Additional testing often includes the following (1): Stool ova and parasite testing Other tests to detect organ damage or for specific causes based on clinical findings In general, if a drug or allergic cause is not suspected based on clinical findings, 3 stool specimens should be examined for ova and parasites; however, negative findings do not rule out a parasitic cause (eg, trichinosis requires a muscle biopsy; toxocariasis and filarial infections require other tissue biopsies; duodenal aspirates may be needed to exclude specific parasites, such as Strongyloides).