Diseases among the Tsalal

One thing I've been thinking about recently, in regards to TTL, is with their pervasive cannibalism, the odds of a prion disease similar to Kuru developing seems rather high. Hell, given the incubation time with these diseases measures in the years, it's highly likely the disease will spread quite far before anything is done - particularly in cultures which eat those who die of "natural causes" in addition to butchering.

Hell, the deaths could rise to the millions, which would probably be enough to stop cannibalism entirely, as nations which didn't engaged in little to no cannibalism, like the Yag, wouldn't see any population crash, and thus would become the premier nation states on the continent.

But to keep your TL going, you'd need to have one of two things happen.

1. A plague burns its way through the whole continent, to the point where the survivors are all plague resistant. Something would need to happen to the Yag though to counterbalance this - perhaps the other nations blame them due to their low infection rate, similar to how Jews were often blamed during the Black Plague?

2. A taboo against eating human brains develops. Although it's still debated if eating brains actually caused Kuru, or the butchering process, which allowed prions to get into cuts on the skin of "preparers." So maybe more complicated taboos would have to form, with a "caste" who were themselves taboo to eat preparing corpses for consumption.

PRION DISEASES
Prion diseases do occur among various Tsalal societies, and are known, but have never become a major epidemic problem. In part, this is due to socialization of cannibalism.

In the Early Human Era, cannibalism was practiced by the whole community on its weakest members, or by the strongest members upon the weakest. During these phases, there was not a lot of discrimination going on, and sick or diseased individuals, including those suffering from prion diseases, were killed and consumed readily.

The results were prion outbreaks, and other disease epidemics occurring frequently within communities. On the other hand, populations were thin, population crashes were frequent, and mortality within a community tended to be high.

As previously noted, often successful reproduction fell below replacement rates and the Tsalal, often in different areas, and sometimes as a whole flirted with extinction from time to time.

One result was that the survivors had a fairly robust immune system, and a generally high degree of resistance to prion disease.

As cannibalism evolved from a famine subsistence to a social dominance trait, a number of factors worked together to limit the incidence and outbreak of prion disease.

One of which was the increasing selectivity of victims - obviously sick or dysfunctioning individuals were discarded. This did not stop prion disease because of lengthy incubation periods, but it did tend to slightly reduce the pool of infected.

A more significant factor was the reduction in commensual cannibalism. The class of the eaten and the class of the eaters became more distinct, reducing the odds that a person who became infected with prion disease would become a vector for infection through being eaten themselves. This social disconnect greatly reduced incidence of prion transmission.

Another feature was greater care in selecting and eating. Brains and saturated tissues were often not consumed, though of course, practices differed from place to place.

Finally, the level of resistance through natural selection increased and remained high. In normal human populations, incubation periods ranged between 5 and 20 years. Among the Tsalal incubation periods are seldom less than 15 and often as high as 40 or 50 years. For most of their history, the Tsalal lifespan averaged between 35 and 45, so prion diseases tended not to be a major killer.

Nevertheless, despite marked reductions in risk and transmission factors prion disease did make occasional appearances in Tsalal society, where it appears to have contributed to bouts of madness and mania among elites and where its late stages were known as the "Chief's Sickness", given its tendency to be restricted to higher status individuals.

DISEASE IN TSALAL HISTORY
The epidemiological picture of the Tsalal changed in the Middle Human Era, and even more in the Later Human Era, with the commencement of large scale agriculture. Humans came into close, even intimate (shudder) contact with a number of domesticated animals - including primate species (various forms of hive monkey), avians (penguins, including consuming regurgitated stomach content), edentates (Shaghut and Shaghui, sloths), marsupials (hoppers and devils), mothbeasts, and even invertebrates (glow worms, termites, meat worms).

The result was a number of cross species diseases, infections and parasites, particularly from the other primates. Avians contributed diseases, but due to difference circumstances, the exchange was generally one way. Sloths also traded illness back and forth. Transmission events were erratic. Initial infections were often virulent and spread rapidly, but would generally burn out over the winter season as human populations ceased to move about.

Mortality from disease survivors would often experience a second spike during the winter as food and fuel scarcity took their toll on weakened individuals.

Outbreaks of cross species diseases often resulted in wild population fluctuations within a region. The indigenous population would collapse, leaving vacant territory which would be reoccupied slowly or quickly depending on the neighboring population. If slowly, follow up outbreaks would often be delayed or avoided. If quickly, the invading populations would fall ill, die, and be replaced by more invaders falling ill and dying, until there was a residue of survivors who were relatively hardy.

The effects of crossover outbreaks into animal populations were less predictable. It appears that the domestication of mothbeasts began in a region where a crossover disease literally eliminated sloth species altogether, and there was a demand or need for draft domestic animal labour. Shaghui in particular seemed susceptible to crossover epidemics.

Another factor contributing to the development and spread of diseases was the tendency of Tsalal to live in close communal groups, particularly in the winter. In the early human era, this wasn't a major factor as most of the population was highly dispersed and communal groups tended to be families or small bands.

With the advent of the Middle Human Era, winter population sizes and densities tended to increase dramatically. This was also the age when humans lived communally and in close proximity with primates and edentates, and the rise of crossover diseases.

However, the main explosions of density related illnesses - transmission through body fluids, sexual contact, shared water, air, etc. began in the Later Human Era as large populations began to concentrate. This was particularly in the Sunken Cities of the middle coal age and beyond. The Coal Era was also the first age of regular significant social contact through trade and commerce, as in the Coal Kingdoms, or Empire or War as in the Ptarh and Zhudan.

So it was only in the later human era that we began to see massive pandemics and plagues, which materially affected the course of human culture and occasionally caused massive population drops.

PS: Thanks for bringing it up. I've actually thought about Kuru and Prions from time to time. It's inevitable on the subject of cannibalism. And issues of human/animal disease exchange, population densities and disease vectors are significant... but not very exciting in some ways. So it's nice to actually have a reason to talk about it.