Here’s a mystery for all the medicos out there, from Isabella Bird’s account of her journeys in Tibet in 1889. This sounds like it might be related to the altitude, but why just this one place? And it sounds as if it is seasonal, suggesting it may be related to the pollen.
“Our party left Leh early on a glorious morning, travelling light, Mr.Redslob, a very learned Lhassa monk, named Gergan, Mr. R.’s servant, my three, and four baggage horses, with two drivers engaged for thejourney. The great Kailas range was to be crossed, and the first day’s march up long, barren, stony valleys, without interest, took us to a piece of level ground, with a small semi-subterranean refuge on which there was barely room for two tents, at the altitude of the summit of Mont Blanc.
For two hours before we reached it the men and animals showed great distress. Gyalpo [the author's horse] stopped every few yards, gasping, with blood trickling from his nostrils, and turned his head so as to look at me, with the question in his eyes, What does this mean? Hassan Khan was reeling from vertigo, but would not give in; the seis, a creature without pluck, was carried in a blanket slung on my tent poles, and even the Tibetans suffered. I felt no inconvenience, but as I unsaddled Gyalpo I was glad that there was no more work to do!
This ‘mountain-sickness,’ called by the natives ladug, or ‘pass-poison,’ is supposed by them to be the result of the odour or pollen of certain plants which grow on the passes. Horses and mules are unable to carry their loads, and men suffer from vertigo, vomiting, violent headache and bleeding from the nose, mouth, and ears, as well as prostration of strength, sometimes complete, and occasionally ending fatally.”