50%+ death rate for combined epidemics is no fun, but, yes, they were 'fortunate' (as you say, to the extent such a word can be used in such a situation), as Native Americans sometimes had 90% die offs with repeated waves of various diseases iOTL. iTTL, the latter will be even worse off, as they have the 3rd World diseases to cope with as well as Eurasian ones.
Yes, there is a certain morbid irony in being able to call the eventual 50+% death rate as "lucky". Only when compared to their relatives in OTL, of course, but still...
For clarity (since I realised I may not have been completely clear), 50+% of the pre-contact population will be the eventual death toll of all the combined epidemics. It's not quite there yet. The total epidemics before the Great Death (chickenpox, mumps etc) killed 25% of the pre-contact population. There was a little population growth in between (a decade or more's worth, depending on region), and then the Great Death killed 25-30% of the lower population. In terms of the pre-contact population, the net effect is approximately 45% loss.
Of course, there's still influenza (over most of the continent), smallpox, typhoid, and a cluster of "lesser" illnesses like diphtheria, pertussis (whooping cough), etc which have not even hit yet. The total death toll is going to be even higher. Perhaps 65-70% of precontact population, depending on society.
And despite all of that, as you say, they're still better off than the Native Americans, who were hit worse in OTL and will be hit even harder ITTL. Plus a few other groups such as Pacific Islanders who will also be hit even worse.
Stupid disease, always ruining everything.
It's a tragedy, but not one which is realistically avoidable in this or any timeline dealing with contact between the Old World and societies without those diseases. Unless contact could be held off until the invention of mass vaccination (pretty much an ASB enterprise), the consequences are always going to be horrific.
I think I've gone about as far as I plausibly can in making the epidemics slightly less severe.
Excellent, if harrowing, stuff, Jared. I was wondering when we'd see Ashkettle and Clements again.
It was tough but necessary to write.
Ashkettle and Clements were always going to reemerge around now, when the Great Death hit. They will probably pop up in a variety of other places, depending on what I find useful to frame things, but the two next places where I have definite plans for their appearance (including bits sketched out) are the Hunter's crusades, and then later the Aururian front during the Nine Years' War (1740s/1750s, approximately).
Isn't that level of die back pretty much going to shatter any society?
Place under severe strain and lead to local depopulation, certainly. Not necessarily collapse entirely. Some almost certainly will; others will probably hold on, at least from internal pressures.
The individual death toll from any particular plague is about the same as that of the Antonine Plagues in the Roman Empire. That caused all sorts of problems, of course, but didn't lead to the shattering of the Roman Empire.
The cumulative death toll is roughly on par with the Black Death in Europe. While that led to local depopulation (villages being abandoned, etc), widespread persecutions of minorities (such as Jews), increase in violence, etc, it didn't lead to wholescale social collapse. In places like Italy, the death toll was probably even higher (60-80% in the cities, probably less in the countryside), and again it didn't create complete social collapse. The Black Death didn't even do more than cause a slight lull in the Hundred Years' War; England was back to invading France within half a decade of the peak of the Black Death there.
The big problems are two-fold: they're taking this level of depopulation while being an increasingly desired target for European colonialism; and the plagues are a long way from finished yet. This was the individual worst plague overall, but there's sitll more to come.
I did a quick google, and it looks like rabbinical usage is to require a 'tradition' of birds being kosher before they can they can be considered kosher, or that they be the same as something already kosher. So, no Emu won't be kosher. Unfortunately.
So how the blip did turkey end up Kosher?
I understand that the turkey is not universally considered kosher, although many authorities do permit it. Going from very limited memory, I think I heard that the turkey was considered like enough to a guineafowl to be considered kosher.
So all TTL needs is for someone to decide that emu is just a very very big guineafowl, and we're good to go.