Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 11 4 2016 12 25 499 506 Kareem HATAM-NAHAVANDI Department of Parasitology and Mycology, School of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran AND Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Infectious Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran Mehdi MOHEBALI Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Center for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran Amir-Hossein MAHVI Department of Environmental Health Engineering, School of Public Health, Tehran, Iran AND Center for Water Quality Research, Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran Hossein KESHAVARZ Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Center for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran Hamid-Reza NAJAFIAN Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Hamed MIRJALALI Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Gastroenterology and Liver Disease Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sasan REZAEI Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mostafa REZAEIAN Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Center for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran 2016 12 25 2016 12 25 Background: As a waterborne pathogen, Cryptosporidium is one of the most common causes of gastroenteritis in human and hoofed livestock animals. This study aimed to investigate the distribution of Cryptosporidium spp. in human and livestock wastewaters in Iran, by the 18S rRNA sequence analysis. Methods: A total of 54 raw wastewater samples collected from three urban treatment plants and two slaughterhouses during 2014-2015 in Tehran, Iran. The presence of the Cryptosporidium oocysts was assessed by immunofluorescence with monoclonal antibodies. To characterize the oocysts at the molecular level, the 18S rRNA gene of Cryptosporidium was PCR amplified and sequenced. Results: Of the 54 wastewater samples examined, 34 (62.9%) were positive for Cryptosporidium oocysts using the IFA. Of these, 70.5% (24/34) were positive by PCR, that 91.6% (22/24) were successfully sequenced. The species of C. andersoni (95.4%) and C. xiaoi (4.6%) were detected in livestock wastewater samples. Conclusion: C. andersoni was the major Cryptosporidium sp. found in the aquatic environmental wastewater samples. The high rate of detection of C. andersoni in domestic wastewater was probably the result of the predominancy of this species in cattle herds in Iran. The current study is the first report of C. xiaoi in Iran. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/1349 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/1349/627