In a large pot, add olive oil and heat over medium heat. Add celery, carrots, leeks, mushrooms, and sauté for about 10 minutes.
Add garlic, and stir for about one minute.
Add the remaining ingredients except for the Italian sausage.
Bring to a boil, then turn down to medium low, cover and allow to simmer for 30-45 minutes, or until the vegetables are soft and the wild rice is cooked.
Remove from heat, and add the browned Italian Sausage.
And, for a creamer soup, you can add the 1/2 cup heavy cream.
Top with grated parmesano reggiano cheese and serve.