. . . . . "The virus is spread by blood to blood contact and usually takes three to four hours for the symptoms and sulfur to manifest. However, Sam, who had blood contact with one of the infected people, showed none of the symptoms, even after five hours following his infection. When the doctor ran tests to check his blood, she found no traces of sulfur at all."@en . . . . . . . . . . . . "Croatoan Virus"@en . . "The virus is spread by blood to blood contact and usually takes three to four hours for the symptoms and sulfur to manifest. However, Sam, who had blood contact with one of the infected people, showed none of the symptoms, even after five hours following his infection. When the doctor ran tests to check his blood, she found no traces of sulfur at all. Near the end, it is revealed that the one responsible behind this virus is Duane Tanner, the man whom Sam saw Dean kill and who was in fact possessed. Communicating with the Yellow-Eyed Demon by the means of the Goblet of Blood, Duane informed the Yellow-Eyed Demon that \"The Winchester boy is immune, as expected.\""@en . "The Croatoan Virus, also dubbed \"Croatoan\", is a demonic disease in the Supernatural universe that infects people and turns them into murderous zombie-like creatures called \"Croats\" with varying degrees of intelligence, ranging from cruel and cunning to savage and mindless. It is transmitted through blood to blood contact. However Sam Winchester is shown to be immune to its effect. Lucifer, Azazel, and Pestilence hoped to use this virus to wreak havoc on Earth during the Apocalypse, but it was averted by Sam, Bobby, Dean and Castiel. Those with demon blood are immune to this supernatural illness of demonic origin."@en . . "Croatoan virus"@en . . . "The Croatoan Virus, also dubbed \"Croatoan\", is a demonic disease in the Supernatural universe that infects people and turns them into murderous zombie-like creatures called \"Croats\" with varying degrees of intelligence, ranging from cruel and cunning to savage and mindless. It is transmitted through blood to blood contact. However Sam Winchester is shown to be immune to its effect. Lucifer, Azazel, and Pestilence hoped to use this virus to wreak havoc on Earth during the Apocalypse, but it was averted by Sam, Bobby, Dean and Castiel. Those with demon blood are immune to this supernatural illness of demonic origin."@en . . . .