What is the role of fenbendazole trial in the stepwise approach to chronic diarrhea?

• A. Diagnostic imaging technique
• B. Treatment trial after fecal analysis to rule out parasitic infection
• C. Genetic test
• D. Nutritional supplement

Answer: (B)

In chronic diarrhea, after initial stool testing, giving a short trial of anthelmintic therapy serves as a diagnostic step to uncover hidden parasitic infection. Fenbendazole acts broadly against intestinal worms, and a clinical improvement during or after the trial suggests parasites were contributing to the symptoms even if stool tests were negative. This happens because tests can miss parasites due to intermittent shedding or low parasite burden, so a positive treatment response helps confirm occult parasitism and guides management. It’s not a diagnostic imaging technique, not a genetic test, and not a nutritional supplement, which is why this option best fits the idea of using a therapeutic trial to rule out parasitic infection. If there’s no improvement, other causes are pursued.