Preheat oven to 350. Prepare a 9 "x 5" loaf pan with cooking; set aside. In a strainer set over a bowl, combine zucchini and salt and let stand, stirring once or twice, for 30 minutes. With your hands squeeze as much liquid out of the zucchini as possible. In a mixing bowl, combine onions, bell peppers, zucchini, egg whites, half cup ketchup, worcestershire sauce, mustard, garlic, black pepper, and oregano. Add chicken and bread crumbs. Mix well. Transfer chicken mixture to prepared pan, packing firmly into a loaf. Smooth top with the back of a spoon. Spread remaining ketchup evenly over top. Bake loaf for one hour, or until loaf reaches 185 on a meat thermometer. Let meat loaf rest on a rack for 10 minutes before slicing.