"It's the soroche, the mountain-sickness," explained Professor Ditson.
The severity of mountain-sickness differs greatly in different localities, apparently not depending entirely on the altitude.
And how will I manage to tow along this lump of a Pinocchio who is half dead with mountain-sickness?
mountain sickness moun·tain sickness (moun'tən)
Altitude sickness brought on by the diminished oxygen pressure at mountain elevations.