Place the sausage in a saucepan and fill with water to cover. Bring to a boil and cook for 3 to 4 minutes. Drain and set aside.
In a large pot over medium-high heat, heat the oil. Add the onion, celery, and green pepper and cook until softened (but not browned), about 5 minutes, stirring occasionally. Add the chicken broth, tomatoes, okra, and reserved sausage, cover, and bring to a boil. Continue cooking, covered, over high heat for 5 minutes.
In a small bowl, whisk together the flour and 1/2 cup of water. Stir the flour mixture, salt, spices, and Worcestershire sauce into the pot, cover, and cook over high heat for another 10 minutes.
Add the scallions, shrimp, and crabmeat, reduce heat to medium, and cook for 5 minutes. Remove the bay leaf, stir in the parsley, and remove from heat. Cover and let sit for 5 minutes. Serve over rice.