Ink Grave

Given that the cause is unknown, the conditions for transmission are also unknown. Some infections are seemingly random, whilst others are directly linked to contact with infected.

Unknown

There is no known treatment.

Ichor eye discharge and fatigue often starts out of nowhere within a week, and are followed closely by a complete lack of strength accompanied with fainting. 
After the initial onset, ichor will seep from the nose also and black veins will begin to form on the patient’s skin. Around this time abdominal pain is experienced as the internal organs begin to be consumed by the ichor within the body and delirium sets in.
Throughout the course of the disease, fluctuating temperatures can be experienced. The experience of temperature fluctuation generally tends to worsen the condition.
After a few more days painful, ichorous sores develop on the skin, accompanied by the vomiting of both blood and ichor. These symptoms are the last and the most painful and the infected is rarely lucid at this point.
After the onset of the final symptoms, death is ensured within a two days at maximum.

Once symptoms present they can be worsened by activity and movement but the infected is often to weak to even attempt such.

Given that the cause is unknown, there is known way to prevent infection other than avoiding contact with the infected.