Cyclosporiasis is caused by which organism?

• A. Cyclospora cayetanensis
• B. Giardia lamblia
• C. Ascaris lumbricoides
• D. Plasmodium falciparum

Answer: (A)

Recognizing the causative agent of cyclosporiasis. The illness is caused by Cyclospora cayetanensis, a coccidian parasite transmitted when people ingest sporulated oocysts in contaminated food or water. Infections typically produce watery diarrhea, stomach cramps, and may relapse after initial improvement. Diagnosis often relies on stool examination to find the characteristic oocysts, which are about 8–10 micrometers in diameter and show variable acid-fast staining. Outbreaks have been linked to imported fresh produce, such as berries and leafy greens, highlighting its foodborne nature. Treatment commonly includes trimethoprim-sulfamethoxazole. By contrast, Giardia lamblia causes giardiasis with greasy, foul-smelling stools; Ascaris lumbricoides is a large intestinal worm that can cause obstruction and malnutrition; Plasmodium falciparum leads to malaria with cyclical fevers and anemia.