enterovesical fistula

sir,
i have had a symptom of pneumaturia since 3 months. At MS CT scan there is an adhesion between the bladder and the sigmoid colon. On cystography there are 2 fistulas with edema of the mucosa. on coloscopy no spesific was defined (chronic inflammation). Biosy post surgery revealed image of a debris of parasite in the fistula and image of malacoplakia. No manifestation of malignancy or tuberculosis.
In this case, what is the cause of this disease and what is the treatment.
Tkak you, sir