Once you are bitten by Virginya Feng, you become a vampire. To cure you and her, the game tells you to visit Mamba Loa. If you're reading this, don't visit her. You need a mechanical skill of four points, two garlic gloves, and two packs of plasma. Then find a workbench, and make yourself two vampire cures. Then go to the Nighthowl Saloon and give Virginya Feng the cure. She'll gulp it down, and now she is no longer a vampire. Then you switch to the vampire cure in your "perk box" in the lower right-hand corner of the screen. Then when the cure is equipped, press the cirle button. Then you're Sim will drink it and you'll no longer be a vampire. But, even if you drink the potion, you'll still have the vampire bite as one of you're perks.