Filth fever

Filth fever was a sickness characterized by fever, slowness of movement, and physical weakness. It was spread by bites from contaminated animals, and could be deadly if left untreated.

Acquisition
The disease was most commonly contracted from the bites of creatures like rats, dire rats, otyughs,  trolls, and wererats. It could also be acquired if an injury became infected due to exposure to a filthy environment, such as a sewer or a battlefield.

Filth fever was also inflicted by injuries from a diseased weapon. It was one of several diseases that could be inflicted using the contagion spell.

Effects
Those suffering from filth fever experienced a raging fever that impacted their whole body, sometimes accompanied alternatingly with freezing chills. The disease caused a steady degradation of both reflexes, mobility, and stamina, and made it difficult for the infected individual to complete tasks that involved physical strength or exertion&mdash;including swinging a weapon &mdash;as well as interfered with the body's natural healing. In extreme cases, sufferers would simply waste away, and could become so weak that they died.

With luck, a healthy immune system could fight off the disease in a matter of days.

History
In the mid-to-late 14 century DR, filth fever was among the diseases that one could potentially contract from trudging through the sewage of the sewers beneath Mulmaster and Waterdeep. It could also be encountered in the Underdark.

By the, magic weapons that could inflict filth fever were favored among Talontar blightlords as well as some of the more cruel Red Wizards of Thay.

During the Shadovar–Thay War, the Charnel Fields of Surcross became so choked with corpses and rot that the area became a hotbed for a unique strain of filth fever.

In the late 15 century DR, the Dead Rats&mdash;a gang of wererats active in Luskan and Neverwinter&mdash;were known to be carriers of filth fever.

As of the, a magically animated puppet of Halaster Blackcloak was purportedly researching a cure for filth fever in the Arcane Chambers of Undermountain, but was in fact just randomly mixing harmless substances.