Black Blood

The only known way of contracting the disease is through wounds inflicted directly from an infected being, usually from bites or scratch wounds. Touching an infected is not contagious.

There are four observable stages to the disease. The rate at which each stage develops varies greatly from person to person, but is generally related to the infected constitution, and the severity of the initial infection.

Stage One
The area around the wound starts to darken. The blood doesn't fully clot and becomes slightly darker. Some people experience mild to moderate nausea but may be related to contracting the wound, rather than the disease.

Stage Two
Fever starts to set in, accompanied by trembling and nausea. The area around the initial wounds continues to darken, and the blood around the wound is dark red. Their eyes also begin to darken. Most infected are still conscious and aware but finds it hard to concentrate on complex tasks.

Stage Three
At stage three, the infected is no longer able to take care of themselves. The fever is intense, and those few that remains conscious, suffer from extreme nausea, and will begin to vomit. The vomit will be bloodied and dark. Those that are still conscious will feel like they are dying and react accordingly.
Stage three always ends with the infected losing consciousness.

Stage Four
An infected in stage four is generally referred to as a 'blacker'.
The infected blood has turned black, as well as their eyes. The infected will regain consciousness and quickly regain their motor skills and will start attacking any living being near it, and attempt to eat them.
Additionally the infected will have very high pain tolerance and are able to ignore even the most severe wounds.
Although their behavior is very similar to that of a zombie, blackers appear to be capable of varying degrees of rational thought and even basic cooperation between themselves.
Scholars that adhere to the theory of Kazul being the origin of the disease, have speculated that the blackers ability to cooperate, may be what allowed him to control them, during The First Conflict of the gods.

No one has been able to find a cure for Black Blood, although many have tried. Especially followers of The Light have spent considerable resources on finding a cure, to no avail.
In Sylvania the Ministry of Magic has also dedicated considerable resources to understanding and curing the disease, but no magical cure has been found either. Some believe that Colibri, the goddess of healing and nature was able to cure the disease during The First Conflict of the gods before she ascended to godhood. The only way to stop the disease from progressing is by killing the infected. If an infected is killed before progressing to stage four, the progression of the disease stops immediately.

Since the only way to stop the disease is to kill the infected, the outcome of being infected is always fatal. Although infected in stage four aren't technically dead, most societies consider a stage four infected to be dead, as nothing remains of the original person.
There have been stories about infected that managed to hold on to parts of their past life, but none of them have been proven, and are likely false.

Most living beings are believed to be susceptible to the disease, including most animals. Only insects seem to be immune, or at least not visibly susceptible to the disease.

Any infected being, regardless of the stage of infection, is considered carriers and can infect anyone by scratching or biting them.

The only way to avoid being infected is to not be wounded by a blacker. If fighting one, it is a good idea to wear armor, and not have exposed skin, as even the slightest scratch can cause an infection.

Black Blood is a very rare disease, and in countries like Erekiath and Sylvania, no cases of the disease have been seen since The Second Conflict of the Gods, and even then the cases were rare. Adventures and travelers occasionally tell tales about encountering Blackers, in remote locations, but they are rarely able to prove these claims.