A hanta virus plague was well underway in the Americas when the first Conquistidores visited Peru. They wrote about it. Many of them also died from it. There was a later plague on the US East Coast that had a 95% death rate in the winter of 1646/47 ~ and again in 1647/48. White folks gained the upper hand in the territory after that one simply because they could import more white folks. The Indians were eventually reduced to becoming game hunters in the new economy.
The Justinian thing has always been dismissed as the cause of the destruction of Western and Northern Europe ~ but yet if that plague also arrived on the heels of a wet spell after a lengthy drought, quite possibly we should blame the drought and its cause. That's the event(s) of 535 AD ~ which may have involved a large comet or asteroid passing close to Earth, or a gigantic volcano eruption, or both, or a bunch of 'em!
If the black death was let loose in Europe then the death rate was probably as high as we can imagine.
Cystic Fibrosis researchers have identified more than 1,000 different CF gene mutations ~ 1,000! If we have but one such mutation each time whatever it is CF protects us against, that means that cause keeps coming back and attacking Europeans! (and perhaps others ~ estimates for CF in India are roughly the same)
The CF theory is that the CF mutation(s) protect people from the black death in the same way Sickle Cell disease protects subsaharan Africans from malaria!
It's an autosomal recessive, so you have to have two copies of a mutated CF gene to develop the symptoms. If you have only one copy, you are safe from black death. If you have no copies you are not safe from black death.
The current theory is that when the black death hit Europe in the Middle Ages the death rate was 100% among people without a mutated CF gene! They all died. The plague didn't mutate since it was the same old plague that'd swept through Europe ~ literally a rat infested Europe ~ time after time for thousands of years. The observation of different death rates merely marked the difference in time since the last plague swept through an area. The further North you'd go, the more people had the mutated CF genes from more recent plagues, so they'd have a lower death rate. In the South where people had a longer time span between plagues, fewer had the mutated CF gene so more of them died.
You can also see an incentive for the Mongols to give up herding animals on the vast grasslands of Mongolia and relocate to far more healthy China! They would have done that hundreds of times before. BTW, the North/South migrations of the Turcic speaking people of the Steppes would also be coordinated in time with the Great Droughts, not just the arrival of the plague. Drought arrives; animals starve; people go South.
The black death is also present in the Americas but historical records suggest that hanta is the greater threat here.
Fortunately for all of us the human reproductive rate is sufficient to keep our numbers up ahead of the worst the plagues can do to us.
“Fortunately for all of us the human reproductive rate is sufficient to keep our numbers up ahead of the worst the plagues can do to us.”
That and disease plagues that kill their hosts quickly tend to burn out faster than diseases that incubate more slowly and thus have more time to spread from host to host. Ebola outbreaks, for example, are generally short-lived.
interesting accounts.
Please tell me we have the pharmacological armory in case of another onslaught of Y. pestis.