Which organism causes cyclosporiasis?

• A. Cyclospora cayetanensis
• B. Giardia lamblia
• C. Entamoeba histolytica
• D. Cryptosporidium parvum

Answer: (A)

Cyclosporiasis is an intestinal infection caused by Cyclospora cayetanensis, a coccidian parasite. This organism is the one associated with cyclosporiasis, helping to distinguish it from the other diarrheal pathogens listed. Infections typically produce prolonged watery diarrhea with cramps and sometimes weight loss, often starting about a week after consuming contaminated food or water. Diagnosis relies on stool examination to identify the parasite’s oocysts, which are relatively large for a protozoan (about 8–10 micrometers) and can be variably acid-fast and autofluorescent under UV light. Treatment usually involves trimethoprim-sulfamethoxazole. In contrast, Giardia lamblia causes giardiasis, Entamoeba histolytica causes amoebic dysentery, and Cryptosporidium parvum causes cryptosporidiosis, each with its own distinct clinical features and diagnostic clues.