Plague of Fliir

And as the vengeful Fliir cursed her ex-lovers to their breathless end, so too did those afflicted die, drowning in their own beds, their last taste blood. 

Transmission & Vectors

The Plague of Fliir was multimodal - not only could it spread via the air, but due to its magical nature, any connection of magic was a potential avenue of infection. Given the use of magic in the food supply alone, this was catastrophic, spreading the plague through trade without ever having to see an ill person.

Causes

The initial cause of the plague is to this date unknown, although many speculate, due to its long incubation period, a cursed artifact from a careless or unfamiliar adventurer could have been the root. Although unproven, The Circle of Seekers  has taken the brunt of suspicion.
During the first week, transmission was generally limited due to the patient secluding themselves. While a household could possibly pick up the infection from coughing or sneezing, in the initial phase the plague slowly dismantled the victim's internal defenses to prepare for its growth cycle.
During the next phase, the growths begin forming and growing in the lungs and airways. At this point, infection through air becomes much more rapid, as each growth increased the magical pathogen concentration in the breath.
As well, it was found that the pathogenic effects were passed in all manifestations of magic by an infected individual, riding along with the intended effects to be exposed to other creatures.

Symptoms

The Plague of Fliir begins as a particularly irritating cold. After around a week, the symptoms lightened for a period, leaving people feeling recovered. During this period, the immune system is impaired to allow the growth of the wing-like growths in the lungs, 
Roughly a month later, the growths are stimulated and swell, bursting in the lungs and causing a patient without heavy supportive care to pass from either drowning or internal bleeding, depending on the growth distribution in the lungs.

Treatment

When the plague existed, survival outside of constant monitoring by a team of doctors and healers was essentially zero. Under monitoring, doctors could perform manual resuscitation while healers went through the laborious process of healing the internal bleeding.
To the relief of anyone old enough to remember the plague or tales of it, Telkar 's sacrifice seems to have completely annihilated the disease, as well as healed anyone still alive at the time of the ritual.

Prognosis

While the general course of the plague was death, a large portion of the population was either in the asymptomatic phase or in the early stages of the swelling phase, so at the time of Telkar's sacrifice were healed. Studies have shown that these survivors more often than not have some scar tissue of the lungs and airways, leading to a higher rate of respiratory illness.

Type

Magical

Origin

Magical

Cycle

Chronic, Acquired & Congenital

Rarity

Unique