Fire-head Fever was a disease found on the Southern Continent.
The cause of Fire-head Fever is unknown, but the disease is known to exist only in those who travel to the Southern Continent. Because the Southern Continent was unexplored for most of Pern's recorded history, the disease was largely unknown when exploration resumed in the Ninth Pass. The onset of Fire-head Fever is marked by cold-like symptoms, and is often mistaken for a mere cold. As the disease progresses, suffers become afflicted by a high fever, severe headaches, and hallucinations which take the form of spots. The disease can be very severe and can cause death, even in otherwise healthy individuals.
After the fever breaks, Fire-head suffers will retain a sensitivity to light and continue to have headaches. If care is not taken during this time period, permanent damage to the eyes can result. Recovery is assumed once both symptoms subside. However, the disease will leave the sufferer weakened for some time. In addition, it is considered dangerous to go between for a lengthy period of time following Fire-head. This danger was unknown following the disease's discovery, but was revealed when a dragonrider went between too soon after recovering. He would go blind, then was driven mad by severe head pain before dying. If a person pushes themselves too soon after recovery, a relapse can take place, marked by hallucinatory spots and headaches.
Treatment for Fire-head primarily involves dealing with the high fever. The visual symptoms are reduced by covering the sufferer's eyes. The patient is encouraged to keep their head still to reduce pain. As recovery begins, a sufferer may be given fellis to promote sleep. Recovery is usually slow, to prevent relapse. A restriction on going between is put in place and enforced, due to the danger of death.