Disease

A disease was a detrimental medical condition that was not an injury.

Description
A disease could be transmitted in various ways: injury, ingestion, inhalation, mere contact, etc. Some were also caused by parasites. Creatures exposed to a disease ran the risk of becoming infected unless their immune system could fight it off. If the exposed individual lacked a strong enough constitution, the disease took hold. After an incubation period, the disease showed its symptoms, which persisted until the host was cured of the disease or died of it.

Contagious diseases spread readily in heavily or densely populated cities throughout Toril as well as along heavily trafficked trade routes. Both ordinary disease as well as parasitic infections were generally more common in hotter and wetter climates and in filthy or crowded conditions. When new or unknown diseases arose, most often this happened in rural or frontier settlements where the people encountered previously unknown afflictions while interacting with remote insects, beasts, and plants.

There was a generally important distinction between diseases which were "natural" and those which were "supernatural" or otherwise magical in origin. Natural diseases were acquired by mundane means, so even the most exotic of them could be treated (although perhaps not cured) with traditional or nonmagical care. Meanwhile, supernatural diseases were generally incurable with natural or normal medical efforts. Such magical diseases were often spread by magical creatures, such as lycanthropes or mummies.

Diseases in Society
Most people in Faerûn had no real medical knowledge and therefore relied first and foremost on experience when dealing with diseases, re-using methods that had helped themselves or close associates in the past, and second on the counsel of elders and the like. That said, most people had at least some shared understanding about how certain diseases were transmitted, and a baseline agreement about the general importance of cleanliness, rest, care, and the use of purgatives to treat illness. Beyond this, however, there were many disagreements about treatment methods, which was the case for at least two main reasons: first, there was the aforementioned reliance on personal experience&mdash;which could differ between individuals or groups&mdash;and second, there was false information that was intentionally spread. While some falsehoods were spread by evil factions with the goal of causing strife, such as by followers of Talona, other times they were spread by otherwise benevolent factions or churches in an effort to exert influence or to secure more coin for healing services.

The most well-known diseases in Faerûn included the so-called Five Fevers and Three Plagues.

Plagues
On Toril, widespread plagues were mostly a problem of the past by the 14 century DR. The reason for this was that diseases turned into widespread plagues when a population had never encountered them before. Toril had a long history of interracial intermingling and even crossbreeding. People were exposed to various diseases since childhood and therefore developed immunities and, being the descendants of survivors of plagues, they also inherited immunities from their ancestors. Overall, widespread plagues were not a problem in urban areas but more in isolated rural areas.

Another reason why plagues were contained was that preventive treatment was done on an official level by the priesthood and/or rulers. This was done either through official enforcement or by secretly mixing medical substances into food and water. People who were strangers and obviously afflicted were generally killed, at least in frontier regions. On the Sea of Fallen Stars, it was a widespread understanding that a ship carrying plague would signal this to other vessels by smearing blood or red paint on the sails. In response, other vessels would provide clerical healing if available, otherwise they were advised to burn the plague ship to the waterline with fire arrows or spells.

Common Diseases
The most common or well-known diseases in Faerûn were:

Other notable diseases included:

Regional Diseases
Regional diseases included:

Unique Diseases
Notable unique diseases included:

Non-Humanoid Diseases
Diseases affecting creatures other than humanoids included: