It's not showing up on my avatar anymore D:

Update: Wait a minute. I went to my wardrobe and it's apparently there. Are finished infections being automatically removed now?

I had this same thing happen. Started the event with the Vaguely Sticky vial strain which matured some time in the wee hours of day. Tried to bite someone when I logged on only to discover I wasn't infected anymore. It matured while I was sleeping so I certainly didn't remove it.