What is a thesis statement about the theme of jealousy in Othello?

As it was in the ancient biblical story of Cain, the "worm of jealousy" moves into Othello's heart and causes him to commit his heinous act of killing Desdemona. Iago is the one who places this worm into Othello.
With the idea of the worm of jealousy, then, the student can write a persuasive essay designed to convince readers that Othello's jealousy is like a worm that burrows its way until it has destroyed the organ(s) it has attacked. 
Thus, there will be a need to write a thesis containing a blueprint of the three main points. This thesis will develop how this "worm" of jealousy makes its way through the heart of Othello and torments him to the point of suspicion and, later, madness. This thesis can state that the "worm" of jealousy is planted into Othello's mind by ideas suggested by others, and by two other situations or conditions such as false appearances (i.e. the handkerchief).
Here are some points to consider in formulating the thesis statement:
The seeds of jealousy are planted early in Act I even before Iago's worm has started to grow. When Brabantio accuses Othello of seducing Desdemona by witchcraft, he is defeated by Othello's testimony before the senate. Afterwards, Brabantio tells Othello:

Look to her, Moor, if thou hast eyes to see:She has deceived her father, and may thee (Act I, Scene 3, lines 288-289).

In Act II, Iago schemes to have Cassio drawn into a fight. Because of the disturbance, Iago strips Cassio of his rank, blaming him for the mayhem. Then, Iago moves in and convinces Cassio to beseech Desdemona to convince her husband to reinstate him as an officer.
Iago then goes to Othello and insinuates that Cassio and Desdemona are possibly lovers, making Othello suspicious. At the end of Act II, Iago tells Roderigo his plan:

Myself the while to draw the Moor apartAnd bring him jump when he may Cassio findSoliciting his wife, Aye, that's the way.Dull not device by coldness and delay (Act II, Scene 3, lines 348-351).

In Act III, Iago sees Cassio speaking with Desdemona as he pleads with her to ask Othello to reinstate him. Later, however, Iago tells Othello that he has seen Cassio "steal away so guilty-like" (Act III, Scene 3, line 40). Iago's insinuations heighten Othello's jealousy.
Othello demands “ocular proof” (Act III, Scene 3, line 365) of his wife's unfaithfulness, so Iago tells Othello he has seen Cassio “wipe his beard with” (Act III, Scene 3, line 439) the handkerchief Othello gave his wife. Hearing this, Othello vows to take vengeance on his wife and Cassio.
Iago's next act of treachery is to get his wife Emilia to give him the handkerchief Desdemona dropped. He later plants this handkerchief in Cassio's lodgings; then, he suggests that Othello listen as Iago questions Cassio. While he talks to Cassio, Iago tricks the former officer into speaking of his affair with a courtesan named Bianca. Iago whispers Bianca's name so softly that Othello cannot hear, causing Othello to assume the conversation is about Desdemona. Later, Bianca finds a duplicate handkerchief and accuses Cassio of giving her a second-hand gift; consequently, Othello believes Cassio originally received the handkerchief from Desdemona.
Finally, Othello makes Iago his lieutenant and asks Iago to accompany him and furnish him "with some swift means of death/ For the fair devil" (Act III, Scene 4, lines 479-480).
Enraged, Othello confronts Desdemona and strangles her to death.