Identification of Cryptosporidium oocyst and Giardia cyst in of the samples of raw surface water of Kan River in Tehran

Abstract

Background: Giardia and Cryptosporidium are considered the most important causal agents of non-bloody diarrhea, especially among primary school children, in many countries, including Iran. Many rivers are contaminated with Cryptosporidium oocyst and Giardia lamblia cysts due to domestic wastewater or farm wastewater and also the living of rodents on their margins. The present study aims to evaluate Kan River contamination with Cryptosporidium oocyst and Giardia cyst in Tehran by molecular method. Materials and Methods: Sampling was conducted from different parts of the Kan River in different seasons in 2019. Firstly, the smear has been prepared from sediments after filtering the water and collecting the sediment, stained with trichrome and acid-fast methods, and finally examined microscopically. Then, they were amplified with the Nested-PCR method by using the specific primers: the giardian gene from Giardia and the 18s rRNA gene from Cryptosporidium. Positive samples were sequenced, and a phylogenetic tree was drawn. Results: 12 suspected samples of Giardia cyst and 2 suspected samples of Cryptosporidium oocyst were detected, but only 4 samples infected with Giardia lamblia were molecularly found, and no Cryptosporidium infection was observed. In terms of genotype, the identified Giardia was 100% consistent with human isolates of genotype B. Conclusion: The presence of Giardia lamblia cysts in the water of the Kan River indicates the contamination of this river by human-contaminating parasites.