I can fly!
What exactly causes the illness is not entirely understood, but there is a correlation with living on high hills and mountains and an increased risk of getting it.
It always starts with the person becoming fascinated with birds and/or flight in general, with it turning to a vision that Venirans will be ably to fly until the person has an 'epiphany', causing the ill to believe that they can fly, which is the final symptom.
The primary effects are not harmful, but due to the desire to jump off high places in order to prove that they can fly secondary injuries leading to death are not uncommon, especially in mountainous regions.
The symptoms go away after a few months on their own accord, but in the meantime the sick must be kept away from high places so they cannot jump off it and potentially injure themselves.
Since there are no physical symptoms the ill must rely on people around them to spot and report signs of the illness progressing, which can be a problem for those who are naturally interested in birds or flight.
The only known way to reduce the risk of getting the illness to stay away from the mountainous regions of the world.
For a long time those with this illness were just called crazy with little sense of self preservation, but after a few notable cases this belief wavered.
In order to figure the truth out, people were asked to document cases in order to collect better data. Over the years enough cases were reported reliably that the illness could be properly documented and explained.
Depending on where the illness takes hold reactions vary. In the desert people generally only start suspecting something is wrong when someone starts injuring themselves by jumping off buildings.
In the mountains things are a little different. They have been brought up to look for early signs of the illness and to inform people so treatment can start before they are tempted to jump off a cliff.