It was the incarnation of blind insensenate Greed. It was a monster devouring with a thousand mouths, trampling with a thousand hoofs: it was the Great Butcher — it was the spirit of Capitalism made flesh.- Upton Sinclair, The Jungle 1906 [1]
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Red River Station. The primary departure point for Texas Longhorns on to the Chisholm Trail. An abrupt bend in the River checked its flow here, and had been used by Indians and cattle-men for generations. But now, with the boom in demand for beef, cattle crowded this bend. It was said a nimble enough cowboy could walk across the river on their backs. And maybe it was true.
Was it here that it first happened? That some Texas Longhorn, smelling of rotting meat, fell into the Red River, the first victim of that scourge which would come to be known for this River? Probably not....
But history would record it as the Red River Shakes nonetheless.
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The Red River Shakes is a transmissible spongiform encephalopathy, occurring in cattle, which causes degeneration of the brain tissue and spinal cord. The causative agent is a deformed protein known as a prion which can spread to the central nervous system and peripheral nervous system of affected cattle, infecting the meat and muscle. It has a long incubation period, up to four years, although peripheral symptoms may be noticed before that time. In its final stages is a fatal degenerative disorder, which results in rapid weight loss, a loss of motor functions and the onset of necrosis in fatty tissue.
The primary nature of animal-to-animal transmission is through the consumption of grass infected by the droppings of affected cattle. The prions which cause the disease can survive in the soil, even in harsh conditions, and can go on to affect any of the cattle which feed on grass in the area.
Identifying the origins of the Red River Shakes is difficult. Early reports conflated the disease with the other lesser diseases found among Texas longhorns. [2] The first noticeable outbreak of the Red River Shakes was in 1880, although the spread of the disease afterwards and the long incubation period indicates that it had existed before then.[3]
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[1] This is an external OTL quote. Due to the circumstances of TTL, it is likely never written.
[2] Despite being known as the defining breed of the American West, Texas Longhorns were identified by more easterly cattle-herders as "disease-ridden" and Missouri passed a quarantine law for that purpose. Their free-ranging did often give them a number of disorders ranging from digestion to parasites and so on.
[3] This disease is based on Chronic Wasting Disease and mad Cow Disease, obviously, and the allohistorical observer would see that it originates sometime in 1874, just as the cattle boom is picking up. ITL observers don't see that, of course.