Poison and sickness in Othello

Iago is described as being sick in several instances in this play. He makes reference to his own sickness when he says that the thought of Othello does "gnaw at his innards" like a poison. Later, his wife describes whomever must be planting jealous thoughts in Othello's mind as "a scurvy fellow." While this comment may seem innocuous at first glance, it is repeated later when Roderigo calls Iago's plan scurvy. The OED provides two definitions for scurvy. It can either refer to a bad man or to a skin disease. This shows that the sickness of jealousy begins in Iago who later infects Othello. Do you think this initial sickness gives Iago any excuse?