Claire's Infection= Raised by Another by My Friend

As soon as last night's episode ended, it hit me why Claire needed to raised Aaron. Richard Malkin told Claire she was the only one who could raise Aaron, so we were led to believe that something bad would happen with Aaron if she didn't, but the reality of it is that something bad would happen to Claire if she didn't have her son in her life. Aaron gone from her life seems to be the driving force behind her infection. I think when Malkin saw the blurry vision, he could sense Claire being infected, and the only way to keep Claire from getting infected is for her to keep her baby!

In Season 4, there's been speculation that Claire died, or nearly died in barracks when one of the houses exploded. By this time the pylons for Dharma were shut off, so MIB was able to enter the area and start manipulating. Later on Miles is staring at Claire with an odd look on his face, he gives this same look when he tries to read Sayid's "dead" body too. Upon his waking, he's infected, much like Claire already was. Later that night MIB comes to her in the form of Christian and manipulates her into leaving Aaron behind. Hopefully we'll see this happen.

I also think that Rousseau was infected as well, but she just didn't know it. She lost track of time, much like Claire, and her memory is a little fuzzy. Which could explain why Rousseau didn't recognize Jin and why she was by herself for so long.