The intestinal parasite Giardia lamblia changes outfits nearly as often as a fashion model on a Parisian runway. With more than 200 protein coats in its molecular wardrobe, this troublesome creature -- the cause of innumerable cases of diarrheal infections each year -- can change its appearance from one instant to the next, throwing the body's immune cells off track. Now, researchers report that Giardia parasites engineered to express all their surface proteins can work as vaccines that could help prevent or mitigate future infections.