Evaluation of immunomagnetic separation and the sucrose flotation methods coupled with immunofluorescence or PCR for detection of Cryptosporidium and Giardia (oo)cysts in water samples

Introduction: Detection of Cryptosporidium and Giardia parasites in water samples is usually performed by US Environmental Protection Agency 1623 method. Nevertheless, the USEPA1623 method still need improvement, to prevent and control the water borne parasitic disease. Therefore, we undertook the present study. Materials and methods: Totally 48 surface water samples were collected. Four samples from 12 sites and samples of each site were evaluated by IMS-IFA, SF-IFA, IMS-PCR and SF-PCR. These typically involve sample filtration by membrane filter, separation by Sucrose flotation or immunomagnetic separation (IMS) methods and detection of (oo)cysts by PCR or immunofluorescent staining. Results: Same samples were evaluated by the different techniques at the same time showing a rate of Cryptosporidium oocysts detection of 8 (66.6%) by IMS-IFA, 7 (58.3%) by SF-IFA, 10 (83%) by IMS-PCR and 0% by SF-PCR.Giardia cysts detected in, 5 (41.7%) by IMS-IFA, 3(25%) by SF-IFA, 7 (58.4%) by IMS-PCR and 2 (17%) by SF-PCR. Conclusion: Data analysis showed a higher sensitivity of IMS-PCR for the detection of Giardia and Cryptosporidium (oo)cysts respectively in comparison with others techniques used in this study. IMS prior to DNA extraction showed a higher sensitivity to eliminate or reduce PCR inhibitors that presence in water samples.