Dar-Kosis
-(noun; lit. 'holy disease'): an incurable wasting disease, also known as the 'Sacred Affliction' , so named because it is regarded as being holy to the Priest-Kings and those who are afflicted are considered as consecrated to the Priest-Kings. The disease is highly contagious, and those who suffer from it are required to wear yellow robes, and constantly sound a wooden clacker to warn of their approach.
Book 1: Tarnsman of Gor, pages 113 and 150-151

Dar-Kosis Pit
-(noun): a place where those afflicted with Dar-Kosis may voluntarily incarcerate themselves while they die. These huge pits have rudimentary shelter and a well. Once within, the sufferer may never leave. Food and necessities are thrown down from tarnback to help the diseased
Book 1: Tarnsman of Gor, page 151

QUOTES 

Suddenly to my horror, I saw the quarry of the larl.  It was a human being, moving with surprising alacrity over the rough ground. To my astonishment, I saw it wore the yellow cerements of the sufferer of Dar-Kosis, that virulent, incurable, wasting disease of Gor.
-Tarnsman of Gor p149

He was now bent and crooked, like a broken blasted shrub in his yellow shroudlike robe. The hood concealed his face. Pointing to its shadowed concealed face it whispered "The Holy Disease." That was the literal translation of Dar-Kosis 'the Holy Disease' or equivalent the Sacred Affliction. The disease is named that because it is regarded as being holy to the Priest Kings, and those who suffer from it are regarded as consecrated to the Priest Kings. Accordingly it is regarded as heresy to shed their blood. On the other hand, the Afflicted, as they are called, have little to fear from their fellow men. Their disease is so highly contagious, so invariably devastating in its effects, and so feared on the planet that even the boldest of outlaws gives them a wide berth. Accordingly, the afflicted enjoy a large amount of freedom of movement on Gor. They are of course, warned to stay away from the habitations of men, and if they approach too closely, they are sometimes stoned. Oddly enough, casuisically, stoning the Afflicted is not regarded as a violation of the Priest Kings supposed injunction against shedding their blood. As an act of charity, Initiates have arranged at various places Dar-Kosis pits where the Afflicted may volutarily imprison themselves to be fed with food hurled downward from the backs of passing tarns. Once in a Dar-Kosis pit the Afflicted are not allowed to depart. I was glad that it was night and that the hood of the man was drawn, for I had no desire to look on what pieces of flesh might still cling to his skull.
-Tarnsman of Gor pp150,151

"No," said Flaminius smiling. "No," he took another swallow. "I thought to find," he said, "an immunization against Dar-Kosis."
"Dar-Kosis is incurable," I said. 
"At one time," he said, "centuries ago men of my Caste claimed age was incurable. Others did not accept this and continued to work. The result was the Stablization Serums. Dar-Kosis or the Holy Disease or Sacred Affliction is a virulent wasting disease of Gor. Those afflicted with it commonly spoken of simply as the afflicted ones may not enter into normal society They wander the country side in shroudlike yellow rags beating a wooden clapping device to warn men from their path; some of them volunteer to be placed in Dar-Kosis pits several of which are in the vicintiy of Ar, where they are fed and given drink, and are of course isolated; the disease is extremely contagious. those who contract the disease are regarded by law as dead." 
-Assassin of Gor pp265,266

Flaminius speaking to Tarl Cabot of his research on Dar-Kosis and the development of a vaccine that showed promise

"I had," he said. " Shortly before the fire we developed a strain of urts resistant to the Dar-Kosis organism; a serum cultured from their blood was injected in other animals, which subsequently we were unable to infect.  It was tentative, only a beginning, but I had hoped, I had hoped very much."
-Assassin of Gor p267.

Research on Dar-Kosis and the violent opposition of the Initiates

"I (Flaminius) and others worked secretly in the Cylinder of Physicians. We devoted our time, those ahn in the day in which we could work to study, research and experiment. Unfortunately for spite and for gold word of our work was brought to the High Initiate, by a minor Physician discharged from our staff for incompetence. The Cylinder of Initiates demanded that the High Council of the Caste of Physicians put an end to our work, not only that it be discontinued but that our results to that date be destroyed. The Physicians, I am pleased to say stood with us. There is little love lost between Physicians and Initiates. Before the next passage hand, he said, armed men broke into the Cylinder of Physicians; the floors we worked on were burned; the Cylinder itself was seriously damaged; our work our records, the animals we used were all destroyed; several of my staff were slain, others driven away." 
-Assassin of Gor p267.

Flaminius speaking of the preclinical stage of Dar Kosis

"At the games on the second of En Kara in the Stadium of blades," said he, "I saw the High Initiate Complicius Serenus."
"So?," I said.
"He does not know it," said Flaminius, "nor will he for perhaps a year learn."
"What?," I asked.
"That he is dying of Dar-Kosis, he said" 
-Assassin of Gor pp268,269.
Note: Dar-Kosis can be diagnosed at a distance by sight.

Kuruus and Flaminius speaking of Dar-Kosis

"Dar-Kosis" I said, "is regarded as an instrument of Priest Kings, used to smite those who displease them."
"Another myth of Initiates," said Flaminius unpleasantly.
"But how do you know that?", I queried.
"I do not care," said Flaminius, "if it is true or not. I am a Physician."
-Assassin of Gor p266.