on us or whichever civ makes contact, from their unique plagues that we're not used to.