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Molecular Evaluation of Conventional Microscopic Method Versus Fecal Antigen Capture Enzyme-Linked Immunosorbent Assay and Rapid Immunochromatographic Assay for Diagnosis of Cryptosporidium Infection

Mohamed, Amr Mohamed Abdelfattah*†; Ahmed, Mona Abdelfattah‡§; Zaglool, Dina Abdullah║¶; Ahmed, Sabah Abd-El-Ghany†‡

Infectious Diseases in Clinical Practice: January 2015 - Volume 23 - Issue 1 - p 26–31
doi: 10.1097/IPC.0000000000000169
Original Articles
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Background Cryptosporidium has emerged as an important cause of diarrheal illness worldwide, especially among young children and patients with immune deficiencies.

Aim The present study aimed to investigate the frequency of Cryptosporidium infection among suspected versus nonsuspected patients and to evaluate the performances of conventional microscopic assay, Cryptosporidium antigen detection enzyme-linked immunosorbent assay (CAD-ELISA), Crypto-Antigen Rapid Test (CA-RT), for diagnosis of Cryptosporidium infection using Cryptosporidium-specific polymerase chain reaction (CS-PCR) as criterion standard test.

Methods A total of 181 diarrheic stool samples including 105 from suspected patients and 76 from nonsuspected ones were collected.

Results The results revealed higher rate of infection among suspected patients (25% among diarrheic children, 24.2% among elderly/immune suppressed patients) as compared with nonsuspected patients (6.6% among immune-competent apparently healthy adults). Furthermore, conventional microscopic assay exhibited higher sensitivity (83.3%) as compared with CAD-ELISA (75%) and CA-RT (45.8%). On the other hand, higher specificity was shown for CA-RT (99.4%) and CAD-ELISA (98.7%) as compared with conventional assay (92.9%). Meanwhile, CA-RT and CAD-ELISA showed higher positive predictive values (91.7%, 90%) and lower negative predictive values (92.3%, 96.9%) than conventional assay (64.5%, 97.3%).

Conclusions No single test is perfect for diagnosis of cryptosporidiosis, and it is worth mentioning that a significant percentage of Cryptosporidium infections would have been missed if any of these assays had been the sole method of diagnosis. It is suggested to include an antigen detection immunoassay, preferably ELISA, in addition to microscopy for better diagnosis of Cryptosporidium infection.

From the *Clinical Laboratory Diagnosis, Department of Animal Medicine, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt; †Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia; ‡Parasitology Department, Faculty of Medicine, Ain-Shams University, Cairo, Egypt; §Laboratory Consultant of Medical Parasitology, King Abdullah Medical City, Makkah, Saudi Arabia; ║Parasitology Department, Faculty of Medicine, Assuit University, Assuit, Egypt; and ¶Laboratory Consultant of Medical Parasitology, Al-Noor Specialist Hospital.

Correspondence to: Amr Mohamed Abdelfattah Mohamed, Clinical Laboratory Diagnosis, Department of Animal Medicine, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt. E-mail: amrmohamed2004@yahoo.com.

The authors have no funding or conflicts of interest to disclose.

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