From Lost Fables Wiki
A natural bacteria found within all Ae which helps their gills to function at peak efficiency.
Non-infectious, caused by the subject not using their gills to filter saltwater for more than a week.
All Ae carry the bacteria.
After about a week of an Ae Il’ha not using their gills to filter saltwater specifically, the bacteria which normally is degraded and partially removed by this will begin to grow out of control. The result of this is an itchy, dry throat, and a persistent cough. The longer an Ae stays away from saltwater, the worse these symptoms will get, until the bacteria spreads into the lungs, at which case it spirals downward into pneumonia, usually after a full month of leaving the sickness untreated. At this point, the Ae will usually begin to suffer longer-lasting lung damage, and if, by the end of the following month, the Ae has not dealt with the sickness, this lung damage will become permanent, while the gills themselves will also begin to exude a thin pus and suffer long-term damage. The Ae usually does not survive the following month, but if they do, their lungs will essentially permanently cease all functions, while their gills’ ability to filter water begins to be seriously impaired, even in the long-term. If left untreated, the disease is fatal after five months.
Though the treatment is extremely simple, the consequences for avoiding it are dire indeed.
Simply breathing saltwater for extended periods of time, about a tenth of the time that one has gone without breathing it, will cure the disease entirely, normalizing the bacteria content in the gills.